[oweals/busybox.git] / miscutils / bc.c

/* vi: set sw=4 ts=4: */
/*
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 * Copyright (c) 2018 Gavin D. Howard and contributors.
 */
//config:config BC
//config:       bool "bc (45 kb; 49 kb when combined with dc)"
//config:       default y
//config:       help
//config:       bc is a command-line, arbitrary-precision calculator with a
//config:       Turing-complete language. See the GNU bc manual
//config:       (https://www.gnu.org/software/bc/manual/bc.html) and bc spec
//config:       (http://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html).
//config:
//config:       This bc has five differences to the GNU bc:
//config:         1) The period (.) is a shortcut for "last", as in the BSD bc.
//config:         2) Arrays are copied before being passed as arguments to
//config:            functions. This behavior is required by the bc spec.
//config:         3) Arrays can be passed to the builtin "length" function to get
//config:            the number of elements in the array. This prints "1":
//config:               a[0] = 0; length(a[])
//config:         4) The precedence of the boolean "not" operator (!) is equal to
//config:            that of the unary minus (-) negation operator. This still
//config:            allows POSIX-compliant scripts to work while somewhat
//config:            preserving expected behavior (versus C) and making parsing
//config:            easier.
//config:         5) "read()" accepts expressions, not only numeric literals.
//config:
//config:       Options:
//config:         -i  --interactive  force interactive mode
//config:         -q  --quiet        don't print version and copyright
//config:         -s  --standard     error if any non-POSIX extensions are used
//config:         -w  --warn         warn if any non-POSIX extensions are used
//config:         -l  --mathlib      use predefined math routines:
//config:               s(expr) sine in radians
//config:               c(expr) cosine in radians
//config:               a(expr) arctangent, returning radians
//config:               l(expr) natural log
//config:               e(expr) raises e to the power of expr
//config:               j(n, x) Bessel function of integer order n of x
//config:
//config:config DC
//config:       bool "dc (38 kb; 49 kb when combined with bc)"
//config:       default y
//config:       help
//config:       dc is a reverse-polish notation command-line calculator which
//config:       supports unlimited precision arithmetic. See the FreeBSD man page
//config:       (https://www.unix.com/man-page/FreeBSD/1/dc/) and GNU dc manual
//config:       (https://www.gnu.org/software/bc/manual/dc-1.05/html_mono/dc.html).
//config:
//config:       This dc has a few differences from the two above:
//config:         1) When printing a byte stream (command "P"), this dc follows what
//config:            the FreeBSD dc does.
//config:         2) Implements the GNU extensions for divmod ("~") and
//config:            modular exponentiation ("|").
//config:         3) Implements all FreeBSD extensions, except for "J" and "M".
//config:         4) Like the FreeBSD dc, this dc supports extended registers.
//config:            However, they are implemented differently. When it encounters
//config:            whitespace where a register should be, it skips the whitespace.
//config:            If the character following is not a lowercase letter, an error
//config:            is issued. Otherwise, the register name is parsed by the
//config:            following regex:
//config:               [a-z][a-z0-9_]*
//config:            This generally means that register names will be surrounded by
//config:            whitespace. Examples:
//config:               l idx s temp L index S temp2 < do_thing
//config:            Also note that, like the FreeBSD dc, extended registers are not
//config:            allowed unless the "-x" option is given.
//config:
//config:config FEATURE_DC_SMALL
//config:       bool "Minimal dc implementation (4.2 kb), not using bc code base"
//config:       depends on DC && !BC
//config:       default n
//config:
//config:config FEATURE_DC_LIBM
//config:       bool "Enable power and exp functions (requires libm)"
//config:       default y
//config:       depends on FEATURE_DC_SMALL
//config:       help
//config:       Enable power and exp functions.
//config:       NOTE: This will require libm to be present for linking.
//config:
//config:config FEATURE_BC_SIGNALS
//config:       bool "Interactive mode (+4kb)"
//config:       default y
//config:       depends on (BC || DC) && !FEATURE_DC_SMALL
//config:       help
//config:       Enable interactive mode: when started on a tty,
//config:       ^C interrupts execution and returns to command line,
//config:       errors also return to command line instead of exiting,
//config:       line editing with history is available.
//config:
//config:       With this option off, input can still be taken from tty,
//config:       but all errors are fatal, ^C is fatal,
//config:       tty is treated exactly the same as any other
//config:       standard input (IOW: no line editing).
//config:
//config:config FEATURE_BC_LONG_OPTIONS
//config:       bool "Enable bc/dc long options"
//config:       default y
//config:       depends on (BC || DC) && !FEATURE_DC_SMALL
//config:       help
//config:       Enable long options for bc and dc.

//applet:IF_BC(APPLET(bc, BB_DIR_USR_BIN, BB_SUID_DROP))
//applet:IF_DC(APPLET(dc, BB_DIR_USR_BIN, BB_SUID_DROP))

//kbuild:lib-$(CONFIG_BC) += bc.o
//kbuild:lib-$(CONFIG_DC) += bc.o

//See www.gnu.org/software/bc/manual/bc.html
//usage:#define bc_trivial_usage
//usage:       "[-sqliw] FILE..."
//usage:
//usage:#define bc_full_usage "\n"
//usage:     "\nArbitrary precision calculator"
//usage:     "\n"
///////:     "\n        -i      Interactive" - has no effect for now
//usage:     "\n        -q      Quiet"
//usage:     "\n        -l      Load standard math library"
//usage:     "\n        -s      Be POSIX compatible"
//usage:     "\n        -w      Warn if extensions are used"
///////:     "\n        -v      Version"
//usage:     "\n"
//usage:     "\n$BC_LINE_LENGTH changes output width"
//usage:
//usage:#define bc_example_usage
//usage:       "3 + 4.129\n"
//usage:       "1903 - 2893\n"
//usage:       "-129 * 213.28935\n"
//usage:       "12 / -1932\n"
//usage:       "12 % 12\n"
//usage:       "34 ^ 189\n"
//usage:       "scale = 13\n"
//usage:       "ibase = 2\n"
//usage:       "obase = A\n"
//usage:
//usage:#define dc_trivial_usage
//usage:       IF_NOT_FEATURE_DC_SMALL("[-x] ")"[-eSCRIPT]... [-fFILE]... [FILE]..."
//usage:
//usage:#define dc_full_usage "\n"
//usage:     "\nTiny RPN calculator. Operations:"
//usage:     "\n+, -, *, /, %, ~, ^," IF_NOT_FEATURE_DC_SMALL(" |,")
//usage:     "\np - print top of the stack (without popping)"
//usage:     "\nf - print entire stack"
//usage:     "\nk - pop the value and set the precision"
//usage:     "\ni - pop the value and set input radix"
//usage:     "\no - pop the value and set output radix"
//usage:     "\nExamples: dc -e'2 2 + p' -> 4, dc -e'8 8 * 2 2 + / p' -> 16"
//usage:
//usage:#define dc_example_usage
//usage:       "$ dc -e'2 2 + p'\n"
//usage:       "4\n"
//usage:       "$ dc -e'8 8 \\* 2 2 + / p'\n"
//usage:       "16\n"
//usage:       "$ dc -e'0 1 & p'\n"
//usage:       "0\n"
//usage:       "$ dc -e'0 1 | p'\n"
//usage:       "1\n"
//usage:       "$ echo '72 9 / 8 * p' | dc\n"
//usage:       "64\n"

#include "libbb.h"
#include "common_bufsiz.h"

#if ENABLE_FEATURE_DC_SMALL
# include "dc.c"
#else

typedef enum BcStatus {
        BC_STATUS_SUCCESS = 0,
        BC_STATUS_FAILURE = 1,
        BC_STATUS_PARSE_EMPTY_EXP = 2, // bc_parse_expr_empty_ok() uses this
} BcStatus;

#define BC_VEC_INVALID_IDX ((size_t) -1)
#define BC_VEC_START_CAP (1 << 5)

typedef void (*BcVecFree)(void *) FAST_FUNC;

typedef struct BcVec {
        char *v;
        size_t len;
        size_t cap;
        size_t size;
        BcVecFree dtor;
} BcVec;

typedef signed char BcDig;

typedef struct BcNum {
        BcDig *restrict num;
        size_t rdx;
        size_t len;
        size_t cap;
        bool neg;
} BcNum;

#define BC_NUM_MIN_BASE         ((unsigned long) 2)
#define BC_NUM_MAX_IBASE        ((unsigned long) 16)
// larger value might speed up BIGNUM calculations a bit:
#define BC_NUM_DEF_SIZE         (16)
#define BC_NUM_PRINT_WIDTH      (69)

#define BC_NUM_KARATSUBA_LEN    (32)

typedef enum BcInst {

#if ENABLE_BC
        BC_INST_INC_PRE,
        BC_INST_DEC_PRE,
        BC_INST_INC_POST,
        BC_INST_DEC_POST,
#endif

        BC_INST_NEG,

        BC_INST_POWER,
        BC_INST_MULTIPLY,
        BC_INST_DIVIDE,
        BC_INST_MODULUS,
        BC_INST_PLUS,
        BC_INST_MINUS,

        BC_INST_REL_EQ,
        BC_INST_REL_LE,
        BC_INST_REL_GE,
        BC_INST_REL_NE,
        BC_INST_REL_LT,
        BC_INST_REL_GT,

        BC_INST_BOOL_NOT,
        BC_INST_BOOL_OR,
        BC_INST_BOOL_AND,

#if ENABLE_BC
        BC_INST_ASSIGN_POWER,
        BC_INST_ASSIGN_MULTIPLY,
        BC_INST_ASSIGN_DIVIDE,
        BC_INST_ASSIGN_MODULUS,
        BC_INST_ASSIGN_PLUS,
        BC_INST_ASSIGN_MINUS,
#endif
        BC_INST_ASSIGN,

        BC_INST_NUM,
        BC_INST_VAR,
        BC_INST_ARRAY_ELEM,
        BC_INST_ARRAY,

        BC_INST_SCALE_FUNC,
        BC_INST_IBASE,
        BC_INST_SCALE,
        BC_INST_LAST,
        BC_INST_LENGTH,
        BC_INST_READ,
        BC_INST_OBASE,
        BC_INST_SQRT,

        BC_INST_PRINT,
        BC_INST_PRINT_POP,
        BC_INST_STR,
        BC_INST_PRINT_STR,

#if ENABLE_BC
        BC_INST_JUMP,
        BC_INST_JUMP_ZERO,

        BC_INST_CALL,

        BC_INST_RET,
        BC_INST_RET0,

        BC_INST_HALT,
#endif

        BC_INST_POP,
        BC_INST_POP_EXEC,

#if ENABLE_DC
        BC_INST_MODEXP,
        BC_INST_DIVMOD,

        BC_INST_EXECUTE,
        BC_INST_EXEC_COND,

        BC_INST_ASCIIFY,
        BC_INST_PRINT_STREAM,

        BC_INST_PRINT_STACK,
        BC_INST_CLEAR_STACK,
        BC_INST_STACK_LEN,
        BC_INST_DUPLICATE,
        BC_INST_SWAP,

        BC_INST_LOAD,
        BC_INST_PUSH_VAR,
        BC_INST_PUSH_TO_VAR,

        BC_INST_QUIT,
        BC_INST_NQUIT,

        BC_INST_INVALID = -1,
#endif

} BcInst;

typedef struct BcId {
        char *name;
        size_t idx;
} BcId;

typedef struct BcFunc {
        BcVec code;
        BcVec labels;
        size_t nparams;
        BcVec autos;
} BcFunc;

typedef enum BcResultType {

        BC_RESULT_TEMP,

        BC_RESULT_VAR,
        BC_RESULT_ARRAY_ELEM,
        BC_RESULT_ARRAY,

        BC_RESULT_STR,

        BC_RESULT_IBASE,
        BC_RESULT_SCALE,
        BC_RESULT_LAST,

        // These are between to calculate ibase, obase, and last from instructions.
        BC_RESULT_CONSTANT,
        BC_RESULT_ONE,

        BC_RESULT_OBASE,

} BcResultType;

typedef union BcResultData {
        BcNum n;
        BcVec v;
        BcId id;
} BcResultData;

typedef struct BcResult {
        BcResultType t;
        BcResultData d;
} BcResult;

typedef struct BcInstPtr {
        size_t func;
        size_t idx;
        size_t len;
} BcInstPtr;

// BC_LEX_NEG is not used in lexing; it is only for parsing.
typedef enum BcLexType {

        BC_LEX_EOF,
        BC_LEX_INVALID,

        BC_LEX_OP_INC,
        BC_LEX_OP_DEC,

        BC_LEX_NEG,

        BC_LEX_OP_POWER,
        BC_LEX_OP_MULTIPLY,
        BC_LEX_OP_DIVIDE,
        BC_LEX_OP_MODULUS,
        BC_LEX_OP_PLUS,
        BC_LEX_OP_MINUS,

        BC_LEX_OP_REL_EQ,
        BC_LEX_OP_REL_LE,
        BC_LEX_OP_REL_GE,
        BC_LEX_OP_REL_NE,
        BC_LEX_OP_REL_LT,
        BC_LEX_OP_REL_GT,

        BC_LEX_OP_BOOL_NOT,
        BC_LEX_OP_BOOL_OR,
        BC_LEX_OP_BOOL_AND,

        BC_LEX_OP_ASSIGN_POWER,
        BC_LEX_OP_ASSIGN_MULTIPLY,
        BC_LEX_OP_ASSIGN_DIVIDE,
        BC_LEX_OP_ASSIGN_MODULUS,
        BC_LEX_OP_ASSIGN_PLUS,
        BC_LEX_OP_ASSIGN_MINUS,
        BC_LEX_OP_ASSIGN,

        BC_LEX_NLINE,
        BC_LEX_WHITESPACE,

        BC_LEX_LPAREN,
        BC_LEX_RPAREN,

        BC_LEX_LBRACKET,
        BC_LEX_COMMA,
        BC_LEX_RBRACKET,

        BC_LEX_LBRACE,
        BC_LEX_SCOLON,
        BC_LEX_RBRACE,

        BC_LEX_STR,
        BC_LEX_NAME,
        BC_LEX_NUMBER,

        BC_LEX_KEY_1st_keyword,
        BC_LEX_KEY_AUTO = BC_LEX_KEY_1st_keyword,
        BC_LEX_KEY_BREAK,
        BC_LEX_KEY_CONTINUE,
        BC_LEX_KEY_DEFINE,
        BC_LEX_KEY_ELSE,
        BC_LEX_KEY_FOR,
        BC_LEX_KEY_HALT,
        // code uses "type - BC_LEX_KEY_IBASE + BC_INST_IBASE" construct,
        BC_LEX_KEY_IBASE,  // relative order should match for: BC_INST_IBASE
        BC_LEX_KEY_IF,
        BC_LEX_KEY_LAST,   // relative order should match for: BC_INST_LAST
        BC_LEX_KEY_LENGTH,
        BC_LEX_KEY_LIMITS,
        BC_LEX_KEY_OBASE,  // relative order should match for: BC_INST_OBASE
        BC_LEX_KEY_PRINT,
        BC_LEX_KEY_QUIT,
        BC_LEX_KEY_READ,
        BC_LEX_KEY_RETURN,
        BC_LEX_KEY_SCALE,
        BC_LEX_KEY_SQRT,
        BC_LEX_KEY_WHILE,

#if ENABLE_DC
        BC_LEX_EQ_NO_REG,
        BC_LEX_OP_MODEXP,
        BC_LEX_OP_DIVMOD,

        BC_LEX_COLON,
        BC_LEX_ELSE,
        BC_LEX_EXECUTE,
        BC_LEX_PRINT_STACK,
        BC_LEX_CLEAR_STACK,
        BC_LEX_STACK_LEVEL,
        BC_LEX_DUPLICATE,
        BC_LEX_SWAP,
        BC_LEX_POP,

        BC_LEX_ASCIIFY,
        BC_LEX_PRINT_STREAM,

        BC_LEX_STORE_IBASE,
        BC_LEX_STORE_SCALE,
        BC_LEX_LOAD,
        BC_LEX_LOAD_POP,
        BC_LEX_STORE_PUSH,
        BC_LEX_STORE_OBASE,
        BC_LEX_PRINT_POP,
        BC_LEX_NQUIT,
        BC_LEX_SCALE_FACTOR,
#endif
} BcLexType;
// must match order of BC_LEX_KEY_foo etc above
#if ENABLE_BC
struct BcLexKeyword {
        char name8[8];
};
#define BC_LEX_KW_ENTRY(a, b) \
        { .name8 = a /*, .posix = b */ }
static const struct BcLexKeyword bc_lex_kws[20] = {
        BC_LEX_KW_ENTRY("auto"    , 1), // 0
        BC_LEX_KW_ENTRY("break"   , 1), // 1
        BC_LEX_KW_ENTRY("continue", 0), // 2 note: this one has no terminating NUL
        BC_LEX_KW_ENTRY("define"  , 1), // 3

        BC_LEX_KW_ENTRY("else"    , 0), // 4
        BC_LEX_KW_ENTRY("for"     , 1), // 5
        BC_LEX_KW_ENTRY("halt"    , 0), // 6
        BC_LEX_KW_ENTRY("ibase"   , 1), // 7

        BC_LEX_KW_ENTRY("if"      , 1), // 8
        BC_LEX_KW_ENTRY("last"    , 0), // 9
        BC_LEX_KW_ENTRY("length"  , 1), // 10
        BC_LEX_KW_ENTRY("limits"  , 0), // 11

        BC_LEX_KW_ENTRY("obase"   , 1), // 12
        BC_LEX_KW_ENTRY("print"   , 0), // 13
        BC_LEX_KW_ENTRY("quit"    , 1), // 14
        BC_LEX_KW_ENTRY("read"    , 0), // 15

        BC_LEX_KW_ENTRY("return"  , 1), // 16
        BC_LEX_KW_ENTRY("scale"   , 1), // 17
        BC_LEX_KW_ENTRY("sqrt"    , 1), // 18
        BC_LEX_KW_ENTRY("while"   , 1), // 19
};
#undef BC_LEX_KW_ENTRY
enum {
        POSIX_KWORD_MASK = 0
                | (1 << 0)
                | (1 << 1)
                | (0 << 2)
                | (1 << 3)
                \
                | (0 << 4)
                | (1 << 5)
                | (0 << 6)
                | (1 << 7)
                \
                | (1 << 8)
                | (0 << 9)
                | (1 << 10)
                | (0 << 11)
                \
                | (1 << 12)
                | (0 << 13)
                | (1 << 14)
                | (0 << 15)
                \
                | (1 << 16)
                | (1 << 17)
                | (1 << 18)
                | (1 << 19)
};
#define bc_lex_kws_POSIX(i) ((1 << (i)) & POSIX_KWORD_MASK)
#endif

#if ENABLE_FEATURE_BC_SIGNALS || ENABLE_FEATURE_CLEAN_UP
# define BC_STATUS BcStatus
#else
# define BC_STATUS void
#endif

typedef struct BcLex {

        const char *buf;
        size_t i;
        size_t line;
        size_t len;
        bool newline;

        struct {
                BcLexType t;
                BcLexType last;
                BcVec v;
        } t;

} BcLex;

#define BC_PARSE_STREND ((char) UCHAR_MAX)

#define BC_PARSE_REL    (1 << 0)
#define BC_PARSE_PRINT  (1 << 1)
#define BC_PARSE_NOCALL (1 << 2)
#define BC_PARSE_NOREAD (1 << 3)
#define BC_PARSE_ARRAY  (1 << 4)

#define BC_PARSE_TOP_FLAG_PTR(parse) ((uint8_t *) bc_vec_top(&(parse)->flags))
#define BC_PARSE_TOP_FLAG(parse) (*(BC_PARSE_TOP_FLAG_PTR(parse)))

#define BC_PARSE_FLAG_FUNC_INNER (1 << 0)
#define BC_PARSE_FUNC_INNER(parse) \
        (BC_PARSE_TOP_FLAG(parse) & BC_PARSE_FLAG_FUNC_INNER)

#define BC_PARSE_FLAG_FUNC (1 << 1)
#define BC_PARSE_FUNC(parse) (BC_PARSE_TOP_FLAG(parse) & BC_PARSE_FLAG_FUNC)

#define BC_PARSE_FLAG_BODY (1 << 2)
#define BC_PARSE_BODY(parse) (BC_PARSE_TOP_FLAG(parse) & BC_PARSE_FLAG_BODY)

#define BC_PARSE_FLAG_LOOP (1 << 3)
#define BC_PARSE_LOOP(parse) (BC_PARSE_TOP_FLAG(parse) & BC_PARSE_FLAG_LOOP)

#define BC_PARSE_FLAG_LOOP_INNER (1 << 4)
#define BC_PARSE_LOOP_INNER(parse) \
        (BC_PARSE_TOP_FLAG(parse) & BC_PARSE_FLAG_LOOP_INNER)

#define BC_PARSE_FLAG_IF (1 << 5)
#define BC_PARSE_IF(parse) (BC_PARSE_TOP_FLAG(parse) & BC_PARSE_FLAG_IF)

#define BC_PARSE_FLAG_ELSE (1 << 6)
#define BC_PARSE_ELSE(parse) (BC_PARSE_TOP_FLAG(parse) & BC_PARSE_FLAG_ELSE)

#define BC_PARSE_FLAG_IF_END (1 << 7)
#define BC_PARSE_IF_END(parse) (BC_PARSE_TOP_FLAG(parse) & BC_PARSE_FLAG_IF_END)

#define BC_PARSE_CAN_EXEC(parse)                                             \
        (!(BC_PARSE_TOP_FLAG(parse) &                                            \
           (BC_PARSE_FLAG_FUNC_INNER | BC_PARSE_FLAG_FUNC | BC_PARSE_FLAG_BODY | \
            BC_PARSE_FLAG_LOOP | BC_PARSE_FLAG_LOOP_INNER | BC_PARSE_FLAG_IF |   \
            BC_PARSE_FLAG_ELSE | BC_PARSE_FLAG_IF_END)))

struct BcParse;

struct BcProgram;

typedef struct BcParse {

        BcLex l;

        BcVec flags;

        BcVec exits;
        BcVec conds;

        BcVec ops;

        BcFunc *func;
        size_t fidx;

        size_t nbraces;
        bool auto_part;

} BcParse;

typedef struct BcProgram {

        size_t len;
        size_t scale;

        BcNum ib;
        size_t ib_t;
        BcNum ob;
        size_t ob_t;

        BcNum hexb;

#if ENABLE_DC
        BcNum strmb;
#endif

        BcVec results;
        BcVec stack;

        BcVec fns;
        BcVec fn_map;

        BcVec vars;
        BcVec var_map;

        BcVec arrs;
        BcVec arr_map;

        BcVec strs;
        BcVec consts;

        const char *file;

        BcNum last;
        BcNum zero;
        BcNum one;

        size_t nchars;

} BcProgram;

#define BC_PROG_STACK(s, n) ((s)->len >= ((size_t) n))

#define BC_PROG_MAIN (0)
#define BC_PROG_READ (1)
#if ENABLE_DC
#define BC_PROG_REQ_FUNCS (2)
#endif

#define BC_PROG_STR(n) (!(n)->num && !(n)->cap)
#define BC_PROG_NUM(r, n) \
        ((r)->t != BC_RESULT_ARRAY && (r)->t != BC_RESULT_STR && !BC_PROG_STR(n))

#define BC_FLAG_W (1 << 0)
#define BC_FLAG_V (1 << 1)
#define BC_FLAG_S (1 << 2)
#define BC_FLAG_Q (1 << 3)
#define BC_FLAG_L (1 << 4)
#define BC_FLAG_I (1 << 5)
#define DC_FLAG_X (1 << 6)

#define BC_MAX(a, b) ((a) > (b) ? (a) : (b))
#define BC_MIN(a, b) ((a) < (b) ? (a) : (b))

#define BC_MAX_OBASE    ((unsigned) 999)
#define BC_MAX_DIM      ((unsigned) INT_MAX)
#define BC_MAX_SCALE    ((unsigned) UINT_MAX)
#define BC_MAX_STRING   ((unsigned) UINT_MAX - 1)
#define BC_MAX_NUM      BC_MAX_STRING
// Unused apart from "limits" message. Just show a "biggish number" there.
//#define BC_MAX_NAME     BC_MAX_STRING
//#define BC_MAX_EXP      ((unsigned long) LONG_MAX)
//#define BC_MAX_VARS     ((unsigned long) SIZE_MAX - 1)
#define BC_MAX_NAME_STR "999999999"
#define BC_MAX_EXP_STR  "999999999"
#define BC_MAX_VARS_STR "999999999"

#define BC_MAX_OBASE_STR "999"

#if INT_MAX == 2147483647
# define BC_MAX_DIM_STR "2147483647"
#elif INT_MAX == 9223372036854775807
# define BC_MAX_DIM_STR "9223372036854775807"
#else
# error Strange INT_MAX
#endif

#if UINT_MAX == 4294967295
# define BC_MAX_SCALE_STR  "4294967295"
# define BC_MAX_STRING_STR "4294967294"
#elif UINT_MAX == 18446744073709551615
# define BC_MAX_SCALE_STR  "18446744073709551615"
# define BC_MAX_STRING_STR "18446744073709551614"
#else
# error Strange UINT_MAX
#endif
#define BC_MAX_NUM_STR BC_MAX_STRING_STR

struct globals {
        IF_FEATURE_BC_SIGNALS(smallint ttyin;)
        IF_FEATURE_CLEAN_UP(smallint exiting;)
        smallint in_read;
        char sbgn;
        char send;

        BcParse prs;
        BcProgram prog;

        // For error messages. Can be set to current parsed line,
        // or [TODO] to current executing line (can be before last parsed one)
        unsigned err_line;

        BcVec files;

        char *env_args;

#if ENABLE_FEATURE_EDITING
        line_input_t *line_input_state;
#endif
} FIX_ALIASING;
#define G (*ptr_to_globals)
#define INIT_G() do { \
        SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \
} while (0)
#define FREE_G() do { \
        FREE_PTR_TO_GLOBALS(); \
} while (0)
#define G_posix (ENABLE_BC && (option_mask32 & BC_FLAG_S))
#define G_warn  (ENABLE_BC && (option_mask32 & BC_FLAG_W))
#define G_exreg (ENABLE_DC && (option_mask32 & DC_FLAG_X))
#if ENABLE_FEATURE_BC_SIGNALS
# define G_interrupt bb_got_signal
# define G_ttyin     G.ttyin
#else
# define G_interrupt 0
# define G_ttyin     0
#endif
#if ENABLE_FEATURE_CLEAN_UP
# define G_exiting G.exiting
#else
# define G_exiting 0
#endif
#define IS_BC (ENABLE_BC && (!ENABLE_DC || applet_name[0] == 'b'))
#define IS_DC (ENABLE_DC && (!ENABLE_BC || applet_name[0] != 'b'))

#if ENABLE_BC

// This is a bit array that corresponds to token types. An entry is
// true if the token is valid in an expression, false otherwise.
enum {
        BC_PARSE_EXPRS_BITS = 0
        + ((uint64_t)((0 << 0)+(0 << 1)+(1 << 2)+(1 << 3)+(1 << 4)+(1 << 5)+(1 << 6)+(1 << 7)) << (0*8))
        + ((uint64_t)((1 << 0)+(1 << 1)+(1 << 2)+(1 << 3)+(1 << 4)+(1 << 5)+(1 << 6)+(1 << 7)) << (1*8))
        + ((uint64_t)((1 << 0)+(1 << 1)+(1 << 2)+(1 << 3)+(1 << 4)+(1 << 5)+(1 << 6)+(1 << 7)) << (2*8))
        + ((uint64_t)((1 << 0)+(1 << 1)+(1 << 2)+(0 << 3)+(0 << 4)+(1 << 5)+(1 << 6)+(0 << 7)) << (3*8))
        + ((uint64_t)((0 << 0)+(0 << 1)+(0 << 2)+(0 << 3)+(0 << 4)+(0 << 5)+(1 << 6)+(1 << 7)) << (4*8))
        + ((uint64_t)((0 << 0)+(0 << 1)+(0 << 2)+(0 << 3)+(0 << 4)+(0 << 5)+(0 << 6)+(1 << 7)) << (5*8))
        + ((uint64_t)((0 << 0)+(1 << 1)+(1 << 2)+(1 << 3)+(1 << 4)+(0 << 5)+(0 << 6)+(1 << 7)) << (6*8))
        + ((uint64_t)((0 << 0)+(1 << 1)+(1 << 2)+(0 << 3)                                    ) << (7*8))
};
static ALWAYS_INLINE long bc_parse_exprs(unsigned i)
{
#if ULONG_MAX > 0xffffffff
        // 64-bit version (will not work correctly for 32-bit longs!)
        return BC_PARSE_EXPRS_BITS & (1UL << i);
#else
        // 32-bit version
        unsigned long m = (uint32_t)BC_PARSE_EXPRS_BITS;
        if (i >= 32) {
                m = (uint32_t)(BC_PARSE_EXPRS_BITS >> 32);
                i &= 31;
        }
        return m & (1UL << i);
#endif
}

// This is an array of data for operators that correspond to token types.
static const uint8_t bc_parse_ops[] = {
#define OP(p,l) ((int)(l) * 0x10 + (p))
        OP(0, false), OP( 0, false ), // inc dec
        OP(1, false), // neg
        OP(2, false),
        OP(3, true ), OP( 3, true  ), OP( 3, true  ), // pow mul div
        OP(4, true ), OP( 4, true  ), // mod + -
        OP(6, true ), OP( 6, true  ), OP( 6, true  ), OP( 6, true  ), OP( 6, true  ), OP( 6, true ), // == <= >= != < >
        OP(1, false), // not
        OP(7, true ), OP( 7, true  ), // or and
        OP(5, false), OP( 5, false ), OP( 5, false ), OP( 5, false ), OP( 5, false ), // ^= *= /= %= +=
        OP(5, false), OP( 5, false ), // -= =
#undef OP
};
#define bc_parse_op_PREC(i) (bc_parse_ops[i] & 0x0f)
#define bc_parse_op_LEFT(i) (bc_parse_ops[i] & 0x10)

// Byte array of up to 4 BC_LEX's, packed into 32-bit word
typedef uint32_t BcParseNext;

// These identify what tokens can come after expressions in certain cases.
enum {
#define BC_PARSE_NEXT4(a,b,c,d) ( (a) | ((b)<<8) | ((c)<<16) | ((((d)|0x80)<<24)) )
#define BC_PARSE_NEXT2(a,b)     BC_PARSE_NEXT4(a,b,0xff,0xff)
#define BC_PARSE_NEXT1(a)       BC_PARSE_NEXT4(a,0xff,0xff,0xff)
        bc_parse_next_expr  = BC_PARSE_NEXT4(BC_LEX_NLINE,  BC_LEX_SCOLON, BC_LEX_RBRACE, BC_LEX_EOF),
        bc_parse_next_param = BC_PARSE_NEXT2(BC_LEX_RPAREN, BC_LEX_COMMA),
        bc_parse_next_print = BC_PARSE_NEXT4(BC_LEX_COMMA,  BC_LEX_NLINE,  BC_LEX_SCOLON, BC_LEX_EOF),
        bc_parse_next_rel   = BC_PARSE_NEXT1(BC_LEX_RPAREN),
        bc_parse_next_elem  = BC_PARSE_NEXT1(BC_LEX_RBRACKET),
        bc_parse_next_for   = BC_PARSE_NEXT1(BC_LEX_SCOLON),
        bc_parse_next_read  = BC_PARSE_NEXT2(BC_LEX_NLINE,  BC_LEX_EOF),
#undef BC_PARSE_NEXT4
#undef BC_PARSE_NEXT2
#undef BC_PARSE_NEXT1
};
#endif // ENABLE_BC

#if ENABLE_DC
static const //BcLexType - should be this type, but narrower type saves size:
uint8_t
dc_lex_regs[] = {
        BC_LEX_OP_REL_EQ, BC_LEX_OP_REL_LE, BC_LEX_OP_REL_GE, BC_LEX_OP_REL_NE,
        BC_LEX_OP_REL_LT, BC_LEX_OP_REL_GT, BC_LEX_SCOLON, BC_LEX_COLON,
        BC_LEX_ELSE, BC_LEX_LOAD, BC_LEX_LOAD_POP, BC_LEX_OP_ASSIGN,
        BC_LEX_STORE_PUSH,
};

static const //BcLexType - should be this type
uint8_t
dc_lex_tokens[] = {
        BC_LEX_OP_MODULUS, BC_LEX_INVALID, BC_LEX_INVALID, BC_LEX_LPAREN,
        BC_LEX_INVALID, BC_LEX_OP_MULTIPLY, BC_LEX_OP_PLUS, BC_LEX_INVALID,
        BC_LEX_OP_MINUS, BC_LEX_INVALID, BC_LEX_OP_DIVIDE,
        BC_LEX_INVALID, BC_LEX_INVALID, BC_LEX_INVALID, BC_LEX_INVALID,
        BC_LEX_INVALID, BC_LEX_INVALID, BC_LEX_INVALID, BC_LEX_INVALID,
        BC_LEX_INVALID, BC_LEX_INVALID,
        BC_LEX_COLON, BC_LEX_SCOLON, BC_LEX_OP_REL_GT, BC_LEX_OP_REL_EQ,
        BC_LEX_OP_REL_LT, BC_LEX_KEY_READ, BC_LEX_INVALID,
        BC_LEX_INVALID, BC_LEX_INVALID, BC_LEX_INVALID, BC_LEX_INVALID,
        BC_LEX_INVALID, BC_LEX_INVALID, BC_LEX_EQ_NO_REG, BC_LEX_INVALID,
        BC_LEX_KEY_IBASE, BC_LEX_INVALID, BC_LEX_KEY_SCALE, BC_LEX_LOAD_POP,
        BC_LEX_INVALID, BC_LEX_OP_BOOL_NOT, BC_LEX_KEY_OBASE, BC_LEX_PRINT_STREAM,
        BC_LEX_NQUIT, BC_LEX_POP, BC_LEX_STORE_PUSH, BC_LEX_INVALID, BC_LEX_INVALID,
        BC_LEX_INVALID, BC_LEX_INVALID, BC_LEX_SCALE_FACTOR, BC_LEX_INVALID,
        BC_LEX_KEY_LENGTH, BC_LEX_INVALID, BC_LEX_INVALID, BC_LEX_INVALID,
        BC_LEX_OP_POWER, BC_LEX_NEG, BC_LEX_INVALID,
        BC_LEX_ASCIIFY, BC_LEX_INVALID, BC_LEX_CLEAR_STACK, BC_LEX_DUPLICATE,
        BC_LEX_ELSE, BC_LEX_PRINT_STACK, BC_LEX_INVALID, BC_LEX_INVALID,
        BC_LEX_STORE_IBASE, BC_LEX_INVALID, BC_LEX_STORE_SCALE, BC_LEX_LOAD,
        BC_LEX_INVALID, BC_LEX_PRINT_POP, BC_LEX_STORE_OBASE, BC_LEX_KEY_PRINT,
        BC_LEX_KEY_QUIT, BC_LEX_SWAP, BC_LEX_OP_ASSIGN, BC_LEX_INVALID,
        BC_LEX_INVALID, BC_LEX_KEY_SQRT, BC_LEX_INVALID, BC_LEX_EXECUTE,
        BC_LEX_INVALID, BC_LEX_STACK_LEVEL,
        BC_LEX_LBRACE, BC_LEX_OP_MODEXP, BC_LEX_INVALID, BC_LEX_OP_DIVMOD,
        BC_LEX_INVALID
};

static const //BcInst - should be this type. Using signed narrow type since BC_INST_INVALID is -1
int8_t
dc_parse_insts[] = {
        BC_INST_INVALID, BC_INST_INVALID, BC_INST_INVALID, BC_INST_REL_GE,
        BC_INST_INVALID, BC_INST_POWER, BC_INST_MULTIPLY, BC_INST_DIVIDE,
        BC_INST_MODULUS, BC_INST_PLUS, BC_INST_MINUS,
        BC_INST_INVALID, BC_INST_INVALID, BC_INST_INVALID, BC_INST_INVALID,
        BC_INST_INVALID, BC_INST_INVALID,
        BC_INST_BOOL_NOT, BC_INST_INVALID, BC_INST_INVALID,
        BC_INST_INVALID, BC_INST_INVALID, BC_INST_INVALID, BC_INST_INVALID,
        BC_INST_INVALID, BC_INST_INVALID, BC_INST_INVALID,
        BC_INST_INVALID, BC_INST_INVALID, BC_INST_REL_GT, BC_INST_INVALID,
        BC_INST_INVALID, BC_INST_INVALID, BC_INST_INVALID, BC_INST_REL_GE,
        BC_INST_INVALID, BC_INST_INVALID,
        BC_INST_INVALID, BC_INST_INVALID, BC_INST_INVALID,
        BC_INST_INVALID, BC_INST_INVALID, BC_INST_INVALID, BC_INST_INVALID,
        BC_INST_INVALID, BC_INST_INVALID, BC_INST_INVALID, BC_INST_IBASE,
        BC_INST_INVALID, BC_INST_INVALID, BC_INST_LENGTH, BC_INST_INVALID,
        BC_INST_OBASE, BC_INST_PRINT, BC_INST_QUIT, BC_INST_INVALID,
        BC_INST_INVALID, BC_INST_SCALE, BC_INST_SQRT, BC_INST_INVALID,
        BC_INST_REL_EQ, BC_INST_MODEXP, BC_INST_DIVMOD, BC_INST_INVALID,
        BC_INST_INVALID, BC_INST_EXECUTE, BC_INST_PRINT_STACK, BC_INST_CLEAR_STACK,
        BC_INST_STACK_LEN, BC_INST_DUPLICATE, BC_INST_SWAP, BC_INST_POP,
        BC_INST_ASCIIFY, BC_INST_PRINT_STREAM, BC_INST_INVALID, BC_INST_INVALID,
        BC_INST_INVALID, BC_INST_INVALID, BC_INST_INVALID, BC_INST_INVALID,
        BC_INST_PRINT, BC_INST_NQUIT, BC_INST_SCALE_FUNC,
};
#endif // ENABLE_DC

// In configurations where errors abort instead of propagating error
// return code up the call chain, functions returning BC_STATUS
// actually don't return anything, they always succeed and return "void".
// A macro wrapper is provided, which makes this statement work:
//  s = zbc_func(...)
// and makes it visible to the compiler that s is always zero,
// allowing compiler to optimize dead code after the statement.
//
// To make code more readable, each such function has a "z"
// ("always returning zero") prefix, i.e. zbc_foo or zdc_foo.
//
#if ENABLE_FEATURE_BC_SIGNALS || ENABLE_FEATURE_CLEAN_UP
# define ERRORS_ARE_FATAL 0
# define ERRORFUNC        /*nothing*/
# define ERROR_RETURN(a)  a
//moved up: # define BC_STATUS        BcStatus
# define RETURN_STATUS(v) return (v)
#else
# define ERRORS_ARE_FATAL 1
# define ERRORFUNC        NORETURN
# define ERROR_RETURN(a)  /*nothing*/
//moved up: # define BC_STATUS        void
# define RETURN_STATUS(v) do { ((void)(v)); return; } while (0)
#endif

#define BC_NUM_NEG(n, neg)      ((((ssize_t)(n)) ^ -((ssize_t)(neg))) + (neg))
#define BC_NUM_ONE(n)           ((n)->len == 1 && (n)->rdx == 0 && (n)->num[0] == 1)
#define BC_NUM_INT(n)           ((n)->len - (n)->rdx)
//#define BC_NUM_AREQ(a, b)       (BC_MAX((a)->rdx, (b)->rdx) + BC_MAX(BC_NUM_INT(a), BC_NUM_INT(b)) + 1)
static /*ALWAYS_INLINE*/ size_t BC_NUM_AREQ(BcNum *a, BcNum *b)
{
        return BC_MAX(a->rdx, b->rdx) + BC_MAX(BC_NUM_INT(a), BC_NUM_INT(b)) + 1;
}
//#define BC_NUM_MREQ(a, b, scale) (BC_NUM_INT(a) + BC_NUM_INT(b) + BC_MAX((scale), (a)->rdx + (b)->rdx) + 1)
static /*ALWAYS_INLINE*/ size_t BC_NUM_MREQ(BcNum *a, BcNum *b, size_t scale)
{
        return BC_NUM_INT(a) + BC_NUM_INT(b) + BC_MAX(scale, a->rdx + b->rdx) + 1;
}

typedef void (*BcNumDigitOp)(size_t, size_t, bool) FAST_FUNC;

typedef BC_STATUS (*BcNumBinaryOp)(BcNum *, BcNum *, BcNum *, size_t) FAST_FUNC;

static BC_STATUS zbc_num_binary(BcNum *a, BcNum *b, BcNum *c, size_t scale,
                        BcNumBinaryOp op, size_t req);
static FAST_FUNC BC_STATUS zbc_num_a(BcNum *a, BcNum *b, BcNum *restrict c, size_t scale);
static FAST_FUNC BC_STATUS zbc_num_s(BcNum *a, BcNum *b, BcNum *restrict c, size_t scale);
static FAST_FUNC BC_STATUS zbc_num_p(BcNum *a, BcNum *b, BcNum *restrict c, size_t scale);
static FAST_FUNC BC_STATUS zbc_num_m(BcNum *a, BcNum *b, BcNum *restrict c, size_t scale);
static FAST_FUNC BC_STATUS zbc_num_d(BcNum *a, BcNum *b, BcNum *restrict c, size_t scale);
static FAST_FUNC BC_STATUS zbc_num_rem(BcNum *a, BcNum *b, BcNum *restrict c, size_t scale);

static FAST_FUNC BC_STATUS zbc_num_add(BcNum *a, BcNum *b, BcNum *c, size_t scale)
{
        BcNumBinaryOp op = (!a->neg == !b->neg) ? zbc_num_a : zbc_num_s;
        (void) scale;
        RETURN_STATUS(zbc_num_binary(a, b, c, false, op, BC_NUM_AREQ(a, b)));
}

static FAST_FUNC BC_STATUS zbc_num_sub(BcNum *a, BcNum *b, BcNum *c, size_t scale)
{
        BcNumBinaryOp op = (!a->neg == !b->neg) ? zbc_num_s : zbc_num_a;
        (void) scale;
        RETURN_STATUS(zbc_num_binary(a, b, c, true, op, BC_NUM_AREQ(a, b)));
}

static FAST_FUNC BC_STATUS zbc_num_mul(BcNum *a, BcNum *b, BcNum *c, size_t scale)
{
        size_t req = BC_NUM_MREQ(a, b, scale);
        RETURN_STATUS(zbc_num_binary(a, b, c, scale, zbc_num_m, req));
}

static FAST_FUNC BC_STATUS zbc_num_div(BcNum *a, BcNum *b, BcNum *c, size_t scale)
{
        size_t req = BC_NUM_MREQ(a, b, scale);
        RETURN_STATUS(zbc_num_binary(a, b, c, scale, zbc_num_d, req));
}

static FAST_FUNC BC_STATUS zbc_num_mod(BcNum *a, BcNum *b, BcNum *c, size_t scale)
{
        size_t req = BC_NUM_MREQ(a, b, scale);
        RETURN_STATUS(zbc_num_binary(a, b, c, scale, zbc_num_rem, req));
}

static FAST_FUNC BC_STATUS zbc_num_pow(BcNum *a, BcNum *b, BcNum *c, size_t scale)
{
        RETURN_STATUS(zbc_num_binary(a, b, c, scale, zbc_num_p, a->len * b->len + 1));
}

static const BcNumBinaryOp zbc_program_ops[] = {
        zbc_num_pow, zbc_num_mul, zbc_num_div, zbc_num_mod, zbc_num_add, zbc_num_sub,
};
#if ERRORS_ARE_FATAL
# define zbc_num_add(...) (zbc_num_add(__VA_ARGS__), BC_STATUS_SUCCESS)
# define zbc_num_sub(...) (zbc_num_sub(__VA_ARGS__), BC_STATUS_SUCCESS)
# define zbc_num_mul(...) (zbc_num_mul(__VA_ARGS__), BC_STATUS_SUCCESS)
# define zbc_num_div(...) (zbc_num_div(__VA_ARGS__), BC_STATUS_SUCCESS)
# define zbc_num_mod(...) (zbc_num_mod(__VA_ARGS__), BC_STATUS_SUCCESS)
# define zbc_num_pow(...) (zbc_num_pow(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static void fflush_and_check(void)
{
        fflush_all();
        if (ferror(stdout) || ferror(stderr))
                bb_perror_msg_and_die("output error");
}

#if ENABLE_FEATURE_CLEAN_UP
#define QUIT_OR_RETURN_TO_MAIN \
do { \
        IF_FEATURE_BC_SIGNALS(G_ttyin = 0;) /* do not loop in main loop anymore */ \
        G_exiting = 1; \
        return BC_STATUS_FAILURE; \
} while (0)
#else
#define QUIT_OR_RETURN_TO_MAIN quit()
#endif

static void quit(void) NORETURN;
static void quit(void)
{
        if (ferror(stdin))
                bb_perror_msg_and_die("input error");
        fflush_and_check();
        exit(0);
}

static void bc_verror_msg(const char *fmt, va_list p)
{
        const char *sv = sv; /* for compiler */
        if (G.prog.file) {
                sv = applet_name;
                applet_name = xasprintf("%s: %s:%u", applet_name, G.prog.file, G.err_line);
        }
        bb_verror_msg(fmt, p, NULL);
        if (G.prog.file) {
                free((char*)applet_name);
                applet_name = sv;
        }
}

static NOINLINE ERRORFUNC int bc_error_fmt(const char *fmt, ...)
{
        va_list p;

        va_start(p, fmt);
        bc_verror_msg(fmt, p);
        va_end(p);

        if (!ENABLE_FEATURE_CLEAN_UP && !G_ttyin)
                exit(1);
        ERROR_RETURN(return BC_STATUS_FAILURE;)
}

#if ENABLE_BC
static NOINLINE int bc_posix_error_fmt(const char *fmt, ...)
{
        va_list p;

        // Are non-POSIX constructs totally ok?
        if (!(option_mask32 & (BC_FLAG_S|BC_FLAG_W)))
                return BC_STATUS_SUCCESS; // yes

        va_start(p, fmt);
        bc_verror_msg(fmt, p);
        va_end(p);

        // Do we treat non-POSIX constructs as errors?
        if (!(option_mask32 & BC_FLAG_S))
                return BC_STATUS_SUCCESS; // no, it's a warning
        if (!ENABLE_FEATURE_CLEAN_UP && !G_ttyin)
                exit(1);
        return BC_STATUS_FAILURE;
}
#endif

// We use error functions with "return bc_error(FMT[, PARAMS])" idiom.
// This idiom begs for tail-call optimization, but for it to work,
// function must not have caller-cleaned parameters on stack.
// Unfortunately, vararg function API does exactly that on most arches.
// Thus, use these shims for the cases when we have no vararg PARAMS:
static ERRORFUNC int bc_error(const char *msg)
{
        ERROR_RETURN(return) bc_error_fmt("%s", msg);
}
static ERRORFUNC int bc_error_bad_character(char c)
{
        ERROR_RETURN(return) bc_error_fmt("bad character '%c'", c);
}
static ERRORFUNC int bc_error_bad_expression(void)
{
        ERROR_RETURN(return) bc_error("bad expression");
}
static ERRORFUNC int bc_error_bad_token(void)
{
        ERROR_RETURN(return) bc_error("bad token");
}
static ERRORFUNC int bc_error_stack_has_too_few_elements(void)
{
        ERROR_RETURN(return) bc_error("stack has too few elements");
}
static ERRORFUNC int bc_error_variable_is_wrong_type(void)
{
        ERROR_RETURN(return) bc_error("variable is wrong type");
}
static ERRORFUNC int bc_error_nested_read_call(void)
{
        ERROR_RETURN(return) bc_error("read() call inside of a read() call");
}
#if ENABLE_BC
static int bc_POSIX_requires(const char *msg)
{
        return bc_posix_error_fmt("POSIX requires %s", msg);
}
static int bc_POSIX_does_not_allow(const char *msg)
{
        return bc_posix_error_fmt("%s%s", "POSIX does not allow ", msg);
}
static int bc_POSIX_does_not_allow_bool_ops_this_is_bad(const char *msg)
{
        return bc_posix_error_fmt("%s%s %s", "POSIX does not allow ", "boolean operators; the following is bad:", msg);
}
static int bc_POSIX_does_not_allow_empty_X_expression_in_for(const char *msg)
{
        return bc_posix_error_fmt("%san empty %s expression in a for loop", "POSIX does not allow ", msg);
}
#endif

static void bc_vec_grow(BcVec *v, size_t n)
{
        size_t cap = v->cap * 2;
        while (cap < v->len + n) cap *= 2;
        v->v = xrealloc(v->v, v->size * cap);
        v->cap = cap;
}

static void bc_vec_init(BcVec *v, size_t esize, BcVecFree dtor)
{
        v->size = esize;
        v->cap = BC_VEC_START_CAP;
        v->len = 0;
        v->dtor = dtor;
        v->v = xmalloc(esize * BC_VEC_START_CAP);
}

static void bc_char_vec_init(BcVec *v)
{
        bc_vec_init(v, sizeof(char), NULL);
}

static void bc_vec_expand(BcVec *v, size_t req)
{
        if (v->cap < req) {
                v->v = xrealloc(v->v, v->size * req);
                v->cap = req;
        }
}

static void bc_vec_pop(BcVec *v)
{
        v->len--;
        if (v->dtor)
                v->dtor(v->v + (v->size * v->len));
}

static void bc_vec_npop(BcVec *v, size_t n)
{
        if (!v->dtor)
                v->len -= n;
        else {
                size_t len = v->len - n;
                while (v->len > len) v->dtor(v->v + (v->size * --v->len));
        }
}

static void bc_vec_pop_all(BcVec *v)
{
        bc_vec_npop(v, v->len);
}

static void bc_vec_push(BcVec *v, const void *data)
{
        if (v->len + 1 > v->cap) bc_vec_grow(v, 1);
        memmove(v->v + (v->size * v->len), data, v->size);
        v->len += 1;
}

static void bc_vec_pushByte(BcVec *v, char data)
{
        bc_vec_push(v, &data);
}

static void bc_vec_pushZeroByte(BcVec *v)
{
        //bc_vec_pushByte(v, '\0');
        // better:
        bc_vec_push(v, &const_int_0);
}

static void bc_vec_pushAt(BcVec *v, const void *data, size_t idx)
{
        if (idx == v->len)
                bc_vec_push(v, data);
        else {

                char *ptr;

                if (v->len == v->cap) bc_vec_grow(v, 1);

                ptr = v->v + v->size * idx;

                memmove(ptr + v->size, ptr, v->size * (v->len++ - idx));
                memmove(ptr, data, v->size);
        }
}

static void bc_vec_string(BcVec *v, size_t len, const char *str)
{
        bc_vec_pop_all(v);
        bc_vec_expand(v, len + 1);
        memcpy(v->v, str, len);
        v->len = len;

        bc_vec_pushZeroByte(v);
}

static void bc_vec_concat(BcVec *v, const char *str)
{
        size_t len, slen;

        if (v->len == 0) bc_vec_pushZeroByte(v);

        slen = strlen(str);
        len = v->len + slen;

        if (v->cap < len) bc_vec_grow(v, slen);
        strcpy(v->v + v->len - 1, str);

        v->len = len;
}

static void *bc_vec_item(const BcVec *v, size_t idx)
{
        return v->v + v->size * idx;
}

static char** bc_program_str(size_t idx)
{
        return bc_vec_item(&G.prog.strs, idx);
}

static BcFunc* bc_program_func(size_t idx)
{
        return bc_vec_item(&G.prog.fns, idx);
}

static void *bc_vec_item_rev(const BcVec *v, size_t idx)
{
        return v->v + v->size * (v->len - idx - 1);
}

static void *bc_vec_top(const BcVec *v)
{
        return v->v + v->size * (v->len - 1);
}

static FAST_FUNC void bc_vec_free(void *vec)
{
        BcVec *v = (BcVec *) vec;
        bc_vec_pop_all(v);
        free(v->v);
}

static int bc_id_cmp(const void *e1, const void *e2)
{
        return strcmp(((const BcId *) e1)->name, ((const BcId *) e2)->name);
}

static FAST_FUNC void bc_id_free(void *id)
{
        free(((BcId *) id)->name);
}

static size_t bc_map_find(const BcVec *v, const void *ptr)
{
        size_t low = 0, high = v->len;

        while (low < high) {

                size_t mid = (low + high) / 2;
                BcId *id = bc_vec_item(v, mid);
                int result = bc_id_cmp(ptr, id);

                if (result == 0)
                        return mid;
                else if (result < 0)
                        high = mid;
                else
                        low = mid + 1;
        }

        return low;
}

static int bc_map_insert(BcVec *v, const void *ptr, size_t *i)
{
        size_t n = *i = bc_map_find(v, ptr);

        if (n == v->len)
                bc_vec_push(v, ptr);
        else if (!bc_id_cmp(ptr, bc_vec_item(v, n)))
                return 0; // "was not inserted"
        else
                bc_vec_pushAt(v, ptr, n);
        return 1; // "was inserted"
}

#if ENABLE_BC
static size_t bc_map_index(const BcVec *v, const void *ptr)
{
        size_t i = bc_map_find(v, ptr);
        if (i >= v->len) return BC_VEC_INVALID_IDX;
        return bc_id_cmp(ptr, bc_vec_item(v, i)) ? BC_VEC_INVALID_IDX : i;
}
#endif

static int push_input_byte(BcVec *vec, char c)
{
        if ((c < ' ' && c != '\t' && c != '\r' && c != '\n') // also allow '\v' '\f'?
         || c > 0x7e
        ) {
                // Bad chars on this line, ignore entire line
                bc_error_fmt("illegal character 0x%02x", c);
                return 1;
        }
        bc_vec_pushByte(vec, (char)c);
        return 0;
}

static void bc_read_line(BcVec *vec)
{
        bool bad_chars;

        do {
                int c;

                bad_chars = 0;
                bc_vec_pop_all(vec);

                fflush_and_check();

#if ENABLE_FEATURE_BC_SIGNALS
                if (G_interrupt) { // ^C was pressed
 intr:
                        G_interrupt = 0;
                        // GNU bc says "interrupted execution."
                        // GNU dc says "Interrupt!"
                        fputs("\ninterrupted execution\n", stderr);
                }
# if ENABLE_FEATURE_EDITING
                if (G_ttyin) {
                        int n, i;
#  define line_buf bb_common_bufsiz1
                        n = read_line_input(G.line_input_state, "", line_buf, COMMON_BUFSIZE);
                        if (n <= 0) { // read errors or EOF, or ^D, or ^C
                                if (n == 0) // ^C
                                        goto intr;
                                break;
                        }
                        i = 0;
                        for (;;) {
                                c = line_buf[i++];
                                if (!c) break;
                                bad_chars |= push_input_byte(vec, c);
                        }
#  undef line_buf
                } else
# endif
#endif
                {
                        IF_FEATURE_BC_SIGNALS(errno = 0;)
                        do {
                                c = fgetc(stdin);
#if ENABLE_FEATURE_BC_SIGNALS && !ENABLE_FEATURE_EDITING
                                // Both conditions appear simultaneously, check both just in case
                                if (errno == EINTR || G_interrupt) {
                                        // ^C was pressed
                                        clearerr(stdin);
                                        goto intr;
                                }
#endif
                                if (c == EOF) {
                                        if (ferror(stdin))
                                                quit(); // this emits error message
                                        // Note: EOF does not append '\n', therefore:
                                        // printf 'print 123\n' | bc - works
                                        // printf 'print 123' | bc   - fails (syntax error)
                                        break;
                                }
                                bad_chars |= push_input_byte(vec, c);
                        } while (c != '\n');
                }
        } while (bad_chars);

        bc_vec_pushZeroByte(vec);
}

static char* bc_read_file(const char *path)
{
        char *buf;
        size_t size = ((size_t) -1);
        size_t i;

        // Never returns NULL (dies on errors)
        buf = xmalloc_xopen_read_close(path, &size);

        for (i = 0; i < size; ++i) {
                char c = buf[i];
                if ((c < ' ' && c != '\t' && c != '\r' && c != '\n') // also allow '\v' '\f'?
                 || c > 0x7e
                ) {
                        free(buf);
                        buf = NULL;
                        break;
                }
        }

        return buf;
}

static void bc_num_setToZero(BcNum *n, size_t scale)
{
        n->len = 0;
        n->neg = false;
        n->rdx = scale;
}

static void bc_num_zero(BcNum *n)
{
        bc_num_setToZero(n, 0);
}

static void bc_num_one(BcNum *n)
{
        bc_num_setToZero(n, 0);
        n->len = 1;
        n->num[0] = 1;
}

static void bc_num_ten(BcNum *n)
{
        bc_num_setToZero(n, 0);
        n->len = 2;
        n->num[0] = 0;
        n->num[1] = 1;
}

// Note: this also sets BcNum to zero
static void bc_num_init(BcNum *n, size_t req)
{
        req = req >= BC_NUM_DEF_SIZE ? req : BC_NUM_DEF_SIZE;
        //memset(n, 0, sizeof(BcNum)); - cleared by assignments below
        n->num = xmalloc(req);
        n->cap = req;
        n->rdx = 0;
        n->len = 0;
        n->neg = false;
}

static void bc_num_init_DEF_SIZE(BcNum *n)
{
        bc_num_init(n, BC_NUM_DEF_SIZE);
}

static void bc_num_expand(BcNum *n, size_t req)
{
        req = req >= BC_NUM_DEF_SIZE ? req : BC_NUM_DEF_SIZE;
        if (req > n->cap) {
                n->num = xrealloc(n->num, req);
                n->cap = req;
        }
}

static FAST_FUNC void bc_num_free(void *num)
{
        free(((BcNum *) num)->num);
}

static void bc_num_copy(BcNum *d, BcNum *s)
{
        if (d != s) {
                bc_num_expand(d, s->cap);
                d->len = s->len;
                d->neg = s->neg;
                d->rdx = s->rdx;
                memcpy(d->num, s->num, sizeof(BcDig) * d->len);
        }
}

static BC_STATUS zbc_num_ulong(BcNum *n, unsigned long *result_p)
{
        size_t i;
        unsigned long pow, result;

        if (n->neg) RETURN_STATUS(bc_error("negative number"));

        for (result = 0, pow = 1, i = n->rdx; i < n->len; ++i) {

                unsigned long prev = result, powprev = pow;

                result += ((unsigned long) n->num[i]) * pow;
                pow *= 10;

                if (result < prev || pow < powprev)
                        RETURN_STATUS(bc_error("overflow"));
                prev = result;
                powprev = pow;
        }
        *result_p = result;

        RETURN_STATUS(BC_STATUS_SUCCESS);
}
#if ERRORS_ARE_FATAL
# define zbc_num_ulong(...) (zbc_num_ulong(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static void bc_num_ulong2num(BcNum *n, unsigned long val)
{
        BcDig *ptr;

        bc_num_zero(n);

        if (val == 0) return;

        if (ULONG_MAX == 0xffffffffUL)
                bc_num_expand(n, 10); // 10 digits: 4294967295
        if (ULONG_MAX == 0xffffffffffffffffULL)
                bc_num_expand(n, 20); // 20 digits: 18446744073709551615
        BUILD_BUG_ON(ULONG_MAX > 0xffffffffffffffffULL);

        ptr = n->num;
        for (;;) {
                n->len++;
                *ptr++ = val % 10;
                val /= 10;
                if (val == 0) break;
        }
}

static void bc_num_subArrays(BcDig *restrict a, BcDig *restrict b,
                                 size_t len)
{
        size_t i, j;
        for (i = 0; i < len; ++i) {
                for (a[i] -= b[i], j = 0; a[i + j] < 0;) {
                        a[i + j++] += 10;
                        a[i + j] -= 1;
                }
        }
}

static ssize_t bc_num_compare(BcDig *restrict a, BcDig *restrict b, size_t len)
{
        size_t i;
        int c = 0;
        for (i = len - 1; i < len && !(c = a[i] - b[i]); --i);
        return BC_NUM_NEG(i + 1, c < 0);
}

static ssize_t bc_num_cmp(BcNum *a, BcNum *b)
{
        size_t i, min, a_int, b_int, diff;
        BcDig *max_num, *min_num;
        bool a_max, neg;
        ssize_t cmp;

        if (a == b) return 0;
        if (a->len == 0) return BC_NUM_NEG(!!b->len, !b->neg);
        if (b->len == 0) return BC_NUM_NEG(1, a->neg);

        if (a->neg != b->neg) // signs of a and b differ
                // +a,-b = a>b = 1 or -a,+b = a<b = -1
                return (int)b->neg - (int)a->neg;
        neg = a->neg; // 1 if both negative, 0 if both positive

        a_int = BC_NUM_INT(a);
        b_int = BC_NUM_INT(b);
        a_int -= b_int;

        if (a_int != 0) return (ssize_t) a_int;

        a_max = (a->rdx > b->rdx);
        if (a_max) {
                min = b->rdx;
                diff = a->rdx - b->rdx;
                max_num = a->num + diff;
                min_num = b->num;
                // neg = (a_max == neg); - NOP (maps 1->1 and 0->0)
        } else {
                min = a->rdx;
                diff = b->rdx - a->rdx;
                max_num = b->num + diff;
                min_num = a->num;
                neg = !neg; // same as "neg = (a_max == neg)"
        }

        cmp = bc_num_compare(max_num, min_num, b_int + min);
        if (cmp != 0) return BC_NUM_NEG(cmp, neg);

        for (max_num -= diff, i = diff - 1; i < diff; --i) {
                if (max_num[i]) return BC_NUM_NEG(1, neg);
        }

        return 0;
}

static void bc_num_truncate(BcNum *n, size_t places)
{
        if (places == 0) return;

        n->rdx -= places;

        if (n->len != 0) {
                n->len -= places;
                memmove(n->num, n->num + places, n->len * sizeof(BcDig));
        }
}

static void bc_num_extend(BcNum *n, size_t places)
{
        size_t len = n->len + places;

        if (places != 0) {

                if (n->cap < len) bc_num_expand(n, len);

                memmove(n->num + places, n->num, sizeof(BcDig) * n->len);
                memset(n->num, 0, sizeof(BcDig) * places);

                n->len += places;
                n->rdx += places;
        }
}

static void bc_num_clean(BcNum *n)
{
        while (n->len > 0 && n->num[n->len - 1] == 0) --n->len;
        if (n->len == 0)
                n->neg = false;
        else if (n->len < n->rdx)
                n->len = n->rdx;
}

static void bc_num_retireMul(BcNum *n, size_t scale, bool neg1, bool neg2)
{
        if (n->rdx < scale)
                bc_num_extend(n, scale - n->rdx);
        else
                bc_num_truncate(n, n->rdx - scale);

        bc_num_clean(n);
        if (n->len != 0) n->neg = !neg1 != !neg2;
}

static void bc_num_split(BcNum *restrict n, size_t idx, BcNum *restrict a,
                         BcNum *restrict b)
{
        if (idx < n->len) {

                b->len = n->len - idx;
                a->len = idx;
                a->rdx = b->rdx = 0;

                memcpy(b->num, n->num + idx, b->len * sizeof(BcDig));
                memcpy(a->num, n->num, idx * sizeof(BcDig));
        }
        else {
                bc_num_zero(b);
                bc_num_copy(a, n);
        }

        bc_num_clean(a);
        bc_num_clean(b);
}

static BC_STATUS zbc_num_shift(BcNum *n, size_t places)
{
        if (places == 0 || n->len == 0) RETURN_STATUS(BC_STATUS_SUCCESS);

        // This check makes sense only if size_t is (much) larger than BC_MAX_NUM.
        if (SIZE_MAX > (BC_MAX_NUM | 0xff)) {
                if (places + n->len > BC_MAX_NUM)
                        RETURN_STATUS(bc_error("number too long: must be [1,"BC_MAX_NUM_STR"]"));
        }

        if (n->rdx >= places)
                n->rdx -= places;
        else {
                bc_num_extend(n, places - n->rdx);
                n->rdx = 0;
        }

        bc_num_clean(n);

        RETURN_STATUS(BC_STATUS_SUCCESS);
}
#if ERRORS_ARE_FATAL
# define zbc_num_shift(...) (zbc_num_shift(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_num_inv(BcNum *a, BcNum *b, size_t scale)
{
        BcNum one;
        BcDig num[2];

        one.cap = 2;
        one.num = num;
        bc_num_one(&one);

        RETURN_STATUS(zbc_num_div(&one, a, b, scale));
}
#if ERRORS_ARE_FATAL
# define zbc_num_inv(...) (zbc_num_inv(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static FAST_FUNC BC_STATUS zbc_num_a(BcNum *a, BcNum *b, BcNum *restrict c, size_t sub)
{
        BcDig *ptr, *ptr_a, *ptr_b, *ptr_c;
        size_t i, max, min_rdx, min_int, diff, a_int, b_int;
        int carry, in;

        // Because this function doesn't need to use scale (per the bc spec),
        // I am hijacking it to say whether it's doing an add or a subtract.

        if (a->len == 0) {
                bc_num_copy(c, b);
                if (sub && c->len) c->neg = !c->neg;
                RETURN_STATUS(BC_STATUS_SUCCESS);
        }
        if (b->len == 0) {
                bc_num_copy(c, a);
                RETURN_STATUS(BC_STATUS_SUCCESS);
        }

        c->neg = a->neg;
        c->rdx = BC_MAX(a->rdx, b->rdx);
        min_rdx = BC_MIN(a->rdx, b->rdx);
        c->len = 0;

        if (a->rdx > b->rdx) {
                diff = a->rdx - b->rdx;
                ptr = a->num;
                ptr_a = a->num + diff;
                ptr_b = b->num;
        }
        else {
                diff = b->rdx - a->rdx;
                ptr = b->num;
                ptr_a = a->num;
                ptr_b = b->num + diff;
        }

        for (ptr_c = c->num, i = 0; i < diff; ++i, ++c->len) ptr_c[i] = ptr[i];

        ptr_c += diff;
        a_int = BC_NUM_INT(a);
        b_int = BC_NUM_INT(b);

        if (a_int > b_int) {
                min_int = b_int;
                max = a_int;
                ptr = ptr_a;
        }
        else {
                min_int = a_int;
                max = b_int;
                ptr = ptr_b;
        }

        for (carry = 0, i = 0; i < min_rdx + min_int; ++i, ++c->len) {
                in = ((int) ptr_a[i]) + ((int) ptr_b[i]) + carry;
                carry = in / 10;
                ptr_c[i] = (BcDig)(in % 10);
        }

        for (; i < max + min_rdx; ++i, ++c->len) {
                in = ((int) ptr[i]) + carry;
                carry = in / 10;
                ptr_c[i] = (BcDig)(in % 10);
        }

        if (carry != 0) c->num[c->len++] = (BcDig) carry;

        RETURN_STATUS(BC_STATUS_SUCCESS); // can't make void, see zbc_num_binary()
}

static FAST_FUNC BC_STATUS zbc_num_s(BcNum *a, BcNum *b, BcNum *restrict c, size_t sub)
{
        ssize_t cmp;
        BcNum *minuend, *subtrahend;
        size_t start;
        bool aneg, bneg, neg;

        // Because this function doesn't need to use scale (per the bc spec),
        // I am hijacking it to say whether it's doing an add or a subtract.

        if (a->len == 0) {
                bc_num_copy(c, b);
                if (sub && c->len) c->neg = !c->neg;
                RETURN_STATUS(BC_STATUS_SUCCESS);
        }
        if (b->len == 0) {
                bc_num_copy(c, a);
                RETURN_STATUS(BC_STATUS_SUCCESS);
        }

        aneg = a->neg;
        bneg = b->neg;
        a->neg = b->neg = false;

        cmp = bc_num_cmp(a, b);

        a->neg = aneg;
        b->neg = bneg;

        if (cmp == 0) {
                bc_num_setToZero(c, BC_MAX(a->rdx, b->rdx));
                RETURN_STATUS(BC_STATUS_SUCCESS);
        }
        if (cmp > 0) {
                neg = a->neg;
                minuend = a;
                subtrahend = b;
        }
        else {
                neg = b->neg;
                if (sub) neg = !neg;
                minuend = b;
                subtrahend = a;
        }

        bc_num_copy(c, minuend);
        c->neg = neg;

        if (c->rdx < subtrahend->rdx) {
                bc_num_extend(c, subtrahend->rdx - c->rdx);
                start = 0;
        }
        else
                start = c->rdx - subtrahend->rdx;

        bc_num_subArrays(c->num + start, subtrahend->num, subtrahend->len);

        bc_num_clean(c);

        RETURN_STATUS(BC_STATUS_SUCCESS); // can't make void, see zbc_num_binary()
}

static FAST_FUNC BC_STATUS zbc_num_k(BcNum *restrict a, BcNum *restrict b,
                         BcNum *restrict c)
#if ERRORS_ARE_FATAL
# define zbc_num_k(...) (zbc_num_k(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif
{
        BcStatus s;
        size_t max = BC_MAX(a->len, b->len), max2 = (max + 1) / 2;
        BcNum l1, h1, l2, h2, m2, m1, z0, z1, z2, temp;
        bool aone;

        if (a->len == 0 || b->len == 0) {
                bc_num_zero(c);
                RETURN_STATUS(BC_STATUS_SUCCESS);
        }
        aone = BC_NUM_ONE(a);
        if (aone || BC_NUM_ONE(b)) {
                bc_num_copy(c, aone ? b : a);
                RETURN_STATUS(BC_STATUS_SUCCESS);
        }

        if (a->len + b->len < BC_NUM_KARATSUBA_LEN ||
            a->len < BC_NUM_KARATSUBA_LEN || b->len < BC_NUM_KARATSUBA_LEN)
        {
                size_t i, j, len;
                unsigned carry;

                bc_num_expand(c, a->len + b->len + 1);

                memset(c->num, 0, sizeof(BcDig) * c->cap);
                c->len = len = 0;

                for (i = 0; i < b->len; ++i) {

                        carry = 0;
                        for (j = 0; j < a->len; ++j) {
                                unsigned in = c->num[i + j];
                                in += ((unsigned) a->num[j]) * ((unsigned) b->num[i]) + carry;
                                // note: compilers prefer _unsigned_ div/const
                                carry = in / 10;
                                c->num[i + j] = (BcDig)(in % 10);
                        }

                        c->num[i + j] += (BcDig) carry;
                        len = BC_MAX(len, i + j + !!carry);

#if ENABLE_FEATURE_BC_SIGNALS
                        // a=2^1000000
                        // a*a <- without check below, this will not be interruptible
                        if (G_interrupt) return BC_STATUS_FAILURE;
#endif
                }

                c->len = len;

                RETURN_STATUS(BC_STATUS_SUCCESS);
        }

        bc_num_init(&l1, max);
        bc_num_init(&h1, max);
        bc_num_init(&l2, max);
        bc_num_init(&h2, max);
        bc_num_init(&m1, max);
        bc_num_init(&m2, max);
        bc_num_init(&z0, max);
        bc_num_init(&z1, max);
        bc_num_init(&z2, max);
        bc_num_init(&temp, max + max);

        bc_num_split(a, max2, &l1, &h1);
        bc_num_split(b, max2, &l2, &h2);

        s = zbc_num_add(&h1, &l1, &m1, 0);
        if (s) goto err;
        s = zbc_num_add(&h2, &l2, &m2, 0);
        if (s) goto err;

        s = zbc_num_k(&h1, &h2, &z0);
        if (s) goto err;
        s = zbc_num_k(&m1, &m2, &z1);
        if (s) goto err;
        s = zbc_num_k(&l1, &l2, &z2);
        if (s) goto err;

        s = zbc_num_sub(&z1, &z0, &temp, 0);
        if (s) goto err;
        s = zbc_num_sub(&temp, &z2, &z1, 0);
        if (s) goto err;

        s = zbc_num_shift(&z0, max2 * 2);
        if (s) goto err;
        s = zbc_num_shift(&z1, max2);
        if (s) goto err;
        s = zbc_num_add(&z0, &z1, &temp, 0);
        if (s) goto err;
        s = zbc_num_add(&temp, &z2, c, 0);

err:
        bc_num_free(&temp);
        bc_num_free(&z2);
        bc_num_free(&z1);
        bc_num_free(&z0);
        bc_num_free(&m2);
        bc_num_free(&m1);
        bc_num_free(&h2);
        bc_num_free(&l2);
        bc_num_free(&h1);
        bc_num_free(&l1);
        RETURN_STATUS(s);
}

static FAST_FUNC BC_STATUS zbc_num_m(BcNum *a, BcNum *b, BcNum *restrict c, size_t scale)
{
        BcStatus s;
        BcNum cpa, cpb;
        size_t maxrdx = BC_MAX(a->rdx, b->rdx);

        scale = BC_MAX(scale, a->rdx);
        scale = BC_MAX(scale, b->rdx);
        scale = BC_MIN(a->rdx + b->rdx, scale);
        maxrdx = BC_MAX(maxrdx, scale);

        bc_num_init(&cpa, a->len);
        bc_num_init(&cpb, b->len);

        bc_num_copy(&cpa, a);
        bc_num_copy(&cpb, b);
        cpa.neg = cpb.neg = false;

        s = zbc_num_shift(&cpa, maxrdx);
        if (s) goto err;
        s = zbc_num_shift(&cpb, maxrdx);
        if (s) goto err;
        s = zbc_num_k(&cpa, &cpb, c);
        if (s) goto err;

        maxrdx += scale;
        bc_num_expand(c, c->len + maxrdx);

        if (c->len < maxrdx) {
                memset(c->num + c->len, 0, (c->cap - c->len) * sizeof(BcDig));
                c->len += maxrdx;
        }

        c->rdx = maxrdx;
        bc_num_retireMul(c, scale, a->neg, b->neg);

err:
        bc_num_free(&cpb);
        bc_num_free(&cpa);
        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_num_m(...) (zbc_num_m(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static FAST_FUNC BC_STATUS zbc_num_d(BcNum *a, BcNum *b, BcNum *restrict c, size_t scale)
{
        BcStatus s = BC_STATUS_SUCCESS;
        BcDig *n, *p, q;
        size_t len, end, i;
        BcNum cp;
        bool zero = true;

        if (b->len == 0)
                RETURN_STATUS(bc_error("divide by zero"));
        if (a->len == 0) {
                bc_num_setToZero(c, scale);
                RETURN_STATUS(BC_STATUS_SUCCESS);
        }
        if (BC_NUM_ONE(b)) {
                bc_num_copy(c, a);
                bc_num_retireMul(c, scale, a->neg, b->neg);
                RETURN_STATUS(BC_STATUS_SUCCESS);
        }

        bc_num_init(&cp, BC_NUM_MREQ(a, b, scale));
        bc_num_copy(&cp, a);
        len = b->len;

        if (len > cp.len) {
                bc_num_expand(&cp, len + 2);
                bc_num_extend(&cp, len - cp.len);
        }

        if (b->rdx > cp.rdx) bc_num_extend(&cp, b->rdx - cp.rdx);
        cp.rdx -= b->rdx;
        if (scale > cp.rdx) bc_num_extend(&cp, scale - cp.rdx);

        if (b->rdx == b->len) {
                for (i = 0; zero && i < len; ++i) zero = !b->num[len - i - 1];
                len -= i - 1;
        }

        if (cp.cap == cp.len) bc_num_expand(&cp, cp.len + 1);

        // We want an extra zero in front to make things simpler.
        cp.num[cp.len++] = 0;
        end = cp.len - len;

        bc_num_expand(c, cp.len);

        bc_num_zero(c);
        memset(c->num + end, 0, (c->cap - end) * sizeof(BcDig));
        c->rdx = cp.rdx;
        c->len = cp.len;
        p = b->num;

        for (i = end - 1; !s && i < end; --i) {
                n = cp.num + i;
                for (q = 0; (!s && n[len] != 0) || bc_num_compare(n, p, len) >= 0; ++q)
                        bc_num_subArrays(n, p, len);
                c->num[i] = q;
#if ENABLE_FEATURE_BC_SIGNALS
                // a=2^100000
                // scale=40000
                // 1/a <- without check below, this will not be interruptible
                if (G_interrupt) {
                        s = BC_STATUS_FAILURE;
                        break;
                }
#endif
        }

        bc_num_retireMul(c, scale, a->neg, b->neg);
        bc_num_free(&cp);

        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_num_d(...) (zbc_num_d(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static FAST_FUNC BC_STATUS zbc_num_r(BcNum *a, BcNum *b, BcNum *restrict c,
                         BcNum *restrict d, size_t scale, size_t ts)
{
        BcStatus s;
        BcNum temp;
        bool neg;

        if (b->len == 0)
                RETURN_STATUS(bc_error("divide by zero"));

        if (a->len == 0) {
                bc_num_setToZero(d, ts);
                RETURN_STATUS(BC_STATUS_SUCCESS);
        }

        bc_num_init(&temp, d->cap);
        s = zbc_num_d(a, b, c, scale);
        if (s) goto err;

        if (scale != 0) scale = ts;

        s = zbc_num_m(c, b, &temp, scale);
        if (s) goto err;
        s = zbc_num_sub(a, &temp, d, scale);
        if (s) goto err;

        if (ts > d->rdx && d->len) bc_num_extend(d, ts - d->rdx);

        neg = d->neg;
        bc_num_retireMul(d, ts, a->neg, b->neg);
        d->neg = neg;

err:
        bc_num_free(&temp);
        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_num_r(...) (zbc_num_r(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static FAST_FUNC BC_STATUS zbc_num_rem(BcNum *a, BcNum *b, BcNum *restrict c, size_t scale)
{
        BcStatus s;
        BcNum c1;
        size_t ts = BC_MAX(scale + b->rdx, a->rdx), len = BC_NUM_MREQ(a, b, ts);

        bc_num_init(&c1, len);
        s = zbc_num_r(a, b, &c1, c, scale, ts);
        bc_num_free(&c1);

        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_num_rem(...) (zbc_num_rem(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static FAST_FUNC BC_STATUS zbc_num_p(BcNum *a, BcNum *b, BcNum *restrict c, size_t scale)
{
        BcStatus s = BC_STATUS_SUCCESS;
        BcNum copy;
        unsigned long pow;
        size_t i, powrdx, resrdx;
        bool neg, zero;

        if (b->rdx) RETURN_STATUS(bc_error("non integer number"));

        if (b->len == 0) {
                bc_num_one(c);
                RETURN_STATUS(BC_STATUS_SUCCESS);
        }
        if (a->len == 0) {
                bc_num_setToZero(c, scale);
                RETURN_STATUS(BC_STATUS_SUCCESS);
        }
        if (BC_NUM_ONE(b)) {
                if (!b->neg)
                        bc_num_copy(c, a);
                else
                        s = zbc_num_inv(a, c, scale);
                RETURN_STATUS(s);
        }

        neg = b->neg;
        b->neg = false;

        s = zbc_num_ulong(b, &pow);
        if (s) RETURN_STATUS(s);

        bc_num_init(&copy, a->len);
        bc_num_copy(&copy, a);

        if (!neg) {
                if (a->rdx > scale)
                        scale = a->rdx;
                if (a->rdx * pow < scale)
                        scale = a->rdx * pow;
        }

        b->neg = neg;

        for (powrdx = a->rdx; !(pow & 1); pow >>= 1) {
                powrdx <<= 1;
                s = zbc_num_mul(&copy, &copy, &copy, powrdx);
                if (s) goto err;
                // Not needed: zbc_num_mul() has a check for ^C:
                //if (G_interrupt) {
                //      s = BC_STATUS_FAILURE;
                //      goto err;
                //}
        }

        bc_num_copy(c, &copy);

        for (resrdx = powrdx, pow >>= 1; pow != 0; pow >>= 1) {

                powrdx <<= 1;
                s = zbc_num_mul(&copy, &copy, &copy, powrdx);
                if (s) goto err;

                if (pow & 1) {
                        resrdx += powrdx;
                        s = zbc_num_mul(c, &copy, c, resrdx);
                        if (s) goto err;
                }
                // Not needed: zbc_num_mul() has a check for ^C:
                //if (G_interrupt) {
                //      s = BC_STATUS_FAILURE;
                //      goto err;
                //}
        }

        if (neg) {
                s = zbc_num_inv(c, c, scale);
                if (s) goto err;
        }

        if (c->rdx > scale) bc_num_truncate(c, c->rdx - scale);

        // We can't use bc_num_clean() here.
        for (zero = true, i = 0; zero && i < c->len; ++i) zero = !c->num[i];
        if (zero) bc_num_setToZero(c, scale);

err:
        bc_num_free(&copy);
        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_num_p(...) (zbc_num_p(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_num_binary(BcNum *a, BcNum *b, BcNum *c, size_t scale,
                              BcNumBinaryOp op, size_t req)
{
        BcStatus s;
        BcNum num2, *ptr_a, *ptr_b;
        bool init = false;

        if (c == a) {
                ptr_a = &num2;
                memcpy(ptr_a, c, sizeof(BcNum));
                init = true;
        }
        else
                ptr_a = a;

        if (c == b) {
                ptr_b = &num2;
                if (c != a) {
                        memcpy(ptr_b, c, sizeof(BcNum));
                        init = true;
                }
        }
        else
                ptr_b = b;

        if (init)
                bc_num_init(c, req);
        else
                bc_num_expand(c, req);

        s = BC_STATUS_SUCCESS;
        ERROR_RETURN(s =) op(ptr_a, ptr_b, c, scale);

        if (init) bc_num_free(&num2);

        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_num_binary(...) (zbc_num_binary(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static bool bc_num_strValid(const char *val, size_t base)
{
        BcDig b;
        bool radix;

        b = (BcDig)(base <= 10 ? base + '0' : base - 10 + 'A');
        radix = false;
        for (;;) {
                BcDig c = *val++;
                if (c == '\0')
                        break;
                if (c == '.') {
                        if (radix) return false;
                        radix = true;
                        continue;
                }
                if (c < '0' || c >= b || (c > '9' && c < 'A'))
                        return false;
        }
        return true;
}

// Note: n is already "bc_num_zero()"ed,
// leading zeroes in "val" are removed
static void bc_num_parseDecimal(BcNum *n, const char *val)
{
        size_t len, i;
        const char *ptr;

        len = strlen(val);
        if (len == 0)
                return;

        bc_num_expand(n, len);

        ptr = strchr(val, '.');

        n->rdx = 0;
        if (ptr != NULL)
                n->rdx = (size_t)((val + len) - (ptr + 1));

        for (i = 0; val[i]; ++i) {
                if (val[i] != '0' && val[i] != '.') {
                        // Not entirely zero value - convert it, and exit
                        i = len - 1;
                        for (;;) {
                                n->num[n->len] = val[i] - '0';
                                ++n->len;
 skip_dot:
                                if ((ssize_t)--i == (ssize_t)-1) break;
                                if (val[i] == '.') goto skip_dot;
                        }
                        break;
                }
        }
        // if this is reached, the value is entirely zero
}

// Note: n is already "bc_num_zero()"ed,
// leading zeroes in "val" are removed
static void bc_num_parseBase(BcNum *n, const char *val, BcNum *base)
{
        BcStatus s;
        BcNum temp, mult, result;
        BcDig c = '\0';
        unsigned long v;
        size_t i, digits;

        for (i = 0; ; ++i) {
                if (val[i] == '\0')
                        return;
                if (val[i] != '.' && val[i] != '0')
                        break;
        }

        bc_num_init_DEF_SIZE(&temp);
        bc_num_init_DEF_SIZE(&mult);

        for (;;) {
                c = *val++;
                if (c == '\0') goto int_err;
                if (c == '.') break;

                v = (unsigned long) (c <= '9' ? c - '0' : c - 'A' + 10);

                s = zbc_num_mul(n, base, &mult, 0);
                if (s) goto int_err;
                bc_num_ulong2num(&temp, v);
                s = zbc_num_add(&mult, &temp, n, 0);
                if (s) goto int_err;
        }

        bc_num_init(&result, base->len);
        //bc_num_zero(&result); - already is
        bc_num_one(&mult);

        digits = 0;
        for (;;) {
                c = *val++;
                if (c == '\0') break;
                digits++;

                v = (unsigned long) (c <= '9' ? c - '0' : c - 'A' + 10);

                s = zbc_num_mul(&result, base, &result, 0);
                if (s) goto err;
                bc_num_ulong2num(&temp, v);
                s = zbc_num_add(&result, &temp, &result, 0);
                if (s) goto err;
                s = zbc_num_mul(&mult, base, &mult, 0);
                if (s) goto err;
        }

        s = zbc_num_div(&result, &mult, &result, digits);
        if (s) goto err;
        s = zbc_num_add(n, &result, n, digits);
        if (s) goto err;

        if (n->len != 0) {
                if (n->rdx < digits) bc_num_extend(n, digits - n->rdx);
        } else
                bc_num_zero(n);

err:
        bc_num_free(&result);
int_err:
        bc_num_free(&mult);
        bc_num_free(&temp);
}

static BC_STATUS zbc_num_parse(BcNum *n, const char *val, BcNum *base,
                             size_t base_t)
{
        if (!bc_num_strValid(val, base_t))
                RETURN_STATUS(bc_error("bad number string"));

        bc_num_zero(n);
        while (*val == '0') val++;

        if (base_t == 10)
                bc_num_parseDecimal(n, val);
        else
                bc_num_parseBase(n, val, base);

        RETURN_STATUS(BC_STATUS_SUCCESS);
}
#if ERRORS_ARE_FATAL
# define zbc_num_parse(...) (zbc_num_parse(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_num_sqrt(BcNum *a, BcNum *restrict b, size_t scale)
{
        BcStatus s;
        BcNum num1, num2, half, f, fprime, *x0, *x1, *temp;
        size_t pow, len, digs, digs1, resrdx, req, times = 0;
        ssize_t cmp = 1, cmp1 = SSIZE_MAX, cmp2 = SSIZE_MAX;

        req = BC_MAX(scale, a->rdx) + ((BC_NUM_INT(a) + 1) >> 1) + 1;
        bc_num_expand(b, req);

        if (a->len == 0) {
                bc_num_setToZero(b, scale);
                RETURN_STATUS(BC_STATUS_SUCCESS);
        }
        else if (a->neg)
                RETURN_STATUS(bc_error("negative number"));
        else if (BC_NUM_ONE(a)) {
                bc_num_one(b);
                bc_num_extend(b, scale);
                RETURN_STATUS(BC_STATUS_SUCCESS);
        }

        scale = BC_MAX(scale, a->rdx) + 1;
        len = a->len + scale;

        bc_num_init(&num1, len);
        bc_num_init(&num2, len);
        bc_num_init_DEF_SIZE(&half);

        bc_num_one(&half);
        half.num[0] = 5;
        half.rdx = 1;

        bc_num_init(&f, len);
        bc_num_init(&fprime, len);

        x0 = &num1;
        x1 = &num2;

        bc_num_one(x0);
        pow = BC_NUM_INT(a);

        if (pow) {

                if (pow & 1)
                        x0->num[0] = 2;
                else
                        x0->num[0] = 6;

                pow -= 2 - (pow & 1);

                bc_num_extend(x0, pow);

                // Make sure to move the radix back.
                x0->rdx -= pow;
        }

        x0->rdx = digs = digs1 = 0;
        resrdx = scale + 2;
        len = BC_NUM_INT(x0) + resrdx - 1;

        while (cmp != 0 || digs < len) {

                s = zbc_num_div(a, x0, &f, resrdx);
                if (s) goto err;
                s = zbc_num_add(x0, &f, &fprime, resrdx);
                if (s) goto err;
                s = zbc_num_mul(&fprime, &half, x1, resrdx);
                if (s) goto err;

                cmp = bc_num_cmp(x1, x0);
                digs = x1->len - (unsigned long long) llabs(cmp);

                if (cmp == cmp2 && digs == digs1)
                        times += 1;
                else
                        times = 0;

                resrdx += times > 4;

                cmp2 = cmp1;
                cmp1 = cmp;
                digs1 = digs;

                temp = x0;
                x0 = x1;
                x1 = temp;
        }

        bc_num_copy(b, x0);
        scale -= 1;
        if (b->rdx > scale) bc_num_truncate(b, b->rdx - scale);

err:
        bc_num_free(&fprime);
        bc_num_free(&f);
        bc_num_free(&half);
        bc_num_free(&num2);
        bc_num_free(&num1);
        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_num_sqrt(...) (zbc_num_sqrt(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_num_divmod(BcNum *a, BcNum *b, BcNum *c, BcNum *d,
                              size_t scale)
{
        BcStatus s;
        BcNum num2, *ptr_a;
        bool init = false;
        size_t ts = BC_MAX(scale + b->rdx, a->rdx), len = BC_NUM_MREQ(a, b, ts);

        if (c == a) {
                memcpy(&num2, c, sizeof(BcNum));
                ptr_a = &num2;
                bc_num_init(c, len);
                init = true;
        }
        else {
                ptr_a = a;
                bc_num_expand(c, len);
        }

        s = zbc_num_r(ptr_a, b, c, d, scale, ts);

        if (init) bc_num_free(&num2);

        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_num_divmod(...) (zbc_num_divmod(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

#if ENABLE_DC
static BC_STATUS zbc_num_modexp(BcNum *a, BcNum *b, BcNum *c, BcNum *restrict d)
{
        BcStatus s;
        BcNum base, exp, two, temp;

        if (c->len == 0)
                RETURN_STATUS(bc_error("divide by zero"));
        if (a->rdx || b->rdx || c->rdx)
                RETURN_STATUS(bc_error("non integer number"));
        if (b->neg)
                RETURN_STATUS(bc_error("negative number"));

        bc_num_expand(d, c->len);
        bc_num_init(&base, c->len);
        bc_num_init(&exp, b->len);
        bc_num_init_DEF_SIZE(&two);
        bc_num_init(&temp, b->len);

        bc_num_one(&two);
        two.num[0] = 2;
        bc_num_one(d);

        s = zbc_num_rem(a, c, &base, 0);
        if (s) goto err;
        bc_num_copy(&exp, b);

        while (exp.len != 0) {

                s = zbc_num_divmod(&exp, &two, &exp, &temp, 0);
                if (s) goto err;

                if (BC_NUM_ONE(&temp)) {
                        s = zbc_num_mul(d, &base, &temp, 0);
                        if (s) goto err;
                        s = zbc_num_rem(&temp, c, d, 0);
                        if (s) goto err;
                }

                s = zbc_num_mul(&base, &base, &temp, 0);
                if (s) goto err;
                s = zbc_num_rem(&temp, c, &base, 0);
                if (s) goto err;
        }

err:
        bc_num_free(&temp);
        bc_num_free(&two);
        bc_num_free(&exp);
        bc_num_free(&base);
        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_num_modexp(...) (zbc_num_modexp(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif
#endif // ENABLE_DC

#if ENABLE_BC
static BC_STATUS zbc_func_insert(BcFunc *f, char *name, bool var)
{
        BcId a;
        size_t i;

        for (i = 0; i < f->autos.len; ++i) {
                if (strcmp(name, ((BcId *) bc_vec_item(&f->autos, i))->name) == 0)
                        RETURN_STATUS(bc_error("function parameter or auto var has the same name as another"));
        }

        a.idx = var;
        a.name = name;

        bc_vec_push(&f->autos, &a);

        RETURN_STATUS(BC_STATUS_SUCCESS);
}
#if ERRORS_ARE_FATAL
# define zbc_func_insert(...) (zbc_func_insert(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif
#endif

static void bc_func_init(BcFunc *f)
{
        bc_char_vec_init(&f->code);
        bc_vec_init(&f->autos, sizeof(BcId), bc_id_free);
        bc_vec_init(&f->labels, sizeof(size_t), NULL);
        f->nparams = 0;
}

static FAST_FUNC void bc_func_free(void *func)
{
        BcFunc *f = (BcFunc *) func;
        bc_vec_free(&f->code);
        bc_vec_free(&f->autos);
        bc_vec_free(&f->labels);
}

static void bc_array_expand(BcVec *a, size_t len);

static void bc_array_init(BcVec *a, bool nums)
{
        if (nums)
                bc_vec_init(a, sizeof(BcNum), bc_num_free);
        else
                bc_vec_init(a, sizeof(BcVec), bc_vec_free);
        bc_array_expand(a, 1);
}

static void bc_array_expand(BcVec *a, size_t len)
{
        BcResultData data;

        if (a->size == sizeof(BcNum) && a->dtor == bc_num_free) {
                while (len > a->len) {
                        bc_num_init_DEF_SIZE(&data.n);
                        bc_vec_push(a, &data.n);
                }
        }
        else {
                while (len > a->len) {
                        bc_array_init(&data.v, true);
                        bc_vec_push(a, &data.v);
                }
        }
}

static void bc_array_copy(BcVec *d, const BcVec *s)
{
        size_t i;

        bc_vec_pop_all(d);
        bc_vec_expand(d, s->cap);
        d->len = s->len;

        for (i = 0; i < s->len; ++i) {
                BcNum *dnum = bc_vec_item(d, i), *snum = bc_vec_item(s, i);
                bc_num_init(dnum, snum->len);
                bc_num_copy(dnum, snum);
        }
}

static FAST_FUNC void bc_string_free(void *string)
{
        free(*((char **) string));
}

#if ENABLE_DC
static void bc_result_copy(BcResult *d, BcResult *src)
{
        d->t = src->t;

        switch (d->t) {

                case BC_RESULT_TEMP:
                case BC_RESULT_IBASE:
                case BC_RESULT_SCALE:
                case BC_RESULT_OBASE:
                {
                        bc_num_init(&d->d.n, src->d.n.len);
                        bc_num_copy(&d->d.n, &src->d.n);
                        break;
                }

                case BC_RESULT_VAR:
                case BC_RESULT_ARRAY:
                case BC_RESULT_ARRAY_ELEM:
                {
                        d->d.id.name = xstrdup(src->d.id.name);
                        break;
                }

                case BC_RESULT_CONSTANT:
                case BC_RESULT_LAST:
                case BC_RESULT_ONE:
                case BC_RESULT_STR:
                {
                        memcpy(&d->d.n, &src->d.n, sizeof(BcNum));
                        break;
                }
        }
}
#endif // ENABLE_DC

static FAST_FUNC void bc_result_free(void *result)
{
        BcResult *r = (BcResult *) result;

        switch (r->t) {

                case BC_RESULT_TEMP:
                case BC_RESULT_IBASE:
                case BC_RESULT_SCALE:
                case BC_RESULT_OBASE:
                {
                        bc_num_free(&r->d.n);
                        break;
                }

                case BC_RESULT_VAR:
                case BC_RESULT_ARRAY:
                case BC_RESULT_ARRAY_ELEM:
                {
                        free(r->d.id.name);
                        break;
                }

                default:
                {
                        // Do nothing.
                        break;
                }
        }
}

static void bc_lex_lineComment(BcLex *l)
{
        l->t.t = BC_LEX_WHITESPACE;
        while (l->i < l->len && l->buf[l->i++] != '\n');
        --l->i;
}

static void bc_lex_whitespace(BcLex *l)
{
        char c;
        l->t.t = BC_LEX_WHITESPACE;
        for (c = l->buf[l->i]; c != '\n' && isspace(c); c = l->buf[++l->i]);
}

static BC_STATUS zbc_lex_number(BcLex *l, char start)
{
        const char *buf = l->buf + l->i;
        size_t len, bslashes, i, ccnt;
        bool pt;

        pt = (start == '.');
        l->t.t = BC_LEX_NUMBER;
        bslashes = 0;
        ccnt = i = 0;
        for (;;) {
                char c = buf[i];
                if (c == '\0')
                        break;
                if (c == '\\' && buf[i + 1] == '\n') {
                        i += 2;
                        bslashes++;
                        continue;
                }
                if (!isdigit(c) && (c < 'A' || c > 'F')) {
                        if (c != '.') break;
                        // if '.' was already seen, stop on second one:
                        if (pt) break;
                        pt = 1;
                }
                // buf[i] is one of "0-9A-F."
                i++;
                if (c != '.')
                        ccnt = i;
        }
        //i is buf[i] index of the first not-yet-parsed char
        l->i += i;

        //ccnt is the number of chars in the number string, excluding possible
        //trailing "." and possible following trailing "\<newline>"(s).
        len = ccnt - bslashes * 2 + 1; // +1 byte for NUL termination

        // This check makes sense only if size_t is (much) larger than BC_MAX_NUM.
        if (SIZE_MAX > (BC_MAX_NUM | 0xff)) {
                if (len > BC_MAX_NUM)
                        RETURN_STATUS(bc_error("number too long: must be [1,"BC_MAX_NUM_STR"]"));
        }

        bc_vec_pop_all(&l->t.v);
        bc_vec_expand(&l->t.v, 1 + len);
        bc_vec_push(&l->t.v, &start);

        while (ccnt != 0) {
                // If we have hit a backslash, skip it. We don't have
                // to check for a newline because it's guaranteed.
                if (*buf == '\\') {
                        buf += 2;
                        ccnt -= 2;
                        continue;
                }
                bc_vec_push(&l->t.v, buf);
                buf++;
                ccnt--;
        }

        bc_vec_pushZeroByte(&l->t.v);

        RETURN_STATUS(BC_STATUS_SUCCESS);
}
#if ERRORS_ARE_FATAL
# define zbc_lex_number(...) (zbc_lex_number(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static void bc_lex_name(BcLex *l)
{
        size_t i;
        const char *buf;

        l->t.t = BC_LEX_NAME;

        i = 0;
        buf = l->buf + l->i - 1;
        for (;;) {
                char c = buf[i];
                if ((c < 'a' || c > 'z') && !isdigit(c) && c != '_') break;
                i++;
        }

#if 0 // We do not protect against people with gigabyte-long names
        // This check makes sense only if size_t is (much) larger than BC_MAX_STRING.
        if (SIZE_MAX > (BC_MAX_STRING | 0xff)) {
                if (i > BC_MAX_STRING)
                        return bc_error("name too long: must be [1,"BC_MAX_STRING_STR"]");
        }
#endif
        bc_vec_string(&l->t.v, i, buf);

        // Increment the index. We minus 1 because it has already been incremented.
        l->i += i - 1;

        //return BC_STATUS_SUCCESS;
}

static void bc_lex_init(BcLex *l)
{
        bc_char_vec_init(&l->t.v);
}

static void bc_lex_free(BcLex *l)
{
        bc_vec_free(&l->t.v);
}

static void bc_lex_file(BcLex *l)
{
        G.err_line = l->line = 1;
        l->newline = false;
}

static BC_STATUS zbc_lex_token(BcLex *l);
static BC_STATUS zdc_lex_token(BcLex *l);

static BC_STATUS zcommon_lex_token(BcLex *l)
{
        if (IS_BC) {
                IF_BC(RETURN_STATUS(zbc_lex_token(l));)
        }
        IF_DC(RETURN_STATUS(zdc_lex_token(l));)
}

static BC_STATUS zbc_lex_next(BcLex *l)
{
        BcStatus s;

        l->t.last = l->t.t;
        if (l->t.last == BC_LEX_EOF) RETURN_STATUS(bc_error("end of file"));

        l->line += l->newline;
        G.err_line = l->line;
        l->t.t = BC_LEX_EOF;

        l->newline = (l->i == l->len);
        if (l->newline) RETURN_STATUS(BC_STATUS_SUCCESS);

        // Loop until failure or we don't have whitespace. This
        // is so the parser doesn't get inundated with whitespace.
        s = BC_STATUS_SUCCESS;
        do {
//TODO: replace pointer with if(IS_BC)
                ERROR_RETURN(s =) zcommon_lex_token(l);
        } while (!s && l->t.t == BC_LEX_WHITESPACE);

        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_lex_next(...) (zbc_lex_next(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_lex_text(BcLex *l, const char *text)
{
        l->buf = text;
        l->i = 0;
        l->len = strlen(text);
        l->t.t = l->t.last = BC_LEX_INVALID;
        RETURN_STATUS(zbc_lex_next(l));
}
#if ERRORS_ARE_FATAL
# define zbc_lex_text(...) (zbc_lex_text(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

#if ENABLE_BC
static BC_STATUS zbc_lex_identifier(BcLex *l)
{
        BcStatus s;
        unsigned i;
        const char *buf = l->buf + l->i - 1;

        for (i = 0; i < ARRAY_SIZE(bc_lex_kws); ++i) {
                const char *keyword8 = bc_lex_kws[i].name8;
                unsigned j = 0;
                while (buf[j] != '\0' && buf[j] == keyword8[j]) {
                        j++;
                        if (j == 8) goto match;
                }
                if (keyword8[j] != '\0')
                        continue;
 match:
                // buf starts with keyword bc_lex_kws[i]
                l->t.t = BC_LEX_KEY_1st_keyword + i;
                if (!bc_lex_kws_POSIX(i)) {
                        s = bc_posix_error_fmt("%sthe '%.8s' keyword", "POSIX does not allow ", bc_lex_kws[i].name8);
                        ERROR_RETURN(if (s) RETURN_STATUS(s);)
                }

                // We minus 1 because the index has already been incremented.
                l->i += j - 1;
                RETURN_STATUS(BC_STATUS_SUCCESS);
        }

        bc_lex_name(l);

        if (l->t.v.len > 2) {
                // Prevent this:
                // >>> qwe=1
                // bc: POSIX only allows one character names; the following is bad: 'qwe=1
                // '
                unsigned len = strchrnul(buf, '\n') - buf;
                s = bc_posix_error_fmt("POSIX only allows one character names; the following is bad: '%.*s'", len, buf);
        }

        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_lex_identifier(...) (zbc_lex_identifier(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_lex_string(BcLex *l)
{
        size_t len, nls = 0, i = l->i;
        char c;

        l->t.t = BC_LEX_STR;

        for (c = l->buf[i]; c != 0 && c != '"'; c = l->buf[++i])
                nls += (c == '\n');

        if (c == '\0') {
                l->i = i;
                RETURN_STATUS(bc_error("string end could not be found"));
        }

        len = i - l->i;
        // This check makes sense only if size_t is (much) larger than BC_MAX_STRING.
        if (SIZE_MAX > (BC_MAX_STRING | 0xff)) {
                if (len > BC_MAX_STRING)
                        RETURN_STATUS(bc_error("string too long: must be [1,"BC_MAX_STRING_STR"]"));
        }
        bc_vec_string(&l->t.v, len, l->buf + l->i);

        l->i = i + 1;
        l->line += nls;
        G.err_line = l->line;

        RETURN_STATUS(BC_STATUS_SUCCESS);
}
#if ERRORS_ARE_FATAL
# define zbc_lex_string(...) (zbc_lex_string(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static void bc_lex_assign(BcLex *l, BcLexType with, BcLexType without)
{
        if (l->buf[l->i] == '=') {
                ++l->i;
                l->t.t = with;
        }
        else
                l->t.t = without;
}

static BC_STATUS zbc_lex_comment(BcLex *l)
{
        size_t i, nls = 0;
        const char *buf = l->buf;

        l->t.t = BC_LEX_WHITESPACE;
        i = ++l->i;
        for (;;) {
                char c = buf[i];
 check_star:
                if (c == '*') {
                        c = buf[++i];
                        if (c == '/')
                                break;
                        goto check_star;
                }
                if (c == '\0') {
                        l->i = i;
                        RETURN_STATUS(bc_error("comment end could not be found"));
                }
                nls += (c == '\n');
                i++;
        }

        l->i = i + 1;
        l->line += nls;
        G.err_line = l->line;

        RETURN_STATUS(BC_STATUS_SUCCESS);
}
#if ERRORS_ARE_FATAL
# define zbc_lex_comment(...) (zbc_lex_comment(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_lex_token(BcLex *l)
{
        BcStatus s = BC_STATUS_SUCCESS;
        char c = l->buf[l->i++], c2;

        // This is the workhorse of the lexer.
        switch (c) {
                case '\0':
                case '\n':
                        l->newline = true;
                        l->t.t = !c ? BC_LEX_EOF : BC_LEX_NLINE;
                        break;
                case '\t':
                case '\v':
                case '\f':
                case '\r':
                case ' ':
                        bc_lex_whitespace(l);
                        break;
                case '!':
                        bc_lex_assign(l, BC_LEX_OP_REL_NE, BC_LEX_OP_BOOL_NOT);
                        if (l->t.t == BC_LEX_OP_BOOL_NOT) {
                                s = bc_POSIX_does_not_allow_bool_ops_this_is_bad("!");
                                ERROR_RETURN(if (s) RETURN_STATUS(s);)
                        }
                        break;
                case '"':
                        s = zbc_lex_string(l);
                        break;
                case '#':
                        s = bc_POSIX_does_not_allow("'#' script comments");
                        ERROR_RETURN(if (s) RETURN_STATUS(s);)
                        bc_lex_lineComment(l);
                        break;
                case '%':
                        bc_lex_assign(l, BC_LEX_OP_ASSIGN_MODULUS, BC_LEX_OP_MODULUS);
                        break;
                case '&':
                        c2 = l->buf[l->i];
                        if (c2 == '&') {
                                s = bc_POSIX_does_not_allow_bool_ops_this_is_bad("&&");
                                ERROR_RETURN(if (s) RETURN_STATUS(s);)
                                ++l->i;
                                l->t.t = BC_LEX_OP_BOOL_AND;
                        } else {
                                l->t.t = BC_LEX_INVALID;
                                s = bc_error_bad_character('&');
                        }
                        break;
                case '(':
                case ')':
                        l->t.t = (BcLexType)(c - '(' + BC_LEX_LPAREN);
                        break;
                case '*':
                        bc_lex_assign(l, BC_LEX_OP_ASSIGN_MULTIPLY, BC_LEX_OP_MULTIPLY);
                        break;
                case '+':
                        c2 = l->buf[l->i];
                        if (c2 == '+') {
                                ++l->i;
                                l->t.t = BC_LEX_OP_INC;
                        } else
                                bc_lex_assign(l, BC_LEX_OP_ASSIGN_PLUS, BC_LEX_OP_PLUS);
                        break;
                case ',':
                        l->t.t = BC_LEX_COMMA;
                        break;
                case '-':
                        c2 = l->buf[l->i];
                        if (c2 == '-') {
                                ++l->i;
                                l->t.t = BC_LEX_OP_DEC;
                        } else
                                bc_lex_assign(l, BC_LEX_OP_ASSIGN_MINUS, BC_LEX_OP_MINUS);
                        break;
                case '.':
                        if (isdigit(l->buf[l->i]))
                                s = zbc_lex_number(l, c);
                        else {
                                l->t.t = BC_LEX_KEY_LAST;
                                s = bc_POSIX_does_not_allow("a period ('.') as a shortcut for the last result");
                        }
                        break;
                case '/':
                        c2 = l->buf[l->i];
                        if (c2 == '*')
                                s = zbc_lex_comment(l);
                        else
                                bc_lex_assign(l, BC_LEX_OP_ASSIGN_DIVIDE, BC_LEX_OP_DIVIDE);
                        break;
                case '0':
                case '1':
                case '2':
                case '3':
                case '4':
                case '5':
                case '6':
                case '7':
                case '8':
                case '9':
                case 'A':
                case 'B':
                case 'C':
                case 'D':
                case 'E':
                case 'F':
                        s = zbc_lex_number(l, c);
                        break;
                case ';':
                        l->t.t = BC_LEX_SCOLON;
                        break;
                case '<':
                        bc_lex_assign(l, BC_LEX_OP_REL_LE, BC_LEX_OP_REL_LT);
                        break;
                case '=':
                        bc_lex_assign(l, BC_LEX_OP_REL_EQ, BC_LEX_OP_ASSIGN);
                        break;
                case '>':
                        bc_lex_assign(l, BC_LEX_OP_REL_GE, BC_LEX_OP_REL_GT);
                        break;
                case '[':
                case ']':
                        l->t.t = (BcLexType)(c - '[' + BC_LEX_LBRACKET);
                        break;
                case '\\':
                        if (l->buf[l->i] == '\n') {
                                l->t.t = BC_LEX_WHITESPACE;
                                ++l->i;
                        } else
                                s = bc_error_bad_character(c);
                        break;
                case '^':
                        bc_lex_assign(l, BC_LEX_OP_ASSIGN_POWER, BC_LEX_OP_POWER);
                        break;
                case 'a':
                case 'b':
                case 'c':
                case 'd':
                case 'e':
                case 'f':
                case 'g':
                case 'h':
                case 'i':
                case 'j':
                case 'k':
                case 'l':
                case 'm':
                case 'n':
                case 'o':
                case 'p':
                case 'q':
                case 'r':
                case 's':
                case 't':
                case 'u':
                case 'v':
                case 'w':
                case 'x':
                case 'y':
                case 'z':
                        s = zbc_lex_identifier(l);
                        break;
                case '{':
                case '}':
                        l->t.t = (BcLexType)(c - '{' + BC_LEX_LBRACE);
                        break;
                case '|':
                        c2 = l->buf[l->i];
                        if (c2 == '|') {
                                s = bc_POSIX_does_not_allow_bool_ops_this_is_bad("||");
                                ERROR_RETURN(if (s) RETURN_STATUS(s);)
                                ++l->i;
                                l->t.t = BC_LEX_OP_BOOL_OR;
                        } else {
                                l->t.t = BC_LEX_INVALID;
                                s = bc_error_bad_character(c);
                        }
                        break;
                default:
                        l->t.t = BC_LEX_INVALID;
                        s = bc_error_bad_character(c);
                        break;
        }

        RETURN_STATUS(s);
}
#endif // ENABLE_BC

#if ENABLE_DC
static BC_STATUS zdc_lex_register(BcLex *l)
{
        if (isspace(l->buf[l->i - 1])) {
                bc_lex_whitespace(l);
                ++l->i;
                if (!G_exreg)
                        RETURN_STATUS(bc_error("extended register"));
                bc_lex_name(l);
        }
        else {
                bc_vec_pop_all(&l->t.v);
                bc_vec_push(&l->t.v, &l->buf[l->i - 1]);
                bc_vec_pushZeroByte(&l->t.v);
                l->t.t = BC_LEX_NAME;
        }

        RETURN_STATUS(BC_STATUS_SUCCESS);
}
#if ERRORS_ARE_FATAL
# define zdc_lex_register(...) (zdc_lex_register(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zdc_lex_string(BcLex *l)
{
        size_t depth = 1, nls = 0, i = l->i;
        char c;

        l->t.t = BC_LEX_STR;
        bc_vec_pop_all(&l->t.v);

        for (c = l->buf[i]; c != 0 && depth; c = l->buf[++i]) {

                depth += (c == '[' && (i == l->i || l->buf[i - 1] != '\\'));
                depth -= (c == ']' && (i == l->i || l->buf[i - 1] != '\\'));
                nls += (c == '\n');

                if (depth) bc_vec_push(&l->t.v, &c);
        }

        if (c == '\0') {
                l->i = i;
                RETURN_STATUS(bc_error("string end could not be found"));
        }

        bc_vec_pushZeroByte(&l->t.v);
        // This check makes sense only if size_t is (much) larger than BC_MAX_STRING.
        if (SIZE_MAX > (BC_MAX_STRING | 0xff)) {
                if (i - l->i > BC_MAX_STRING)
                        RETURN_STATUS(bc_error("string too long: must be [1,"BC_MAX_STRING_STR"]"));
        }

        l->i = i;
        l->line += nls;
        G.err_line = l->line;

        RETURN_STATUS(BC_STATUS_SUCCESS);
}
#if ERRORS_ARE_FATAL
# define zdc_lex_string(...) (zdc_lex_string(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zdc_lex_token(BcLex *l)
{
        BcStatus s = BC_STATUS_SUCCESS;
        char c = l->buf[l->i++], c2;
        size_t i;

        for (i = 0; i < ARRAY_SIZE(dc_lex_regs); ++i) {
                if (l->t.last == dc_lex_regs[i])
                        RETURN_STATUS(zdc_lex_register(l));
        }

        if (c >= '%' && c <= '~'
         && (l->t.t = dc_lex_tokens[(c - '%')]) != BC_LEX_INVALID
        ) {
                RETURN_STATUS(s);
        }

        // This is the workhorse of the lexer.
        switch (c) {
                case '\0':
                        l->t.t = BC_LEX_EOF;
                        break;
                case '\n':
                case '\t':
                case '\v':
                case '\f':
                case '\r':
                case ' ':
                        l->newline = (c == '\n');
                        bc_lex_whitespace(l);
                        break;
                case '!':
                        c2 = l->buf[l->i];
                        if (c2 == '=')
                                l->t.t = BC_LEX_OP_REL_NE;
                        else if (c2 == '<')
                                l->t.t = BC_LEX_OP_REL_LE;
                        else if (c2 == '>')
                                l->t.t = BC_LEX_OP_REL_GE;
                        else
                                RETURN_STATUS(bc_error_bad_character(c));
                        ++l->i;
                        break;
                case '#':
                        bc_lex_lineComment(l);
                        break;
                case '.':
                        if (isdigit(l->buf[l->i]))
                                s = zbc_lex_number(l, c);
                        else
                                s = bc_error_bad_character(c);
                        break;
                case '0':
                case '1':
                case '2':
                case '3':
                case '4':
                case '5':
                case '6':
                case '7':
                case '8':
                case '9':
                case 'A':
                case 'B':
                case 'C':
                case 'D':
                case 'E':
                case 'F':
                        s = zbc_lex_number(l, c);
                        break;
                case '[':
                        s = zdc_lex_string(l);
                        break;
                default:
                        l->t.t = BC_LEX_INVALID;
                        s = bc_error_bad_character(c);
                        break;
        }

        RETURN_STATUS(s);
}
#endif // ENABLE_DC

static void bc_program_addFunc(char *name, size_t *idx);

static void bc_parse_addFunc(BcParse *p, char *name, size_t *idx)
{
        bc_program_addFunc(name, idx);
        p->func = bc_program_func(p->fidx);
}

#define bc_parse_push(p, i) bc_vec_pushByte(&(p)->func->code, (char) (i))

static void bc_parse_pushName(BcParse *p, char *name)
{
        size_t i = 0, len = strlen(name);

        for (; i < len; ++i) bc_parse_push(p, name[i]);
        bc_parse_push(p, BC_PARSE_STREND);

        free(name);
}

static void bc_parse_pushIndex(BcParse *p, size_t idx)
{
        size_t mask;
        unsigned amt;

        mask = ((size_t)0xff) << (sizeof(idx) * 8 - 8);
        amt = sizeof(idx);
        do {
                if (idx & mask) break;
                mask >>= 8;
                amt--;
        } while (amt != 0);

        bc_parse_push(p, amt);

        while (idx != 0) {
                bc_parse_push(p, (unsigned char)idx);
                idx >>= 8;
        }
}

static void bc_parse_number(BcParse *p, BcInst *prev, size_t *nexs)
{
        char *num = xstrdup(p->l.t.v.v);
        size_t idx = G.prog.consts.len;

        bc_vec_push(&G.prog.consts, &num);

        bc_parse_push(p, BC_INST_NUM);
        bc_parse_pushIndex(p, idx);

        ++(*nexs);
        (*prev) = BC_INST_NUM;
}

static BC_STATUS zbc_parse_parse(BcParse *p);
static BC_STATUS zdc_parse_parse(BcParse *p);

static BC_STATUS zcommon_parse(BcParse *p)
{
        if (IS_BC) {
                IF_BC(RETURN_STATUS(zbc_parse_parse(p));)
        }
        IF_DC(RETURN_STATUS(zdc_parse_parse(p));)
}

static BC_STATUS zbc_parse_text(BcParse *p, const char *text)
{
        BcStatus s;

        p->func = bc_program_func(p->fidx);

        if (!text[0] && !BC_PARSE_CAN_EXEC(p)) {
                p->l.t.t = BC_LEX_INVALID;
                s = BC_STATUS_SUCCESS;
                ERROR_RETURN(s =) zcommon_parse(p);
                if (s) RETURN_STATUS(s);
                if (!BC_PARSE_CAN_EXEC(p))
                        RETURN_STATUS(bc_error("file is not executable"));
        }

        RETURN_STATUS(zbc_lex_text(&p->l, text));
}
#if ERRORS_ARE_FATAL
# define zbc_parse_text(...) (zbc_parse_text(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

// Called when parsing or execution detects a failure,
// resets execution structures.
static void bc_program_reset(void)
{
        BcFunc *f;
        BcInstPtr *ip;

        bc_vec_npop(&G.prog.stack, G.prog.stack.len - 1);
        bc_vec_pop_all(&G.prog.results);

        f = bc_program_func(0);
        ip = bc_vec_top(&G.prog.stack);
        ip->idx = f->code.len;
}

#define bc_parse_updateFunc(p, f) \
        ((p)->func = bc_program_func((p)->fidx = (f)))

// Called when zbc/zdc_parse_parse() detects a failure,
// resets parsing structures.
static void bc_parse_reset(BcParse *p)
{
        if (p->fidx != BC_PROG_MAIN) {
                p->func->nparams = 0;
                bc_vec_pop_all(&p->func->code);
                bc_vec_pop_all(&p->func->autos);
                bc_vec_pop_all(&p->func->labels);

                bc_parse_updateFunc(p, BC_PROG_MAIN);
        }

        p->l.i = p->l.len;
        p->l.t.t = BC_LEX_EOF;
        p->auto_part = (p->nbraces = 0);

        bc_vec_npop(&p->flags, p->flags.len - 1);
        bc_vec_pop_all(&p->exits);
        bc_vec_pop_all(&p->conds);
        bc_vec_pop_all(&p->ops);

        bc_program_reset();
}

static void bc_parse_free(BcParse *p)
{
        bc_vec_free(&p->flags);
        bc_vec_free(&p->exits);
        bc_vec_free(&p->conds);
        bc_vec_free(&p->ops);
        bc_lex_free(&p->l);
}

static void bc_parse_create(BcParse *p, size_t func)
{
        memset(p, 0, sizeof(BcParse));

        bc_lex_init(&p->l);
        bc_vec_init(&p->flags, sizeof(uint8_t), NULL);
        bc_vec_init(&p->exits, sizeof(BcInstPtr), NULL);
        bc_vec_init(&p->conds, sizeof(size_t), NULL);
        bc_vec_pushZeroByte(&p->flags);
        bc_vec_init(&p->ops, sizeof(BcLexType), NULL);

        // p->auto_part = p->nbraces = 0; - already is
        bc_parse_updateFunc(p, func);
}

#if ENABLE_BC

#define BC_PARSE_TOP_OP(p) (*((BcLexType *) bc_vec_top(&(p)->ops)))
#define BC_PARSE_LEAF(p, rparen)                                \
        (((p) >= BC_INST_NUM && (p) <= BC_INST_SQRT) || (rparen) || \
         (p) == BC_INST_INC_POST || (p) == BC_INST_DEC_POST)

// We can calculate the conversion between tokens and exprs by subtracting the
// position of the first operator in the lex enum and adding the position of the
// first in the expr enum. Note: This only works for binary operators.
#define BC_PARSE_TOKEN_INST(t) ((char) ((t) -BC_LEX_NEG + BC_INST_NEG))

static BC_STATUS zbc_parse_else(BcParse *p);
static BC_STATUS zbc_parse_stmt(BcParse *p);
static BC_STATUS zbc_parse_expr(BcParse *p, uint8_t flags, BcParseNext next);
static BcStatus bc_parse_expr_empty_ok(BcParse *p, uint8_t flags, BcParseNext next);
#if ERRORS_ARE_FATAL
# define zbc_parse_else(...) (zbc_parse_else(__VA_ARGS__), BC_STATUS_SUCCESS)
# define zbc_parse_stmt(...) (zbc_parse_stmt(__VA_ARGS__), BC_STATUS_SUCCESS)
# define zbc_parse_expr(...) (zbc_parse_expr(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_parse_operator(BcParse *p, BcLexType type, size_t start,
                                  size_t *nexprs, bool next)
{
        BcStatus s = BC_STATUS_SUCCESS;
        BcLexType t;
        char l, r = bc_parse_op_PREC(type - BC_LEX_OP_INC);
        bool left = bc_parse_op_LEFT(type - BC_LEX_OP_INC);

        while (p->ops.len > start) {

                t = BC_PARSE_TOP_OP(p);
                if (t == BC_LEX_LPAREN) break;

                l = bc_parse_op_PREC(t - BC_LEX_OP_INC);
                if (l >= r && (l != r || !left)) break;

                bc_parse_push(p, BC_PARSE_TOKEN_INST(t));
                bc_vec_pop(&p->ops);
                *nexprs -= t != BC_LEX_OP_BOOL_NOT && t != BC_LEX_NEG;
        }

        bc_vec_push(&p->ops, &type);
        if (next) s = zbc_lex_next(&p->l);

        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_parse_operator(...) (zbc_parse_operator(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_parse_rightParen(BcParse *p, size_t ops_bgn, size_t *nexs)
{
        BcLexType top;

        if (p->ops.len <= ops_bgn)
                RETURN_STATUS(bc_error_bad_expression());
        top = BC_PARSE_TOP_OP(p);

        while (top != BC_LEX_LPAREN) {
                bc_parse_push(p, BC_PARSE_TOKEN_INST(top));

                bc_vec_pop(&p->ops);
                *nexs -= top != BC_LEX_OP_BOOL_NOT && top != BC_LEX_NEG;

                if (p->ops.len <= ops_bgn)
                        RETURN_STATUS(bc_error_bad_expression());
                top = BC_PARSE_TOP_OP(p);
        }

        bc_vec_pop(&p->ops);

        RETURN_STATUS(zbc_lex_next(&p->l));
}
#if ERRORS_ARE_FATAL
# define zbc_parse_rightParen(...) (zbc_parse_rightParen(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_parse_params(BcParse *p, uint8_t flags)
{
        BcStatus s;
        bool comma = false;
        size_t nparams;

        s = zbc_lex_next(&p->l);
        if (s) RETURN_STATUS(s);

        for (nparams = 0; p->l.t.t != BC_LEX_RPAREN; ++nparams) {
                flags = (flags & ~(BC_PARSE_PRINT | BC_PARSE_REL)) | BC_PARSE_ARRAY;
                s = zbc_parse_expr(p, flags, bc_parse_next_param);
                if (s) RETURN_STATUS(s);

                comma = p->l.t.t == BC_LEX_COMMA;
                if (comma) {
                        s = zbc_lex_next(&p->l);
                        if (s) RETURN_STATUS(s);
                }
        }

        if (comma) RETURN_STATUS(bc_error_bad_token());
        bc_parse_push(p, BC_INST_CALL);
        bc_parse_pushIndex(p, nparams);

        RETURN_STATUS(BC_STATUS_SUCCESS);
}
#if ERRORS_ARE_FATAL
# define zbc_parse_params(...) (zbc_parse_params(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_parse_call(BcParse *p, char *name, uint8_t flags)
{
        BcStatus s;
        BcId entry, *entry_ptr;
        size_t idx;

        entry.name = name;

        s = zbc_parse_params(p, flags);
        if (s) goto err;

        if (p->l.t.t != BC_LEX_RPAREN) {
                s = bc_error_bad_token();
                goto err;
        }

        idx = bc_map_index(&G.prog.fn_map, &entry);

        if (idx == BC_VEC_INVALID_IDX) {
                name = xstrdup(entry.name);
                bc_parse_addFunc(p, name, &idx);
                idx = bc_map_index(&G.prog.fn_map, &entry);
                free(entry.name);
        } else
                free(name);

        entry_ptr = bc_vec_item(&G.prog.fn_map, idx);
        bc_parse_pushIndex(p, entry_ptr->idx);

        RETURN_STATUS(zbc_lex_next(&p->l));

err:
        free(name);
        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_parse_call(...) (zbc_parse_call(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_parse_name(BcParse *p, BcInst *type, uint8_t flags)
{
        BcStatus s;
        char *name;

        name = xstrdup(p->l.t.v.v);
        s = zbc_lex_next(&p->l);
        if (s) goto err;

        if (p->l.t.t == BC_LEX_LBRACKET) {
                s = zbc_lex_next(&p->l);
                if (s) goto err;

                if (p->l.t.t == BC_LEX_RBRACKET) {
                        if (!(flags & BC_PARSE_ARRAY)) {
                                s = bc_error_bad_expression();
                                goto err;
                        }
                        *type = BC_INST_ARRAY;
                } else {
                        *type = BC_INST_ARRAY_ELEM;
                        flags &= ~(BC_PARSE_PRINT | BC_PARSE_REL);
                        s = zbc_parse_expr(p, flags, bc_parse_next_elem);
                        if (s) goto err;
                }
                s = zbc_lex_next(&p->l);
                if (s) goto err;
                bc_parse_push(p, *type);
                bc_parse_pushName(p, name);
        }
        else if (p->l.t.t == BC_LEX_LPAREN) {
                if (flags & BC_PARSE_NOCALL) {
                        s = bc_error_bad_token();
                        goto err;
                }
                *type = BC_INST_CALL;
                s = zbc_parse_call(p, name, flags);
        } else {
                *type = BC_INST_VAR;
                bc_parse_push(p, BC_INST_VAR);
                bc_parse_pushName(p, name);
        }

        RETURN_STATUS(s);

err:
        free(name);
        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_parse_name(...) (zbc_parse_name(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_parse_read(BcParse *p)
{
        BcStatus s;

        s = zbc_lex_next(&p->l);
        if (s) RETURN_STATUS(s);
        if (p->l.t.t != BC_LEX_LPAREN) RETURN_STATUS(bc_error_bad_token());

        s = zbc_lex_next(&p->l);
        if (s) RETURN_STATUS(s);
        if (p->l.t.t != BC_LEX_RPAREN) RETURN_STATUS(bc_error_bad_token());

        bc_parse_push(p, BC_INST_READ);

        RETURN_STATUS(zbc_lex_next(&p->l));
}
#if ERRORS_ARE_FATAL
# define zbc_parse_read(...) (zbc_parse_read(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_parse_builtin(BcParse *p, BcLexType type, uint8_t flags,
                                 BcInst *prev)
{
        BcStatus s;

        s = zbc_lex_next(&p->l);
        if (s) RETURN_STATUS(s);
        if (p->l.t.t != BC_LEX_LPAREN) RETURN_STATUS(bc_error_bad_token());

        flags = (flags & ~(BC_PARSE_PRINT | BC_PARSE_REL)) | BC_PARSE_ARRAY;

        s = zbc_lex_next(&p->l);
        if (s) RETURN_STATUS(s);

        s = zbc_parse_expr(p, flags, bc_parse_next_rel);
        if (s) RETURN_STATUS(s);

        if (p->l.t.t != BC_LEX_RPAREN) RETURN_STATUS(bc_error_bad_token());

        *prev = (type == BC_LEX_KEY_LENGTH) ? BC_INST_LENGTH : BC_INST_SQRT;
        bc_parse_push(p, *prev);

        RETURN_STATUS(zbc_lex_next(&p->l));
}
#if ERRORS_ARE_FATAL
# define zbc_parse_builtin(...) (zbc_parse_builtin(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_parse_scale(BcParse *p, BcInst *type, uint8_t flags)
{
        BcStatus s;

        s = zbc_lex_next(&p->l);
        if (s) RETURN_STATUS(s);

        if (p->l.t.t != BC_LEX_LPAREN) {
                *type = BC_INST_SCALE;
                bc_parse_push(p, BC_INST_SCALE);
                RETURN_STATUS(BC_STATUS_SUCCESS);
        }

        *type = BC_INST_SCALE_FUNC;
        flags &= ~(BC_PARSE_PRINT | BC_PARSE_REL);

        s = zbc_lex_next(&p->l);
        if (s) RETURN_STATUS(s);

        s = zbc_parse_expr(p, flags, bc_parse_next_rel);
        if (s) RETURN_STATUS(s);
        if (p->l.t.t != BC_LEX_RPAREN)
                RETURN_STATUS(bc_error_bad_token());
        bc_parse_push(p, BC_INST_SCALE_FUNC);

        RETURN_STATUS(zbc_lex_next(&p->l));
}
#if ERRORS_ARE_FATAL
# define zbc_parse_scale(...) (zbc_parse_scale(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_parse_incdec(BcParse *p, BcInst *prev, bool *paren_expr,
                                size_t *nexprs, uint8_t flags)
{
        BcStatus s;
        BcLexType type;
        char inst;
        BcInst etype = *prev;

        if (etype == BC_INST_VAR || etype == BC_INST_ARRAY_ELEM ||
            etype == BC_INST_SCALE || etype == BC_INST_LAST ||
            etype == BC_INST_IBASE || etype == BC_INST_OBASE)
        {
                *prev = inst = BC_INST_INC_POST + (p->l.t.t != BC_LEX_OP_INC);
                bc_parse_push(p, inst);
                s = zbc_lex_next(&p->l);
        }
        else {
                *prev = inst = BC_INST_INC_PRE + (p->l.t.t != BC_LEX_OP_INC);
                *paren_expr = true;

                s = zbc_lex_next(&p->l);
                if (s) RETURN_STATUS(s);
                type = p->l.t.t;

                // Because we parse the next part of the expression
                // right here, we need to increment this.
                *nexprs = *nexprs + 1;

                switch (type) {
                        case BC_LEX_NAME:
                                s = zbc_parse_name(p, prev, flags | BC_PARSE_NOCALL);
                                break;
                        case BC_LEX_KEY_IBASE:
                        case BC_LEX_KEY_LAST:
                        case BC_LEX_KEY_OBASE:
                                bc_parse_push(p, type - BC_LEX_KEY_IBASE + BC_INST_IBASE);
                                s = zbc_lex_next(&p->l);
                                break;
                        case BC_LEX_KEY_SCALE:
                                s = zbc_lex_next(&p->l);
                                if (s) RETURN_STATUS(s);
                                if (p->l.t.t == BC_LEX_LPAREN)
                                        s = bc_error_bad_token();
                                else
                                        bc_parse_push(p, BC_INST_SCALE);
                                break;
                        default:
                                s = bc_error_bad_token();
                                break;
                }

                if (!s) bc_parse_push(p, inst);
        }

        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_parse_incdec(...) (zbc_parse_incdec(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_parse_minus(BcParse *p, BcInst *prev, size_t ops_bgn,
                               bool rparen, size_t *nexprs)
{
        BcStatus s;
        BcLexType type;
        BcInst etype = *prev;

        s = zbc_lex_next(&p->l);
        if (s) RETURN_STATUS(s);

        type = rparen || etype == BC_INST_INC_POST || etype == BC_INST_DEC_POST ||
                       (etype >= BC_INST_NUM && etype <= BC_INST_SQRT) ?
                   BC_LEX_OP_MINUS :
                   BC_LEX_NEG;
        *prev = BC_PARSE_TOKEN_INST(type);

        // We can just push onto the op stack because this is the largest
        // precedence operator that gets pushed. Inc/dec does not.
        if (type != BC_LEX_OP_MINUS)
                bc_vec_push(&p->ops, &type);
        else
                s = zbc_parse_operator(p, type, ops_bgn, nexprs, false);

        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_parse_minus(...) (zbc_parse_minus(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_parse_string(BcParse *p, char inst)
{
        char *str = xstrdup(p->l.t.v.v);

        bc_parse_push(p, BC_INST_STR);
        bc_parse_pushIndex(p, G.prog.strs.len);
        bc_vec_push(&G.prog.strs, &str);
        bc_parse_push(p, inst);

        RETURN_STATUS(zbc_lex_next(&p->l));
}
#if ERRORS_ARE_FATAL
# define zbc_parse_string(...) (zbc_parse_string(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_parse_print(BcParse *p)
{
        BcStatus s;
        BcLexType type;
        bool comma;

        s = zbc_lex_next(&p->l);
        if (s) RETURN_STATUS(s);

        type = p->l.t.t;

        if (type == BC_LEX_SCOLON || type == BC_LEX_NLINE)
                RETURN_STATUS(bc_error("bad print statement"));

        comma = false;
        while (type != BC_LEX_SCOLON && type != BC_LEX_NLINE) {
                if (type == BC_LEX_STR) {
                        s = zbc_parse_string(p, BC_INST_PRINT_POP);
                        if (s) RETURN_STATUS(s);
                } else {
                        s = zbc_parse_expr(p, 0, bc_parse_next_print);
                        if (s) RETURN_STATUS(s);
                        bc_parse_push(p, BC_INST_PRINT_POP);
                }

                comma = p->l.t.t == BC_LEX_COMMA;
                if (comma) {
                        s = zbc_lex_next(&p->l);
                        if (s) RETURN_STATUS(s);
                }
                type = p->l.t.t;
        }

        if (comma) RETURN_STATUS(bc_error_bad_token());

        RETURN_STATUS(zbc_lex_next(&p->l));
}
#if ERRORS_ARE_FATAL
# define zbc_parse_print(...) (zbc_parse_print(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_parse_return(BcParse *p)
{
        BcStatus s;
        BcLexType t;
        bool paren;

        if (!BC_PARSE_FUNC(p)) RETURN_STATUS(bc_error_bad_token());

        s = zbc_lex_next(&p->l);
        if (s) RETURN_STATUS(s);

        t = p->l.t.t;
        paren = t == BC_LEX_LPAREN;

        if (t == BC_LEX_NLINE || t == BC_LEX_SCOLON)
                bc_parse_push(p, BC_INST_RET0);
        else {
                s = bc_parse_expr_empty_ok(p, 0, bc_parse_next_expr);
                if (s == BC_STATUS_PARSE_EMPTY_EXP) {
                        bc_parse_push(p, BC_INST_RET0);
                        s = zbc_lex_next(&p->l);
                }
                if (s) RETURN_STATUS(s);

                if (!paren || p->l.t.last != BC_LEX_RPAREN) {
                        s = bc_POSIX_requires("parentheses around return expressions");
                        ERROR_RETURN(if (s) RETURN_STATUS(s);)
                }

                bc_parse_push(p, BC_INST_RET);
        }

        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_parse_return(...) (zbc_parse_return(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_parse_endBody(BcParse *p, bool brace)
{
        BcStatus s = BC_STATUS_SUCCESS;

        if (p->flags.len <= 1 || (brace && p->nbraces == 0))
                RETURN_STATUS(bc_error_bad_token());

        if (brace) {
                if (p->l.t.t != BC_LEX_RBRACE)
                        RETURN_STATUS(bc_error_bad_token());
                if (!p->nbraces)
                        RETURN_STATUS(bc_error_bad_token());
                --p->nbraces;
                s = zbc_lex_next(&p->l);
                if (s) RETURN_STATUS(s);
        }

        if (BC_PARSE_IF(p)) {
                uint8_t *flag_ptr;

                while (p->l.t.t == BC_LEX_NLINE) {
                        s = zbc_lex_next(&p->l);
                        if (s) RETURN_STATUS(s);
                }

                bc_vec_pop(&p->flags);

                flag_ptr = BC_PARSE_TOP_FLAG_PTR(p);
                *flag_ptr = (*flag_ptr | BC_PARSE_FLAG_IF_END);

                if (p->l.t.t == BC_LEX_KEY_ELSE)
                        s = zbc_parse_else(p);
        }
        else if (BC_PARSE_ELSE(p)) {
                BcInstPtr *ip;
                size_t *label;

                bc_vec_pop(&p->flags);

                ip = bc_vec_top(&p->exits);
                label = bc_vec_item(&p->func->labels, ip->idx);
                *label = p->func->code.len;

                bc_vec_pop(&p->exits);
        }
        else if (BC_PARSE_FUNC_INNER(p)) {
                bc_parse_push(p, BC_INST_RET0);
                bc_parse_updateFunc(p, BC_PROG_MAIN);
                bc_vec_pop(&p->flags);
        }
        else {
                BcInstPtr *ip = bc_vec_top(&p->exits);
                size_t *label = bc_vec_top(&p->conds);

                bc_parse_push(p, BC_INST_JUMP);
                bc_parse_pushIndex(p, *label);

                label = bc_vec_item(&p->func->labels, ip->idx);
                *label = p->func->code.len;

                bc_vec_pop(&p->flags);
                bc_vec_pop(&p->exits);
                bc_vec_pop(&p->conds);
        }

        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_parse_endBody(...) (zbc_parse_endBody(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static void bc_parse_startBody(BcParse *p, uint8_t flags)
{
        uint8_t *flag_ptr = BC_PARSE_TOP_FLAG_PTR(p);
        flags |= (*flag_ptr & (BC_PARSE_FLAG_FUNC | BC_PARSE_FLAG_LOOP));
        flags |= BC_PARSE_FLAG_BODY;
        bc_vec_push(&p->flags, &flags);
}

static void bc_parse_noElse(BcParse *p)
{
        BcInstPtr *ip;
        size_t *label;
        uint8_t *flag_ptr = BC_PARSE_TOP_FLAG_PTR(p);

        *flag_ptr = (*flag_ptr & ~(BC_PARSE_FLAG_IF_END));

        ip = bc_vec_top(&p->exits);
        label = bc_vec_item(&p->func->labels, ip->idx);
        *label = p->func->code.len;

        bc_vec_pop(&p->exits);
}

static BC_STATUS zbc_parse_if(BcParse *p)
{
        BcStatus s;
        BcInstPtr ip;

        s = zbc_lex_next(&p->l);
        if (s) RETURN_STATUS(s);
        if (p->l.t.t != BC_LEX_LPAREN) RETURN_STATUS(bc_error_bad_token());

        s = zbc_lex_next(&p->l);
        if (s) RETURN_STATUS(s);
        s = zbc_parse_expr(p, BC_PARSE_REL, bc_parse_next_rel);
        if (s) RETURN_STATUS(s);
        if (p->l.t.t != BC_LEX_RPAREN) RETURN_STATUS(bc_error_bad_token());

        s = zbc_lex_next(&p->l);
        if (s) RETURN_STATUS(s);
        bc_parse_push(p, BC_INST_JUMP_ZERO);

        ip.idx = p->func->labels.len;
        ip.func = ip.len = 0;

        bc_parse_pushIndex(p, ip.idx);
        bc_vec_push(&p->exits, &ip);
        bc_vec_push(&p->func->labels, &ip.idx);
        bc_parse_startBody(p, BC_PARSE_FLAG_IF);

        RETURN_STATUS(BC_STATUS_SUCCESS);
}
#if ERRORS_ARE_FATAL
# define zbc_parse_if(...) (zbc_parse_if(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

#undef zbc_parse_else
static BC_STATUS zbc_parse_else(BcParse *p)
{
        BcInstPtr ip;

        if (!BC_PARSE_IF_END(p)) RETURN_STATUS(bc_error_bad_token());

        ip.idx = p->func->labels.len;
        ip.func = ip.len = 0;

        bc_parse_push(p, BC_INST_JUMP);
        bc_parse_pushIndex(p, ip.idx);

        bc_parse_noElse(p);

        bc_vec_push(&p->exits, &ip);
        bc_vec_push(&p->func->labels, &ip.idx);
        bc_parse_startBody(p, BC_PARSE_FLAG_ELSE);

        RETURN_STATUS(zbc_lex_next(&p->l));
}
#if ERRORS_ARE_FATAL
# define zbc_parse_else(...) (zbc_parse_else(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_parse_while(BcParse *p)
{
        BcStatus s;
        BcInstPtr ip;

        s = zbc_lex_next(&p->l);
        if (s) RETURN_STATUS(s);
        if (p->l.t.t != BC_LEX_LPAREN) RETURN_STATUS(bc_error_bad_token());
        s = zbc_lex_next(&p->l);
        if (s) RETURN_STATUS(s);

        ip.idx = p->func->labels.len;

        bc_vec_push(&p->func->labels, &p->func->code.len);
        bc_vec_push(&p->conds, &ip.idx);

        ip.idx = p->func->labels.len;
        ip.func = 1;
        ip.len = 0;

        bc_vec_push(&p->exits, &ip);
        bc_vec_push(&p->func->labels, &ip.idx);

        s = zbc_parse_expr(p, BC_PARSE_REL, bc_parse_next_rel);
        if (s) RETURN_STATUS(s);
        if (p->l.t.t != BC_LEX_RPAREN) RETURN_STATUS(bc_error_bad_token());
        s = zbc_lex_next(&p->l);
        if (s) RETURN_STATUS(s);

        bc_parse_push(p, BC_INST_JUMP_ZERO);
        bc_parse_pushIndex(p, ip.idx);
        bc_parse_startBody(p, BC_PARSE_FLAG_LOOP | BC_PARSE_FLAG_LOOP_INNER);

        RETURN_STATUS(BC_STATUS_SUCCESS);
}
#if ERRORS_ARE_FATAL
# define zbc_parse_while(...) (zbc_parse_while(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_parse_for(BcParse *p)
{
        BcStatus s;
        BcInstPtr ip;
        size_t cond_idx, exit_idx, body_idx, update_idx;

        s = zbc_lex_next(&p->l);
        if (s) RETURN_STATUS(s);
        if (p->l.t.t != BC_LEX_LPAREN) RETURN_STATUS(bc_error_bad_token());
        s = zbc_lex_next(&p->l);
        if (s) RETURN_STATUS(s);

        if (p->l.t.t != BC_LEX_SCOLON)
                s = zbc_parse_expr(p, 0, bc_parse_next_for);
        else
                s = bc_POSIX_does_not_allow_empty_X_expression_in_for("init");

        if (s) RETURN_STATUS(s);
        if (p->l.t.t != BC_LEX_SCOLON) RETURN_STATUS(bc_error_bad_token());
        s = zbc_lex_next(&p->l);
        if (s) RETURN_STATUS(s);

        cond_idx = p->func->labels.len;
        update_idx = cond_idx + 1;
        body_idx = update_idx + 1;
        exit_idx = body_idx + 1;

        bc_vec_push(&p->func->labels, &p->func->code.len);

        if (p->l.t.t != BC_LEX_SCOLON)
                s = zbc_parse_expr(p, BC_PARSE_REL, bc_parse_next_for);
        else
                s = bc_POSIX_does_not_allow_empty_X_expression_in_for("condition");

        if (s) RETURN_STATUS(s);
        if (p->l.t.t != BC_LEX_SCOLON) RETURN_STATUS(bc_error_bad_token());

        s = zbc_lex_next(&p->l);
        if (s) RETURN_STATUS(s);

        bc_parse_push(p, BC_INST_JUMP_ZERO);
        bc_parse_pushIndex(p, exit_idx);
        bc_parse_push(p, BC_INST_JUMP);
        bc_parse_pushIndex(p, body_idx);

        ip.idx = p->func->labels.len;

        bc_vec_push(&p->conds, &update_idx);
        bc_vec_push(&p->func->labels, &p->func->code.len);

        if (p->l.t.t != BC_LEX_RPAREN)
                s = zbc_parse_expr(p, 0, bc_parse_next_rel);
        else
                s = bc_POSIX_does_not_allow_empty_X_expression_in_for("update");

        if (s) RETURN_STATUS(s);

        if (p->l.t.t != BC_LEX_RPAREN) RETURN_STATUS(bc_error_bad_token());
        bc_parse_push(p, BC_INST_JUMP);
        bc_parse_pushIndex(p, cond_idx);
        bc_vec_push(&p->func->labels, &p->func->code.len);

        ip.idx = exit_idx;
        ip.func = 1;
        ip.len = 0;

        bc_vec_push(&p->exits, &ip);
        bc_vec_push(&p->func->labels, &ip.idx);
        s = zbc_lex_next(&p->l);
        if (s) RETURN_STATUS(s);
        bc_parse_startBody(p, BC_PARSE_FLAG_LOOP | BC_PARSE_FLAG_LOOP_INNER);

        RETURN_STATUS(BC_STATUS_SUCCESS);
}
#if ERRORS_ARE_FATAL
# define zbc_parse_for(...) (zbc_parse_for(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_parse_loopExit(BcParse *p, BcLexType type)
{
        BcStatus s;
        size_t i;
        BcInstPtr *ip;

        if (!BC_PARSE_LOOP(p)) RETURN_STATUS(bc_error_bad_token());

        if (type == BC_LEX_KEY_BREAK) {
                if (p->exits.len == 0) RETURN_STATUS(bc_error_bad_token());

                i = p->exits.len - 1;
                ip = bc_vec_item(&p->exits, i);

                while (!ip->func && i < p->exits.len)
                        ip = bc_vec_item(&p->exits, i--);
                if (i >= p->exits.len && !ip->func)
                        RETURN_STATUS(bc_error_bad_token());

                i = ip->idx;
        }
        else
                i = *((size_t *) bc_vec_top(&p->conds));

        bc_parse_push(p, BC_INST_JUMP);
        bc_parse_pushIndex(p, i);

        s = zbc_lex_next(&p->l);
        if (s) RETURN_STATUS(s);

        if (p->l.t.t != BC_LEX_SCOLON && p->l.t.t != BC_LEX_NLINE)
                RETURN_STATUS(bc_error_bad_token());

        RETURN_STATUS(zbc_lex_next(&p->l));
}
#if ERRORS_ARE_FATAL
# define zbc_parse_loopExit(...) (zbc_parse_loopExit(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_parse_func(BcParse *p)
{
        BcStatus s;
        bool var, comma = false;
        uint8_t flags;
        char *name;

        s = zbc_lex_next(&p->l);
        if (s) RETURN_STATUS(s);
        if (p->l.t.t != BC_LEX_NAME)
                RETURN_STATUS(bc_error("bad function definition"));

        name = xstrdup(p->l.t.v.v);
        bc_parse_addFunc(p, name, &p->fidx);

        s = zbc_lex_next(&p->l);
        if (s) RETURN_STATUS(s);
        if (p->l.t.t != BC_LEX_LPAREN)
                RETURN_STATUS(bc_error("bad function definition"));
        s = zbc_lex_next(&p->l);
        if (s) RETURN_STATUS(s);

        while (p->l.t.t != BC_LEX_RPAREN) {
                if (p->l.t.t != BC_LEX_NAME)
                        RETURN_STATUS(bc_error("bad function definition"));

                ++p->func->nparams;

                name = xstrdup(p->l.t.v.v);
                s = zbc_lex_next(&p->l);
                if (s) goto err;

                var = p->l.t.t != BC_LEX_LBRACKET;

                if (!var) {
                        s = zbc_lex_next(&p->l);
                        if (s) goto err;

                        if (p->l.t.t != BC_LEX_RBRACKET) {
                                s = bc_error("bad function definition");
                                goto err;
                        }

                        s = zbc_lex_next(&p->l);
                        if (s) goto err;
                }

                comma = p->l.t.t == BC_LEX_COMMA;
                if (comma) {
                        s = zbc_lex_next(&p->l);
                        if (s) goto err;
                }

                s = zbc_func_insert(p->func, name, var);
                if (s) goto err;
        }

        if (comma) RETURN_STATUS(bc_error("bad function definition"));

        flags = BC_PARSE_FLAG_FUNC | BC_PARSE_FLAG_FUNC_INNER | BC_PARSE_FLAG_BODY;
        bc_parse_startBody(p, flags);

        s = zbc_lex_next(&p->l);
        if (s) RETURN_STATUS(s);

        if (p->l.t.t != BC_LEX_LBRACE)
                s = bc_POSIX_requires("the left brace be on the same line as the function header");

        RETURN_STATUS(s);

err:
        free(name);
        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_parse_func(...) (zbc_parse_func(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_parse_auto(BcParse *p)
{
        BcStatus s;
        bool comma, var, one;
        char *name;

        if (!p->auto_part) RETURN_STATUS(bc_error_bad_token());

        s = zbc_lex_next(&p->l);
        if (s) RETURN_STATUS(s);

        p->auto_part = comma = false;
        one = p->l.t.t == BC_LEX_NAME;

        while (p->l.t.t == BC_LEX_NAME) {
                name = xstrdup(p->l.t.v.v);
                s = zbc_lex_next(&p->l);
                if (s) goto err;

                var = p->l.t.t != BC_LEX_LBRACKET;
                if (!var) {
                        s = zbc_lex_next(&p->l);
                        if (s) goto err;

                        if (p->l.t.t != BC_LEX_RBRACKET) {
                                s = bc_error("bad function definition");
                                goto err;
                        }

                        s = zbc_lex_next(&p->l);
                        if (s) goto err;
                }

                comma = p->l.t.t == BC_LEX_COMMA;
                if (comma) {
                        s = zbc_lex_next(&p->l);
                        if (s) goto err;
                }

                s = zbc_func_insert(p->func, name, var);
                if (s) goto err;
        }

        if (comma) RETURN_STATUS(bc_error("bad function definition"));
        if (!one) RETURN_STATUS(bc_error("no auto variable found"));

        if (p->l.t.t != BC_LEX_NLINE && p->l.t.t != BC_LEX_SCOLON)
                RETURN_STATUS(bc_error_bad_token());

        RETURN_STATUS(zbc_lex_next(&p->l));

err:
        free(name);
        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_parse_auto(...) (zbc_parse_auto(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_parse_body(BcParse *p, bool brace)
{
        BcStatus s = BC_STATUS_SUCCESS;
        uint8_t *flag_ptr = bc_vec_top(&p->flags);

        *flag_ptr &= ~(BC_PARSE_FLAG_BODY);

        if (*flag_ptr & BC_PARSE_FLAG_FUNC_INNER) {
                if (!brace) RETURN_STATUS(bc_error_bad_token());

                p->auto_part = p->l.t.t != BC_LEX_KEY_AUTO;

                if (!p->auto_part) {
                        s = zbc_parse_auto(p);
                        if (s) RETURN_STATUS(s);
                }

                if (p->l.t.t == BC_LEX_NLINE) s = zbc_lex_next(&p->l);
        }
        else {
                s = zbc_parse_stmt(p);
                if (!s && !brace) s = zbc_parse_endBody(p, false);
        }

        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_parse_body(...) (zbc_parse_body(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

#undef zbc_parse_stmt
static BC_STATUS zbc_parse_stmt(BcParse *p)
{
        BcStatus s = BC_STATUS_SUCCESS;

        switch (p->l.t.t) {
                case BC_LEX_NLINE:
                        RETURN_STATUS(zbc_lex_next(&p->l));

                case BC_LEX_KEY_ELSE:
                        p->auto_part = false;
                        break;

                case BC_LEX_LBRACE:
                        if (!BC_PARSE_BODY(p)) RETURN_STATUS(bc_error_bad_token());
                        ++p->nbraces;
                        s = zbc_lex_next(&p->l);
                        if (s) RETURN_STATUS(s);
                        RETURN_STATUS(zbc_parse_body(p, true));

                case BC_LEX_KEY_AUTO:
                        RETURN_STATUS(zbc_parse_auto(p));

                default:
                        p->auto_part = false;
                        if (BC_PARSE_IF_END(p)) {
                                bc_parse_noElse(p);
                                RETURN_STATUS(BC_STATUS_SUCCESS);
                        }
                        if (BC_PARSE_BODY(p))
                                RETURN_STATUS(zbc_parse_body(p, false));
                        break;
        }

        switch (p->l.t.t) {
                case BC_LEX_OP_INC:
                case BC_LEX_OP_DEC:
                case BC_LEX_OP_MINUS:
                case BC_LEX_OP_BOOL_NOT:
                case BC_LEX_LPAREN:
                case BC_LEX_NAME:
                case BC_LEX_NUMBER:
                case BC_LEX_KEY_IBASE:
                case BC_LEX_KEY_LAST:
                case BC_LEX_KEY_LENGTH:
                case BC_LEX_KEY_OBASE:
                case BC_LEX_KEY_READ:
                case BC_LEX_KEY_SCALE:
                case BC_LEX_KEY_SQRT:
                        s = zbc_parse_expr(p, BC_PARSE_PRINT, bc_parse_next_expr);
                        break;
                case BC_LEX_KEY_ELSE:
                        s = zbc_parse_else(p);
                        break;
                case BC_LEX_SCOLON:
                        while (!s && p->l.t.t == BC_LEX_SCOLON) s = zbc_lex_next(&p->l);
                        break;
                case BC_LEX_RBRACE:
                        s = zbc_parse_endBody(p, true);
                        break;
                case BC_LEX_STR:
                        s = zbc_parse_string(p, BC_INST_PRINT_STR);
                        break;
                case BC_LEX_KEY_BREAK:
                case BC_LEX_KEY_CONTINUE:
                        s = zbc_parse_loopExit(p, p->l.t.t);
                        break;
                case BC_LEX_KEY_FOR:
                        s = zbc_parse_for(p);
                        break;
                case BC_LEX_KEY_HALT:
                        bc_parse_push(p, BC_INST_HALT);
                        s = zbc_lex_next(&p->l);
                        break;
                case BC_LEX_KEY_IF:
                        s = zbc_parse_if(p);
                        break;
                case BC_LEX_KEY_LIMITS:
                        // "limits" is a compile-time command,
                        // the output is produced at _parse time_.
                        s = zbc_lex_next(&p->l);
                        if (s) RETURN_STATUS(s);
                        printf(
                                "BC_BASE_MAX     = "BC_MAX_OBASE_STR "\n"
                                "BC_DIM_MAX      = "BC_MAX_DIM_STR   "\n"
                                "BC_SCALE_MAX    = "BC_MAX_SCALE_STR "\n"
                                "BC_STRING_MAX   = "BC_MAX_STRING_STR"\n"
                                "BC_NAME_MAX     = "BC_MAX_NAME_STR  "\n"
                                "BC_NUM_MAX      = "BC_MAX_NUM_STR   "\n"
                                "MAX Exponent    = "BC_MAX_EXP_STR   "\n"
                                "Number of vars  = "BC_MAX_VARS_STR  "\n"
                        );
                        break;
                case BC_LEX_KEY_PRINT:
                        s = zbc_parse_print(p);
                        break;
                case BC_LEX_KEY_QUIT:
                        // "quit" is a compile-time command. For example,
                        // "if (0 == 1) quit" terminates when parsing the statement,
                        // not when it is executed
                        QUIT_OR_RETURN_TO_MAIN;
                case BC_LEX_KEY_RETURN:
                        s = zbc_parse_return(p);
                        break;
                case BC_LEX_KEY_WHILE:
                        s = zbc_parse_while(p);
                        break;
                default:
                        s = bc_error_bad_token();
                        break;
        }

        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_parse_stmt(...) (zbc_parse_stmt(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_parse_parse(BcParse *p)
{
        BcStatus s;

        if (p->l.t.t == BC_LEX_EOF)
                s = p->flags.len > 0 ? bc_error("block end could not be found") : bc_error("end of file");
        else if (p->l.t.t == BC_LEX_KEY_DEFINE) {
                if (!BC_PARSE_CAN_EXEC(p))
                        RETURN_STATUS(bc_error_bad_token());
                s = zbc_parse_func(p);
        } else
                s = zbc_parse_stmt(p);

        if (s || G_interrupt) {
                bc_parse_reset(p);
                s = BC_STATUS_FAILURE;
        }

        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_parse_parse(...) (zbc_parse_parse(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

// This is not a "z" function: can also return BC_STATUS_PARSE_EMPTY_EXP
static BcStatus bc_parse_expr_empty_ok(BcParse *p, uint8_t flags, BcParseNext next)
{
        BcStatus s = BC_STATUS_SUCCESS;
        BcInst prev = BC_INST_PRINT;
        BcLexType top, t = p->l.t.t;
        size_t nexprs = 0, ops_bgn = p->ops.len;
        unsigned nparens, nrelops;
        bool paren_first, paren_expr, rprn, done, get_token, assign, bin_last;

        paren_first = p->l.t.t == BC_LEX_LPAREN;
        nparens = nrelops = 0;
        paren_expr = rprn = done = get_token = assign = false;
        bin_last = true;

        for (; !G_interrupt && !s && !done && bc_parse_exprs(t); t = p->l.t.t) {
                switch (t) {

                        case BC_LEX_OP_INC:
                        case BC_LEX_OP_DEC:
                        {
                                s = zbc_parse_incdec(p, &prev, &paren_expr, &nexprs, flags);
                                rprn = get_token = bin_last = false;
                                break;
                        }

                        case BC_LEX_OP_MINUS:
                        {
                                s = zbc_parse_minus(p, &prev, ops_bgn, rprn, &nexprs);
                                rprn = get_token = false;
                                bin_last = prev == BC_INST_MINUS;
                                break;
                        }

                        case BC_LEX_OP_ASSIGN_POWER:
                        case BC_LEX_OP_ASSIGN_MULTIPLY:
                        case BC_LEX_OP_ASSIGN_DIVIDE:
                        case BC_LEX_OP_ASSIGN_MODULUS:
                        case BC_LEX_OP_ASSIGN_PLUS:
                        case BC_LEX_OP_ASSIGN_MINUS:
                        case BC_LEX_OP_ASSIGN:
                        {
                                if (prev != BC_INST_VAR && prev != BC_INST_ARRAY_ELEM &&
                                    prev != BC_INST_SCALE && prev != BC_INST_IBASE &&
                                    prev != BC_INST_OBASE && prev != BC_INST_LAST)
                                {
                                        s = bc_error("bad assignment:"
                                                " left side must be scale,"
                                                " ibase, obase, last, var,"
                                                " or array element"
                                        );
                                        break;
                                }
                        }
                        // Fallthrough.
                        case BC_LEX_OP_POWER:
                        case BC_LEX_OP_MULTIPLY:
                        case BC_LEX_OP_DIVIDE:
                        case BC_LEX_OP_MODULUS:
                        case BC_LEX_OP_PLUS:
                        case BC_LEX_OP_REL_EQ:
                        case BC_LEX_OP_REL_LE:
                        case BC_LEX_OP_REL_GE:
                        case BC_LEX_OP_REL_NE:
                        case BC_LEX_OP_REL_LT:
                        case BC_LEX_OP_REL_GT:
                        case BC_LEX_OP_BOOL_NOT:
                        case BC_LEX_OP_BOOL_OR:
                        case BC_LEX_OP_BOOL_AND:
                        {
                                if (((t == BC_LEX_OP_BOOL_NOT) != bin_last)
                                 || (t != BC_LEX_OP_BOOL_NOT && prev == BC_INST_BOOL_NOT)
                                ) {
                                        return bc_error_bad_expression();
                                }

                                nrelops += t >= BC_LEX_OP_REL_EQ && t <= BC_LEX_OP_REL_GT;
                                prev = BC_PARSE_TOKEN_INST(t);
                                s = zbc_parse_operator(p, t, ops_bgn, &nexprs, true);
                                rprn = get_token = false;
                                bin_last = t != BC_LEX_OP_BOOL_NOT;

                                break;
                        }

                        case BC_LEX_LPAREN:
                        {
                                if (BC_PARSE_LEAF(prev, rprn))
                                        return bc_error_bad_expression();
                                ++nparens;
                                paren_expr = rprn = bin_last = false;
                                get_token = true;
                                bc_vec_push(&p->ops, &t);

                                break;
                        }

                        case BC_LEX_RPAREN:
                        {
                                if (bin_last || prev == BC_INST_BOOL_NOT)
                                        return bc_error_bad_expression();

                                if (nparens == 0) {
                                        s = BC_STATUS_SUCCESS;
                                        done = true;
                                        get_token = false;
                                        break;
                                }
                                else if (!paren_expr)
                                        return BC_STATUS_PARSE_EMPTY_EXP;

                                --nparens;
                                paren_expr = rprn = true;
                                get_token = bin_last = false;

                                s = zbc_parse_rightParen(p, ops_bgn, &nexprs);

                                break;
                        }

                        case BC_LEX_NAME:
                        {
                                if (BC_PARSE_LEAF(prev, rprn))
                                        return bc_error_bad_expression();
                                paren_expr = true;
                                rprn = get_token = bin_last = false;
                                s = zbc_parse_name(p, &prev, flags & ~BC_PARSE_NOCALL);
                                ++nexprs;

                                break;
                        }

                        case BC_LEX_NUMBER:
                        {
                                if (BC_PARSE_LEAF(prev, rprn))
                                        return bc_error_bad_expression();
                                bc_parse_number(p, &prev, &nexprs);
                                paren_expr = get_token = true;
                                rprn = bin_last = false;

                                break;
                        }

                        case BC_LEX_KEY_IBASE:
                        case BC_LEX_KEY_LAST:
                        case BC_LEX_KEY_OBASE:
                        {
                                if (BC_PARSE_LEAF(prev, rprn))
                                        return bc_error_bad_expression();
                                prev = (char) (t - BC_LEX_KEY_IBASE + BC_INST_IBASE);
                                bc_parse_push(p, (char) prev);

                                paren_expr = get_token = true;
                                rprn = bin_last = false;
                                ++nexprs;

                                break;
                        }

                        case BC_LEX_KEY_LENGTH:
                        case BC_LEX_KEY_SQRT:
                        {
                                if (BC_PARSE_LEAF(prev, rprn))
                                        return bc_error_bad_expression();
                                s = zbc_parse_builtin(p, t, flags, &prev);
                                paren_expr = true;
                                rprn = get_token = bin_last = false;
                                ++nexprs;

                                break;
                        }

                        case BC_LEX_KEY_READ:
                        {
                                if (BC_PARSE_LEAF(prev, rprn))
                                        return bc_error_bad_expression();
                                else if (flags & BC_PARSE_NOREAD)
                                        s = bc_error_nested_read_call();
                                else
                                        s = zbc_parse_read(p);

                                paren_expr = true;
                                rprn = get_token = bin_last = false;
                                ++nexprs;
                                prev = BC_INST_READ;

                                break;
                        }

                        case BC_LEX_KEY_SCALE:
                        {
                                if (BC_PARSE_LEAF(prev, rprn))
                                        return bc_error_bad_expression();
                                s = zbc_parse_scale(p, &prev, flags);
                                paren_expr = true;
                                rprn = get_token = bin_last = false;
                                ++nexprs;
                                prev = BC_INST_SCALE;

                                break;
                        }

                        default:
                        {
                                s = bc_error_bad_token();
                                break;
                        }
                }

                if (!s && get_token) s = zbc_lex_next(&p->l);
        }

        if (s) return s;
        if (G_interrupt) return BC_STATUS_FAILURE; // ^C: stop parsing

        while (p->ops.len > ops_bgn) {

                top = BC_PARSE_TOP_OP(p);
                assign = top >= BC_LEX_OP_ASSIGN_POWER && top <= BC_LEX_OP_ASSIGN;

                if (top == BC_LEX_LPAREN || top == BC_LEX_RPAREN)
                        return bc_error_bad_expression();

                bc_parse_push(p, BC_PARSE_TOKEN_INST(top));

                nexprs -= top != BC_LEX_OP_BOOL_NOT && top != BC_LEX_NEG;
                bc_vec_pop(&p->ops);
        }

        if (prev == BC_INST_BOOL_NOT || nexprs != 1)
                return bc_error_bad_expression();

        // next is BcParseNext, byte array of up to 4 BC_LEX's, packed into 32-bit word
        for (;;) {
                if (t == (next & 0x7f))
                        goto ok;
                if (next & 0x80) // last element?
                        break;
                next >>= 8;
        }
        return bc_error_bad_expression();
 ok:

        if (!(flags & BC_PARSE_REL) && nrelops) {
                s = bc_POSIX_does_not_allow("comparison operators outside if or loops");
                ERROR_RETURN(if (s) return s;)
        }
        else if ((flags & BC_PARSE_REL) && nrelops > 1) {
                s = bc_POSIX_requires("exactly one comparison operator per condition");
                ERROR_RETURN(if (s) return s;)
        }

        if (flags & BC_PARSE_PRINT) {
                if (paren_first || !assign) bc_parse_push(p, BC_INST_PRINT);
                bc_parse_push(p, BC_INST_POP);
        }

        return s;
}

#undef zbc_parse_expr
static BC_STATUS zbc_parse_expr(BcParse *p, uint8_t flags, BcParseNext next)
{
        BcStatus s;

        s = bc_parse_expr_empty_ok(p, flags, next);
        if (s == BC_STATUS_PARSE_EMPTY_EXP)
                RETURN_STATUS(bc_error("empty expression"));
        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_parse_expr(...) (zbc_parse_expr(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_parse_expression(BcParse *p, uint8_t flags)
{
        RETURN_STATUS(zbc_parse_expr(p, flags, bc_parse_next_read));
}
#if ERRORS_ARE_FATAL
# define zbc_parse_expression(...) (zbc_parse_expression(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

#endif // ENABLE_BC

#if ENABLE_DC

#define DC_PARSE_BUF_LEN ((int) (sizeof(uint32_t) * CHAR_BIT))

static BC_STATUS zdc_parse_register(BcParse *p)
{
        BcStatus s;
        char *name;

        s = zbc_lex_next(&p->l);
        if (s) RETURN_STATUS(s);
        if (p->l.t.t != BC_LEX_NAME) RETURN_STATUS(bc_error_bad_token());

        name = xstrdup(p->l.t.v.v);
        bc_parse_pushName(p, name);

        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zdc_parse_register(...) (zdc_parse_register(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zdc_parse_string(BcParse *p)
{
        char *str, *name, b[DC_PARSE_BUF_LEN + 1];
        size_t idx, len = G.prog.strs.len;

        sprintf(b, "%0*zu", DC_PARSE_BUF_LEN, len);
        name = xstrdup(b);

        str = xstrdup(p->l.t.v.v);
        bc_parse_push(p, BC_INST_STR);
        bc_parse_pushIndex(p, len);
        bc_vec_push(&G.prog.strs, &str);
        bc_parse_addFunc(p, name, &idx);

        RETURN_STATUS(zbc_lex_next(&p->l));
}
#if ERRORS_ARE_FATAL
# define zdc_parse_string(...) (zdc_parse_string(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zdc_parse_mem(BcParse *p, uint8_t inst, bool name, bool store)
{
        BcStatus s;

        bc_parse_push(p, inst);
        if (name) {
                s = zdc_parse_register(p);
                if (s) RETURN_STATUS(s);
        }

        if (store) {
                bc_parse_push(p, BC_INST_SWAP);
                bc_parse_push(p, BC_INST_ASSIGN);
                bc_parse_push(p, BC_INST_POP);
        }

        RETURN_STATUS(zbc_lex_next(&p->l));
}
#if ERRORS_ARE_FATAL
# define zdc_parse_mem(...) (zdc_parse_mem(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zdc_parse_cond(BcParse *p, uint8_t inst)
{
        BcStatus s;

        bc_parse_push(p, inst);
        bc_parse_push(p, BC_INST_EXEC_COND);

        s = zdc_parse_register(p);
        if (s) RETURN_STATUS(s);

        s = zbc_lex_next(&p->l);
        if (s) RETURN_STATUS(s);

        if (p->l.t.t == BC_LEX_ELSE) {
                s = zdc_parse_register(p);
                if (s) RETURN_STATUS(s);
                s = zbc_lex_next(&p->l);
        }
        else
                bc_parse_push(p, BC_PARSE_STREND);

        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zdc_parse_cond(...) (zdc_parse_cond(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zdc_parse_token(BcParse *p, BcLexType t, uint8_t flags)
{
        BcStatus s = BC_STATUS_SUCCESS;
        BcInst prev;
        uint8_t inst;
        bool assign, get_token = false;

        switch (t) {
                case BC_LEX_OP_REL_EQ:
                case BC_LEX_OP_REL_LE:
                case BC_LEX_OP_REL_GE:
                case BC_LEX_OP_REL_NE:
                case BC_LEX_OP_REL_LT:
                case BC_LEX_OP_REL_GT:
                        s = zdc_parse_cond(p, t - BC_LEX_OP_REL_EQ + BC_INST_REL_EQ);
                        break;
                case BC_LEX_SCOLON:
                case BC_LEX_COLON:
                        s = zdc_parse_mem(p, BC_INST_ARRAY_ELEM, true, t == BC_LEX_COLON);
                        break;
                case BC_LEX_STR:
                        s = zdc_parse_string(p);
                        break;
                case BC_LEX_NEG:
                case BC_LEX_NUMBER:
                        if (t == BC_LEX_NEG) {
                                s = zbc_lex_next(&p->l);
                                if (s) RETURN_STATUS(s);
                                if (p->l.t.t != BC_LEX_NUMBER)
                                        RETURN_STATUS(bc_error_bad_token());
                        }
                        bc_parse_number(p, &prev, &p->nbraces);
                        if (t == BC_LEX_NEG) bc_parse_push(p, BC_INST_NEG);
                        get_token = true;
                        break;
                case BC_LEX_KEY_READ:
                        if (flags & BC_PARSE_NOREAD)
                                s = bc_error_nested_read_call();
                        else
                                bc_parse_push(p, BC_INST_READ);
                        get_token = true;
                        break;
                case BC_LEX_OP_ASSIGN:
                case BC_LEX_STORE_PUSH:
                        assign = t == BC_LEX_OP_ASSIGN;
                        inst = assign ? BC_INST_VAR : BC_INST_PUSH_TO_VAR;
                        s = zdc_parse_mem(p, inst, true, assign);
                        break;
                case BC_LEX_LOAD:
                case BC_LEX_LOAD_POP:
                        inst = t == BC_LEX_LOAD_POP ? BC_INST_PUSH_VAR : BC_INST_LOAD;
                        s = zdc_parse_mem(p, inst, true, false);
                        break;
                case BC_LEX_STORE_IBASE:
                case BC_LEX_STORE_SCALE:
                case BC_LEX_STORE_OBASE:
                        inst = t - BC_LEX_STORE_IBASE + BC_INST_IBASE;
                        s = zdc_parse_mem(p, inst, false, true);
                        break;
                default:
                        s = bc_error_bad_token();
                        get_token = true;
                        break;
        }

        if (!s && get_token) s = zbc_lex_next(&p->l);

        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zdc_parse_token(...) (zdc_parse_token(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zdc_parse_expr(BcParse *p, uint8_t flags)
{
        BcStatus s = BC_STATUS_SUCCESS;
        BcInst inst;
        BcLexType t;

        if (flags & BC_PARSE_NOCALL) p->nbraces = G.prog.results.len;

        for (t = p->l.t.t; !s && t != BC_LEX_EOF; t = p->l.t.t) {
                inst = dc_parse_insts[t];

                if (inst != BC_INST_INVALID) {
                        bc_parse_push(p, inst);
                        s = zbc_lex_next(&p->l);
                } else
                        s = zdc_parse_token(p, t, flags);
        }

        if (!s && p->l.t.t == BC_LEX_EOF && (flags & BC_PARSE_NOCALL))
                bc_parse_push(p, BC_INST_POP_EXEC);

        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zdc_parse_expr(...) (zdc_parse_expr(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zdc_parse_parse(BcParse *p)
{
        BcStatus s;

        if (p->l.t.t == BC_LEX_EOF)
                s = bc_error("end of file");
        else
                s = zdc_parse_expr(p, 0);

        if (s || G_interrupt) {
                bc_parse_reset(p);
                s = BC_STATUS_FAILURE;
        }

        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zdc_parse_parse(...) (zdc_parse_parse(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

#endif // ENABLE_DC

static BC_STATUS zcommon_parse_expr(BcParse *p, uint8_t flags)
{
        if (IS_BC) {
                IF_BC(RETURN_STATUS(zbc_parse_expression(p, flags));)
        } else {
                IF_DC(RETURN_STATUS(zdc_parse_expr(p, flags));)
        }
}
#if ERRORS_ARE_FATAL
# define zcommon_parse_expr(...) (zcommon_parse_expr(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BcVec* bc_program_search(char *id, bool var)
{
        BcId e, *ptr;
        BcVec *v, *map;
        size_t i;
        BcResultData data;
        int new;

        v = var ? &G.prog.vars : &G.prog.arrs;
        map = var ? &G.prog.var_map : &G.prog.arr_map;

        e.name = id;
        e.idx = v->len;
        new = bc_map_insert(map, &e, &i); // 1 if insertion was successful

        if (new) {
                bc_array_init(&data.v, var);
                bc_vec_push(v, &data.v);
        }

        ptr = bc_vec_item(map, i);
        if (new) ptr->name = xstrdup(e.name);
        return bc_vec_item(v, ptr->idx);
}

static BC_STATUS zbc_program_num(BcResult *r, BcNum **num, bool hex)
{
        switch (r->t) {

                case BC_RESULT_STR:
                case BC_RESULT_TEMP:
                case BC_RESULT_IBASE:
                case BC_RESULT_SCALE:
                case BC_RESULT_OBASE:
                {
                        *num = &r->d.n;
                        break;
                }

                case BC_RESULT_CONSTANT:
                {
                        BcStatus s;
                        char **str = bc_vec_item(&G.prog.consts, r->d.id.idx);
                        size_t base_t, len = strlen(*str);
                        BcNum *base;

                        bc_num_init(&r->d.n, len);

                        hex = hex && len == 1;
                        base = hex ? &G.prog.hexb : &G.prog.ib;
                        base_t = hex ? BC_NUM_MAX_IBASE : G.prog.ib_t;
                        s = zbc_num_parse(&r->d.n, *str, base, base_t);

                        if (s) {
                                bc_num_free(&r->d.n);
                                RETURN_STATUS(s);
                        }

                        *num = &r->d.n;
                        r->t = BC_RESULT_TEMP;

                        break;
                }

                case BC_RESULT_VAR:
                case BC_RESULT_ARRAY:
                case BC_RESULT_ARRAY_ELEM:
                {
                        BcVec *v;

                        v = bc_program_search(r->d.id.name, r->t == BC_RESULT_VAR);

                        if (r->t == BC_RESULT_ARRAY_ELEM) {
                                v = bc_vec_top(v);
                                if (v->len <= r->d.id.idx) bc_array_expand(v, r->d.id.idx + 1);
                                *num = bc_vec_item(v, r->d.id.idx);
                        }
                        else
                                *num = bc_vec_top(v);

                        break;
                }

                case BC_RESULT_LAST:
                {
                        *num = &G.prog.last;
                        break;
                }

                case BC_RESULT_ONE:
                {
                        *num = &G.prog.one;
                        break;
                }
        }

        RETURN_STATUS(BC_STATUS_SUCCESS);
}
#if ERRORS_ARE_FATAL
# define zbc_program_num(...) (zbc_program_num(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_program_binOpPrep(BcResult **l, BcNum **ln,
                                     BcResult **r, BcNum **rn, bool assign)
{
        BcStatus s;
        bool hex;
        BcResultType lt, rt;

        if (!BC_PROG_STACK(&G.prog.results, 2))
                RETURN_STATUS(bc_error_stack_has_too_few_elements());

        *r = bc_vec_item_rev(&G.prog.results, 0);
        *l = bc_vec_item_rev(&G.prog.results, 1);

        lt = (*l)->t;
        rt = (*r)->t;
        hex = assign && (lt == BC_RESULT_IBASE || lt == BC_RESULT_OBASE);

        s = zbc_program_num(*l, ln, false);
        if (s) RETURN_STATUS(s);
        s = zbc_program_num(*r, rn, hex);
        if (s) RETURN_STATUS(s);

        // We run this again under these conditions in case any vector has been
        // reallocated out from under the BcNums or arrays we had.
        if (lt == rt && (lt == BC_RESULT_VAR || lt == BC_RESULT_ARRAY_ELEM)) {
                s = zbc_program_num(*l, ln, false);
                if (s) RETURN_STATUS(s);
        }

        if (!BC_PROG_NUM((*l), (*ln)) && (!assign || (*l)->t != BC_RESULT_VAR))
                RETURN_STATUS(bc_error_variable_is_wrong_type());
        if (!assign && !BC_PROG_NUM((*r), (*ln)))
                RETURN_STATUS(bc_error_variable_is_wrong_type());

        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_program_binOpPrep(...) (zbc_program_binOpPrep(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static void bc_program_binOpRetire(BcResult *r)
{
        r->t = BC_RESULT_TEMP;
        bc_vec_pop(&G.prog.results);
        bc_vec_pop(&G.prog.results);
        bc_vec_push(&G.prog.results, r);
}

static BC_STATUS zbc_program_prep(BcResult **r, BcNum **n)
{
        BcStatus s;

        if (!BC_PROG_STACK(&G.prog.results, 1))
                RETURN_STATUS(bc_error_stack_has_too_few_elements());
        *r = bc_vec_top(&G.prog.results);

        s = zbc_program_num(*r, n, false);
        if (s) RETURN_STATUS(s);

        if (!BC_PROG_NUM((*r), (*n)))
                RETURN_STATUS(bc_error_variable_is_wrong_type());

        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_program_prep(...) (zbc_program_prep(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static void bc_program_retire(BcResult *r, BcResultType t)
{
        r->t = t;
        bc_vec_pop(&G.prog.results);
        bc_vec_push(&G.prog.results, r);
}

static BC_STATUS zbc_program_op(char inst)
{
        BcStatus s;
        BcResult *opd1, *opd2, res;
        BcNum *n1, *n2 = NULL;

        s = zbc_program_binOpPrep(&opd1, &n1, &opd2, &n2, false);
        if (s) RETURN_STATUS(s);
        bc_num_init_DEF_SIZE(&res.d.n);

        s = BC_STATUS_SUCCESS;
        ERROR_RETURN(s =) zbc_program_ops[inst - BC_INST_POWER](n1, n2, &res.d.n, G.prog.scale);
        if (s) goto err;
        bc_program_binOpRetire(&res);

        RETURN_STATUS(s);

err:
        bc_num_free(&res.d.n);
        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_program_op(...) (zbc_program_op(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_program_read(void)
{
        const char *sv_file;
        BcStatus s;
        BcParse parse;
        BcVec buf;
        BcInstPtr ip;
        BcFunc *f;

        if (G.in_read)
                RETURN_STATUS(bc_error_nested_read_call());

        f = bc_program_func(BC_PROG_READ);
        bc_vec_pop_all(&f->code);
        bc_char_vec_init(&buf);

        sv_file = G.prog.file;
        G.prog.file = NULL;
        G.in_read = 1;

        bc_read_line(&buf);

        bc_parse_create(&parse, BC_PROG_READ);
        bc_lex_file(&parse.l);

        s = zbc_parse_text(&parse, buf.v);
        if (s) goto exec_err;
        s = zcommon_parse_expr(&parse, BC_PARSE_NOREAD);
        if (s) goto exec_err;

        if (parse.l.t.t != BC_LEX_NLINE && parse.l.t.t != BC_LEX_EOF) {
                s = bc_error("bad read() expression");
                goto exec_err;
        }

        ip.func = BC_PROG_READ;
        ip.idx = 0;
        ip.len = G.prog.results.len;

        // Update this pointer, just in case.
        f = bc_program_func(BC_PROG_READ);

        bc_vec_pushByte(&f->code, BC_INST_POP_EXEC);
        bc_vec_push(&G.prog.stack, &ip);

exec_err:
        bc_parse_free(&parse);
//io_err:
        G.in_read = 0;
        G.prog.file = sv_file;
        bc_vec_free(&buf);
        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_program_read(...) (zbc_program_read(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static size_t bc_program_index(char *code, size_t *bgn)
{
        char amt = code[(*bgn)++], i = 0;
        size_t res = 0;

        for (; i < amt; ++i, ++(*bgn))
                res |= (((size_t)((int) code[*bgn]) & UCHAR_MAX) << (i * CHAR_BIT));

        return res;
}

static char *bc_program_name(char *code, size_t *bgn)
{
        size_t i;
        char c, *s, *str = code + *bgn, *ptr = strchr(str, BC_PARSE_STREND);

        s = xmalloc(ptr - str + 1);
        c = code[(*bgn)++];

        for (i = 0; c != 0 && c != BC_PARSE_STREND; c = code[(*bgn)++], ++i)
                s[i] = c;

        s[i] = '\0';

        return s;
}

static void bc_program_printString(const char *str)
{
#if ENABLE_DC
        if (!str[0]) {
                // Example: echo '[]ap' | dc
                // should print two bytes: 0x00, 0x0A
                bb_putchar('\0');
                return;
        }
#endif
        while (*str) {
                int c = *str++;
                if (c != '\\' || !*str)
                        bb_putchar(c);
                else {
                        c = *str++;
                        switch (c) {
                        case 'a':
                                bb_putchar('\a');
                                break;
                        case 'b':
                                bb_putchar('\b');
                                break;
                        case '\\':
                        case 'e':
                                bb_putchar('\\');
                                break;
                        case 'f':
                                bb_putchar('\f');
                                break;
                        case 'n':
                                bb_putchar('\n');
                                G.prog.nchars = SIZE_MAX;
                                break;
                        case 'r':
                                bb_putchar('\r');
                                break;
                        case 'q':
                                bb_putchar('"');
                                break;
                        case 't':
                                bb_putchar('\t');
                                break;
                        default:
                                // Just print the backslash and following character.
                                bb_putchar('\\');
                                ++G.prog.nchars;
                                bb_putchar(c);
                                break;
                        }
                }
                ++G.prog.nchars;
        }
}

static void bc_num_printNewline(void)
{
        if (G.prog.nchars == G.prog.len - 1) {
                bb_putchar('\\');
                bb_putchar('\n');
                G.prog.nchars = 0;
        }
}

#if ENABLE_DC
static FAST_FUNC void bc_num_printChar(size_t num, size_t width, bool radix)
{
        (void) radix;
        bb_putchar((char) num);
        G.prog.nchars += width;
}
#endif

static FAST_FUNC void bc_num_printDigits(size_t num, size_t width, bool radix)
{
        size_t exp, pow;

        bc_num_printNewline();
        bb_putchar(radix ? '.' : ' ');
        ++G.prog.nchars;

        bc_num_printNewline();
        for (exp = 0, pow = 1; exp < width - 1; ++exp, pow *= 10)
                continue;

        for (exp = 0; exp < width; pow /= 10, ++G.prog.nchars, ++exp) {
                size_t dig;
                bc_num_printNewline();
                dig = num / pow;
                num -= dig * pow;
                bb_putchar(((char) dig) + '0');
        }
}

static FAST_FUNC void bc_num_printHex(size_t num, size_t width, bool radix)
{
        if (radix) {
                bc_num_printNewline();
                bb_putchar('.');
                G.prog.nchars += 1;
        }

        bc_num_printNewline();
        bb_putchar(bb_hexdigits_upcase[num]);
        G.prog.nchars += width;
}

static void bc_num_printDecimal(BcNum *n)
{
        size_t i, rdx = n->rdx - 1;

        if (n->neg) bb_putchar('-');
        G.prog.nchars += n->neg;

        for (i = n->len - 1; i < n->len; --i)
                bc_num_printHex((size_t) n->num[i], 1, i == rdx);
}

static BC_STATUS zbc_num_printNum(BcNum *n, BcNum *base, size_t width, BcNumDigitOp print)
{
        BcStatus s;
        BcVec stack;
        BcNum intp, fracp, digit, frac_len;
        unsigned long dig, *ptr;
        size_t i;
        bool radix;

        if (n->len == 0) {
                print(0, width, false);
                RETURN_STATUS(BC_STATUS_SUCCESS);
        }

        bc_vec_init(&stack, sizeof(long), NULL);
        bc_num_init(&intp, n->len);
        bc_num_init(&fracp, n->rdx);
        bc_num_init(&digit, width);
        bc_num_init(&frac_len, BC_NUM_INT(n));
        bc_num_copy(&intp, n);
        bc_num_one(&frac_len);

        bc_num_truncate(&intp, intp.rdx);
        s = zbc_num_sub(n, &intp, &fracp, 0);
        if (s) goto err;

        while (intp.len != 0) {
                s = zbc_num_divmod(&intp, base, &intp, &digit, 0);
                if (s) goto err;
                s = zbc_num_ulong(&digit, &dig);
                if (s) goto err;
                bc_vec_push(&stack, &dig);
        }

        for (i = 0; i < stack.len; ++i) {
                ptr = bc_vec_item_rev(&stack, i);
                print(*ptr, width, false);
        }

        if (!n->rdx) goto err;

        for (radix = true; frac_len.len <= n->rdx; radix = false) {
                s = zbc_num_mul(&fracp, base, &fracp, n->rdx);
                if (s) goto err;
                s = zbc_num_ulong(&fracp, &dig);
                if (s) goto err;
                bc_num_ulong2num(&intp, dig);
                s = zbc_num_sub(&fracp, &intp, &fracp, 0);
                if (s) goto err;
                print(dig, width, radix);
                s = zbc_num_mul(&frac_len, base, &frac_len, 0);
                if (s) goto err;
        }

err:
        bc_num_free(&frac_len);
        bc_num_free(&digit);
        bc_num_free(&fracp);
        bc_num_free(&intp);
        bc_vec_free(&stack);
        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_num_printNum(...) (zbc_num_printNum(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_num_printBase(BcNum *n)
{
        BcStatus s;
        size_t width, i;
        BcNumDigitOp print;
        bool neg = n->neg;

        if (neg) {
                bb_putchar('-');
                G.prog.nchars++;
        }

        n->neg = false;

        if (G.prog.ob_t <= BC_NUM_MAX_IBASE) {
                width = 1;
                print = bc_num_printHex;
        }
        else {
                for (i = G.prog.ob_t - 1, width = 0; i != 0; i /= 10, ++width)
                        continue;
                print = bc_num_printDigits;
        }

        s = zbc_num_printNum(n, &G.prog.ob, width, print);
        n->neg = neg;

        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_num_printBase(...) (zbc_num_printBase(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

#if ENABLE_DC
static BC_STATUS zbc_num_stream(BcNum *n, BcNum *base)
{
        RETURN_STATUS(zbc_num_printNum(n, base, 1, bc_num_printChar));
}
#if ERRORS_ARE_FATAL
# define zbc_num_stream(...) (zbc_num_stream(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif
#endif

static BC_STATUS zbc_num_print(BcNum *n, bool newline)
{
        BcStatus s = BC_STATUS_SUCCESS;

        bc_num_printNewline();

        if (n->len == 0) {
                bb_putchar('0');
                ++G.prog.nchars;
        }
        else if (G.prog.ob_t == 10)
                bc_num_printDecimal(n);
        else
                s = zbc_num_printBase(n);

        if (newline) {
                bb_putchar('\n');
                G.prog.nchars = 0;
        }

        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_num_print(...) (zbc_num_print(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_program_print(char inst, size_t idx)
{
        BcStatus s;
        BcResult *r;
        BcNum *num;
        bool pop = inst != BC_INST_PRINT;

        if (!BC_PROG_STACK(&G.prog.results, idx + 1))
                RETURN_STATUS(bc_error_stack_has_too_few_elements());

        r = bc_vec_item_rev(&G.prog.results, idx);
        num = NULL; // is this NULL necessary?
        s = zbc_program_num(r, &num, false);
        if (s) RETURN_STATUS(s);

        if (BC_PROG_NUM(r, num)) {
                s = zbc_num_print(num, !pop);
                if (!s) bc_num_copy(&G.prog.last, num);
        }
        else {
                char *str;

                idx = (r->t == BC_RESULT_STR) ? r->d.id.idx : num->rdx;
                str = *bc_program_str(idx);

                if (inst == BC_INST_PRINT_STR) {
                        for (;;) {
                                char c = *str++;
                                if (c == '\0') break;
                                bb_putchar(c);
                                ++G.prog.nchars;
                                if (c == '\n') G.prog.nchars = 0;
                        }
                }
                else {
                        bc_program_printString(str);
                        if (inst == BC_INST_PRINT) bb_putchar('\n');
                }
        }

        if (!s && pop) bc_vec_pop(&G.prog.results);

        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_program_print(...) (zbc_program_print(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_program_negate(void)
{
        BcStatus s;
        BcResult res, *ptr;
        BcNum *num = NULL;

        s = zbc_program_prep(&ptr, &num);
        if (s) RETURN_STATUS(s);

        bc_num_init(&res.d.n, num->len);
        bc_num_copy(&res.d.n, num);
        if (res.d.n.len) res.d.n.neg = !res.d.n.neg;

        bc_program_retire(&res, BC_RESULT_TEMP);

        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_program_negate(...) (zbc_program_negate(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_program_logical(char inst)
{
        BcStatus s;
        BcResult *opd1, *opd2, res;
        BcNum *n1, *n2;
        ssize_t cond;

        s = zbc_program_binOpPrep(&opd1, &n1, &opd2, &n2, false);
        if (s) RETURN_STATUS(s);

        bc_num_init_DEF_SIZE(&res.d.n);

        if (inst == BC_INST_BOOL_AND)
                cond = bc_num_cmp(n1, &G.prog.zero) && bc_num_cmp(n2, &G.prog.zero);
        else if (inst == BC_INST_BOOL_OR)
                cond = bc_num_cmp(n1, &G.prog.zero) || bc_num_cmp(n2, &G.prog.zero);
        else {
                cond = bc_num_cmp(n1, n2);
                switch (inst) {
                case BC_INST_REL_EQ:
                        cond = (cond == 0);
                        break;
                case BC_INST_REL_LE:
                        cond = (cond <= 0);
                        break;
                case BC_INST_REL_GE:
                        cond = (cond >= 0);
                        break;
                case BC_INST_REL_LT:
                        cond = (cond < 0);
                        break;
                case BC_INST_REL_GT:
                        cond = (cond > 0);
                        break;
                default: // = case BC_INST_REL_NE:
                        //cond = (cond != 0); - not needed
                        break;
                }
        }

        if (cond) bc_num_one(&res.d.n);
        //else bc_num_zero(&res.d.n); - already is

        bc_program_binOpRetire(&res);

        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_program_logical(...) (zbc_program_logical(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

#if ENABLE_DC
static BC_STATUS zbc_program_assignStr(BcResult *r, BcVec *v,
                                     bool push)
{
        BcNum n2;
        BcResult res;

        memset(&n2, 0, sizeof(BcNum));
        n2.rdx = res.d.id.idx = r->d.id.idx;
        res.t = BC_RESULT_STR;

        if (!push) {
                if (!BC_PROG_STACK(&G.prog.results, 2))
                        RETURN_STATUS(bc_error_stack_has_too_few_elements());
                bc_vec_pop(v);
                bc_vec_pop(&G.prog.results);
        }

        bc_vec_pop(&G.prog.results);

        bc_vec_push(&G.prog.results, &res);
        bc_vec_push(v, &n2);

        RETURN_STATUS(BC_STATUS_SUCCESS);
}
#if ERRORS_ARE_FATAL
# define zbc_program_assignStr(...) (zbc_program_assignStr(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif
#endif // ENABLE_DC

static BC_STATUS zbc_program_copyToVar(char *name, bool var)
{
        BcStatus s;
        BcResult *ptr, r;
        BcVec *v;
        BcNum *n;

        if (!BC_PROG_STACK(&G.prog.results, 1))
                RETURN_STATUS(bc_error_stack_has_too_few_elements());

        ptr = bc_vec_top(&G.prog.results);
        if ((ptr->t == BC_RESULT_ARRAY) != !var)
                RETURN_STATUS(bc_error_variable_is_wrong_type());
        v = bc_program_search(name, var);

#if ENABLE_DC
        if (ptr->t == BC_RESULT_STR && !var)
                RETURN_STATUS(bc_error_variable_is_wrong_type());
        if (ptr->t == BC_RESULT_STR)
                RETURN_STATUS(zbc_program_assignStr(ptr, v, true));
#endif

        s = zbc_program_num(ptr, &n, false);
        if (s) RETURN_STATUS(s);

        // Do this once more to make sure that pointers were not invalidated.
        v = bc_program_search(name, var);

        if (var) {
                bc_num_init_DEF_SIZE(&r.d.n);
                bc_num_copy(&r.d.n, n);
        }
        else {
                bc_array_init(&r.d.v, true);
                bc_array_copy(&r.d.v, (BcVec *) n);
        }

        bc_vec_push(v, &r.d);
        bc_vec_pop(&G.prog.results);

        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_program_copyToVar(...) (zbc_program_copyToVar(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_program_assign(char inst)
{
        BcStatus s;
        BcResult *left, *right, res;
        BcNum *l = NULL, *r = NULL;
        bool assign = inst == BC_INST_ASSIGN, ib, sc;

        s = zbc_program_binOpPrep(&left, &l, &right, &r, assign);
        if (s) RETURN_STATUS(s);

        ib = left->t == BC_RESULT_IBASE;
        sc = left->t == BC_RESULT_SCALE;

#if ENABLE_DC

        if (right->t == BC_RESULT_STR) {

                BcVec *v;

                if (left->t != BC_RESULT_VAR)
                        RETURN_STATUS(bc_error_variable_is_wrong_type());
                v = bc_program_search(left->d.id.name, true);

                RETURN_STATUS(zbc_program_assignStr(right, v, false));
        }
#endif

        if (left->t == BC_RESULT_CONSTANT || left->t == BC_RESULT_TEMP)
                RETURN_STATUS(bc_error("bad assignment:"
                                " left side must be scale,"
                                " ibase, obase, last, var,"
                                " or array element"
                ));

#if ENABLE_BC
        if (inst == BC_INST_ASSIGN_DIVIDE && !bc_num_cmp(r, &G.prog.zero))
                RETURN_STATUS(bc_error("divide by zero"));

        if (assign)
                bc_num_copy(l, r);
        else {
                s = BC_STATUS_SUCCESS;
                ERROR_RETURN(s =) zbc_program_ops[inst - BC_INST_ASSIGN_POWER](l, r, l, G.prog.scale);
        }
        if (s) RETURN_STATUS(s);
#else
        bc_num_copy(l, r);
#endif

        if (ib || sc || left->t == BC_RESULT_OBASE) {
                static const char *const msg[] = {
                        "bad ibase; must be [2,16]",                 //BC_RESULT_IBASE
                        "bad scale; must be [0,"BC_MAX_SCALE_STR"]", //BC_RESULT_SCALE
                        NULL, //can't happen                         //BC_RESULT_LAST
                        NULL, //can't happen                         //BC_RESULT_CONSTANT
                        NULL, //can't happen                         //BC_RESULT_ONE
                        "bad obase; must be [2,"BC_MAX_OBASE_STR"]", //BC_RESULT_OBASE
                };
                size_t *ptr;
                unsigned long val, max;

                s = zbc_num_ulong(l, &val);
                if (s) RETURN_STATUS(s);
                s = left->t - BC_RESULT_IBASE;
                if (sc) {
                        max = BC_MAX_SCALE;
                        ptr = &G.prog.scale;
                }
                else {
                        if (val < BC_NUM_MIN_BASE)
                                RETURN_STATUS(bc_error(msg[s]));
                        max = ib ? BC_NUM_MAX_IBASE : BC_MAX_OBASE;
                        ptr = ib ? &G.prog.ib_t : &G.prog.ob_t;
                }

                if (val > max)
                        RETURN_STATUS(bc_error(msg[s]));
                if (!sc)
                        bc_num_copy(ib ? &G.prog.ib : &G.prog.ob, l);

                *ptr = (size_t) val;
                s = BC_STATUS_SUCCESS;
        }

        bc_num_init(&res.d.n, l->len);
        bc_num_copy(&res.d.n, l);
        bc_program_binOpRetire(&res);

        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_program_assign(...) (zbc_program_assign(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

#if !ENABLE_DC
#define bc_program_pushVar(code, bgn, pop, copy) \
        bc_program_pushVar(code, bgn)
// for bc, 'pop' and 'copy' are always false
#endif
static BC_STATUS bc_program_pushVar(char *code, size_t *bgn,
                                   bool pop, bool copy)
{
        BcResult r;
        char *name = bc_program_name(code, bgn);

        r.t = BC_RESULT_VAR;
        r.d.id.name = name;

#if ENABLE_DC
        {
                BcVec *v = bc_program_search(name, true);
                BcNum *num = bc_vec_top(v);

                if (pop || copy) {

                        if (!BC_PROG_STACK(v, 2 - copy)) {
                                free(name);
                                RETURN_STATUS(bc_error_stack_has_too_few_elements());
                        }

                        free(name);
                        name = NULL;

                        if (!BC_PROG_STR(num)) {

                                r.t = BC_RESULT_TEMP;

                                bc_num_init_DEF_SIZE(&r.d.n);
                                bc_num_copy(&r.d.n, num);
                        }
                        else {
                                r.t = BC_RESULT_STR;
                                r.d.id.idx = num->rdx;
                        }

                        if (!copy) bc_vec_pop(v);
                }
        }
#endif // ENABLE_DC

        bc_vec_push(&G.prog.results, &r);

        RETURN_STATUS(BC_STATUS_SUCCESS);
}
#if ERRORS_ARE_FATAL
# define zbc_program_pushVar(...) (bc_program_pushVar(__VA_ARGS__), BC_STATUS_SUCCESS)
#else
# define zbc_program_pushVar(...) bc_program_pushVar(__VA_ARGS__)
#endif

static BC_STATUS zbc_program_pushArray(char *code, size_t *bgn,
                                     char inst)
{
        BcStatus s = BC_STATUS_SUCCESS;
        BcResult r;
        BcNum *num;

        r.d.id.name = bc_program_name(code, bgn);

        if (inst == BC_INST_ARRAY) {
                r.t = BC_RESULT_ARRAY;
                bc_vec_push(&G.prog.results, &r);
        }
        else {

                BcResult *operand;
                unsigned long temp;

                s = zbc_program_prep(&operand, &num);
                if (s) goto err;
                s = zbc_num_ulong(num, &temp);
                if (s) goto err;

                if (temp > BC_MAX_DIM) {
                        s = bc_error("array too long; must be [1,"BC_MAX_DIM_STR"]");
                        goto err;
                }

                r.d.id.idx = (size_t) temp;
                bc_program_retire(&r, BC_RESULT_ARRAY_ELEM);
        }

err:
        if (s) free(r.d.id.name);
        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_program_pushArray(...) (zbc_program_pushArray(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

#if ENABLE_BC
static BC_STATUS zbc_program_incdec(char inst)
{
        BcStatus s;
        BcResult *ptr, res, copy;
        BcNum *num = NULL;
        char inst2 = inst;

        s = zbc_program_prep(&ptr, &num);
        if (s) RETURN_STATUS(s);

        if (inst == BC_INST_INC_POST || inst == BC_INST_DEC_POST) {
                copy.t = BC_RESULT_TEMP;
                bc_num_init(&copy.d.n, num->len);
                bc_num_copy(&copy.d.n, num);
        }

        res.t = BC_RESULT_ONE;
        inst = inst == BC_INST_INC_PRE || inst == BC_INST_INC_POST ?
                   BC_INST_ASSIGN_PLUS :
                   BC_INST_ASSIGN_MINUS;

        bc_vec_push(&G.prog.results, &res);
        s = zbc_program_assign(inst);
        if (s) RETURN_STATUS(s);

        if (inst2 == BC_INST_INC_POST || inst2 == BC_INST_DEC_POST) {
                bc_vec_pop(&G.prog.results);
                bc_vec_push(&G.prog.results, &copy);
        }

        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_program_incdec(...) (zbc_program_incdec(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_program_call(char *code, size_t *idx)
{
        BcInstPtr ip;
        size_t i, nparams = bc_program_index(code, idx);
        BcFunc *func;
        BcId *a;
        BcResultData param;
        BcResult *arg;

        ip.idx = 0;
        ip.func = bc_program_index(code, idx);
        func = bc_program_func(ip.func);

        if (func->code.len == 0) {
                RETURN_STATUS(bc_error("undefined function"));
        }
        if (nparams != func->nparams) {
                RETURN_STATUS(bc_error_fmt("function has %u parameters, but called with %u", func->nparams, nparams));
        }
        ip.len = G.prog.results.len - nparams;

        for (i = 0; i < nparams; ++i) {
                BcStatus s;

                a = bc_vec_item(&func->autos, nparams - 1 - i);
                arg = bc_vec_top(&G.prog.results);

                if ((!a->idx) != (arg->t == BC_RESULT_ARRAY) || arg->t == BC_RESULT_STR)
                        RETURN_STATUS(bc_error_variable_is_wrong_type());

                s = zbc_program_copyToVar(a->name, a->idx);
                if (s) RETURN_STATUS(s);
        }

        for (; i < func->autos.len; ++i) {
                BcVec *v;

                a = bc_vec_item(&func->autos, i);
                v = bc_program_search(a->name, a->idx);

                if (a->idx) {
                        bc_num_init_DEF_SIZE(&param.n);
                        bc_vec_push(v, &param.n);
                }
                else {
                        bc_array_init(&param.v, true);
                        bc_vec_push(v, &param.v);
                }
        }

        bc_vec_push(&G.prog.stack, &ip);

        RETURN_STATUS(BC_STATUS_SUCCESS);
}
#if ERRORS_ARE_FATAL
# define zbc_program_call(...) (zbc_program_call(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_program_return(char inst)
{
        BcResult res;
        BcFunc *f;
        size_t i;
        BcInstPtr *ip = bc_vec_top(&G.prog.stack);

        if (!BC_PROG_STACK(&G.prog.results, ip->len + inst == BC_INST_RET))
                RETURN_STATUS(bc_error_stack_has_too_few_elements());

        f = bc_program_func(ip->func);
        res.t = BC_RESULT_TEMP;

        if (inst == BC_INST_RET) {
                BcStatus s;
                BcNum *num;
                BcResult *operand = bc_vec_top(&G.prog.results);

                s = zbc_program_num(operand, &num, false);
                if (s) RETURN_STATUS(s);
                bc_num_init(&res.d.n, num->len);
                bc_num_copy(&res.d.n, num);
        }
        else {
                bc_num_init_DEF_SIZE(&res.d.n);
                //bc_num_zero(&res.d.n); - already is
        }

        // We need to pop arguments as well, so this takes that into account.
        for (i = 0; i < f->autos.len; ++i) {
                BcVec *v;
                BcId *a = bc_vec_item(&f->autos, i);

                v = bc_program_search(a->name, a->idx);
                bc_vec_pop(v);
        }

        bc_vec_npop(&G.prog.results, G.prog.results.len - ip->len);
        bc_vec_push(&G.prog.results, &res);
        bc_vec_pop(&G.prog.stack);

        RETURN_STATUS(BC_STATUS_SUCCESS);
}
#if ERRORS_ARE_FATAL
# define zbc_program_return(...) (zbc_program_return(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif
#endif // ENABLE_BC

static unsigned long bc_program_scale(BcNum *n)
{
        return (unsigned long) n->rdx;
}

static unsigned long bc_program_len(BcNum *n)
{
        size_t len = n->len;

        if (n->rdx != len) return len;
        for (;;) {
                if (len == 0) break;
                len--;
                if (n->num[len] != 0) break;
        }
        return len;
}

static BC_STATUS zbc_program_builtin(char inst)
{
        BcStatus s;
        BcResult *opnd;
        BcNum *num = NULL;
        BcResult res;
        bool len = inst == BC_INST_LENGTH;

        if (!BC_PROG_STACK(&G.prog.results, 1))
                RETURN_STATUS(bc_error_stack_has_too_few_elements());
        opnd = bc_vec_top(&G.prog.results);

        s = zbc_program_num(opnd, &num, false);
        if (s) RETURN_STATUS(s);

#if ENABLE_DC
        if (!BC_PROG_NUM(opnd, num) && !len)
                RETURN_STATUS(bc_error_variable_is_wrong_type());
#endif

        bc_num_init_DEF_SIZE(&res.d.n);

        if (inst == BC_INST_SQRT) s = zbc_num_sqrt(num, &res.d.n, G.prog.scale);
#if ENABLE_BC
        else if (len != 0 && opnd->t == BC_RESULT_ARRAY) {
                bc_num_ulong2num(&res.d.n, (unsigned long) ((BcVec *) num)->len);
        }
#endif
#if ENABLE_DC
        else if (len != 0 && !BC_PROG_NUM(opnd, num)) {
                char **str;
                size_t idx = opnd->t == BC_RESULT_STR ? opnd->d.id.idx : num->rdx;

                str = bc_program_str(idx);
                bc_num_ulong2num(&res.d.n, strlen(*str));
        }
#endif
        else {
                bc_num_ulong2num(&res.d.n, len ? bc_program_len(num) : bc_program_scale(num));
        }

        bc_program_retire(&res, BC_RESULT_TEMP);

        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_program_builtin(...) (zbc_program_builtin(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

#if ENABLE_DC
static BC_STATUS zbc_program_divmod(void)
{
        BcStatus s;
        BcResult *opd1, *opd2, res, res2;
        BcNum *n1, *n2 = NULL;

        s = zbc_program_binOpPrep(&opd1, &n1, &opd2, &n2, false);
        if (s) RETURN_STATUS(s);

        bc_num_init_DEF_SIZE(&res.d.n);
        bc_num_init(&res2.d.n, n2->len);

        s = zbc_num_divmod(n1, n2, &res2.d.n, &res.d.n, G.prog.scale);
        if (s) goto err;

        bc_program_binOpRetire(&res2);
        res.t = BC_RESULT_TEMP;
        bc_vec_push(&G.prog.results, &res);

        RETURN_STATUS(s);

err:
        bc_num_free(&res2.d.n);
        bc_num_free(&res.d.n);
        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_program_divmod(...) (zbc_program_divmod(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_program_modexp(void)
{
        BcStatus s;
        BcResult *r1, *r2, *r3, res;
        BcNum *n1, *n2, *n3;

        if (!BC_PROG_STACK(&G.prog.results, 3))
                RETURN_STATUS(bc_error_stack_has_too_few_elements());
        s = zbc_program_binOpPrep(&r2, &n2, &r3, &n3, false);
        if (s) RETURN_STATUS(s);

        r1 = bc_vec_item_rev(&G.prog.results, 2);
        s = zbc_program_num(r1, &n1, false);
        if (s) RETURN_STATUS(s);
        if (!BC_PROG_NUM(r1, n1))
                RETURN_STATUS(bc_error_variable_is_wrong_type());

        // Make sure that the values have their pointers updated, if necessary.
        if (r1->t == BC_RESULT_VAR || r1->t == BC_RESULT_ARRAY_ELEM) {

                if (r1->t == r2->t) {
                        s = zbc_program_num(r2, &n2, false);
                        if (s) RETURN_STATUS(s);
                }

                if (r1->t == r3->t) {
                        s = zbc_program_num(r3, &n3, false);
                        if (s) RETURN_STATUS(s);
                }
        }

        bc_num_init(&res.d.n, n3->len);
        s = zbc_num_modexp(n1, n2, n3, &res.d.n);
        if (s) goto err;

        bc_vec_pop(&G.prog.results);
        bc_program_binOpRetire(&res);

        RETURN_STATUS(s);

err:
        bc_num_free(&res.d.n);
        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_program_modexp(...) (zbc_program_modexp(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static void bc_program_stackLen(void)
{
        BcResult res;
        size_t len = G.prog.results.len;

        res.t = BC_RESULT_TEMP;

        bc_num_init_DEF_SIZE(&res.d.n);
        bc_num_ulong2num(&res.d.n, len);
        bc_vec_push(&G.prog.results, &res);
}

static BC_STATUS zbc_program_asciify(void)
{
        BcStatus s;
        BcResult *r, res;
        BcNum *num, n;
        char *str, *str2, c;
        size_t len = G.prog.strs.len, idx;
        unsigned long val;

        if (!BC_PROG_STACK(&G.prog.results, 1))
                RETURN_STATUS(bc_error_stack_has_too_few_elements());
        r = bc_vec_top(&G.prog.results);

        num = NULL; // TODO: is this NULL needed?
        s = zbc_program_num(r, &num, false);
        if (s) RETURN_STATUS(s);

        if (BC_PROG_NUM(r, num)) {

                bc_num_init_DEF_SIZE(&n);
                bc_num_copy(&n, num);
                bc_num_truncate(&n, n.rdx);

                s = zbc_num_mod(&n, &G.prog.strmb, &n, 0);
                if (s) goto num_err;
                s = zbc_num_ulong(&n, &val);
                if (s) goto num_err;

                c = (char) val;

                bc_num_free(&n);
        }
        else {
                idx = (r->t == BC_RESULT_STR) ? r->d.id.idx : num->rdx;
                str2 = *bc_program_str(idx);
                c = str2[0];
        }

        str = xzalloc(2);
        str[0] = c;
        //str[1] = '\0'; - already is

        str2 = xstrdup(str);
        bc_program_addFunc(str2, &idx);

        if (idx != len + BC_PROG_REQ_FUNCS) {
                for (idx = 0; idx < G.prog.strs.len; ++idx) {
                        if (strcmp(*bc_program_str(idx), str) == 0) {
                                len = idx;
                                break;
                        }
                }

                free(str);
        }
        else
                bc_vec_push(&G.prog.strs, &str);

        res.t = BC_RESULT_STR;
        res.d.id.idx = len;
        bc_vec_pop(&G.prog.results);
        bc_vec_push(&G.prog.results, &res);

        RETURN_STATUS(BC_STATUS_SUCCESS);

num_err:
        bc_num_free(&n);
        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_program_asciify(...) (zbc_program_asciify(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_program_printStream(void)
{
        BcStatus s;
        BcResult *r;
        BcNum *n = NULL;
        size_t idx;
        char *str;

        if (!BC_PROG_STACK(&G.prog.results, 1))
                RETURN_STATUS(bc_error_stack_has_too_few_elements());
        r = bc_vec_top(&G.prog.results);

        s = zbc_program_num(r, &n, false);
        if (s) RETURN_STATUS(s);

        if (BC_PROG_NUM(r, n))
                s = zbc_num_stream(n, &G.prog.strmb);
        else {
                idx = (r->t == BC_RESULT_STR) ? r->d.id.idx : n->rdx;
                str = *bc_program_str(idx);
                printf("%s", str);
        }

        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_program_printStream(...) (zbc_program_printStream(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_program_nquit(void)
{
        BcStatus s;
        BcResult *opnd;
        BcNum *num = NULL;
        unsigned long val;

        s = zbc_program_prep(&opnd, &num);
        if (s) RETURN_STATUS(s);
        s = zbc_num_ulong(num, &val);
        if (s) RETURN_STATUS(s);

        bc_vec_pop(&G.prog.results);

        if (G.prog.stack.len < val)
                RETURN_STATUS(bc_error_stack_has_too_few_elements());
        if (G.prog.stack.len == val) {
                QUIT_OR_RETURN_TO_MAIN;
        }

        bc_vec_npop(&G.prog.stack, val);

        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_program_nquit(...) (zbc_program_nquit(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_program_execStr(char *code, size_t *bgn,
                                   bool cond)
{
        BcStatus s = BC_STATUS_SUCCESS;
        BcResult *r;
        char **str;
        BcFunc *f;
        BcParse prs;
        BcInstPtr ip;
        size_t fidx, sidx;

        if (!BC_PROG_STACK(&G.prog.results, 1))
                RETURN_STATUS(bc_error_stack_has_too_few_elements());

        r = bc_vec_top(&G.prog.results);

        if (cond) {
                BcNum *n = n; // for compiler
                bool exec;
                char *name;
                char *then_name = bc_program_name(code, bgn);
                char *else_name = NULL;

                if (code[*bgn] == BC_PARSE_STREND)
                        (*bgn) += 1;
                else
                        else_name = bc_program_name(code, bgn);

                exec = r->d.n.len != 0;
                name = then_name;
                if (!exec && else_name != NULL) {
                        exec = true;
                        name = else_name;
                }

                if (exec) {
                        BcVec *v;
                        v = bc_program_search(name, true);
                        n = bc_vec_top(v);
                }

                free(then_name);
                free(else_name);

                if (!exec) goto exit;
                if (!BC_PROG_STR(n)) {
                        s = bc_error_variable_is_wrong_type();
                        goto exit;
                }

                sidx = n->rdx;
        } else {
                if (r->t == BC_RESULT_STR) {
                        sidx = r->d.id.idx;
                } else if (r->t == BC_RESULT_VAR) {
                        BcNum *n;
                        s = zbc_program_num(r, &n, false);
                        if (s || !BC_PROG_STR(n)) goto exit;
                        sidx = n->rdx;
                } else
                        goto exit;
        }

        fidx = sidx + BC_PROG_REQ_FUNCS;

        str = bc_program_str(sidx);
        f = bc_program_func(fidx);

        if (f->code.len == 0) {
                bc_parse_create(&prs, fidx);
                s = zbc_parse_text(&prs, *str);
                if (s) goto err;
                s = zcommon_parse_expr(&prs, BC_PARSE_NOCALL);
                if (s) goto err;

                if (prs.l.t.t != BC_LEX_EOF) {
                        s = bc_error_bad_expression();
                        goto err;
                }

                bc_parse_free(&prs);
        }

        ip.idx = 0;
        ip.len = G.prog.results.len;
        ip.func = fidx;

        bc_vec_pop(&G.prog.results);
        bc_vec_push(&G.prog.stack, &ip);

        RETURN_STATUS(BC_STATUS_SUCCESS);

err:
        bc_parse_free(&prs);
        f = bc_program_func(fidx);
        bc_vec_pop_all(&f->code);
exit:
        bc_vec_pop(&G.prog.results);
        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_program_execStr(...) (zbc_program_execStr(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif
#endif // ENABLE_DC

static void bc_program_pushGlobal(char inst)
{
        BcResult res;
        unsigned long val;

        res.t = inst - BC_INST_IBASE + BC_RESULT_IBASE;
        if (inst == BC_INST_IBASE)
                val = (unsigned long) G.prog.ib_t;
        else if (inst == BC_INST_SCALE)
                val = (unsigned long) G.prog.scale;
        else
                val = (unsigned long) G.prog.ob_t;

        bc_num_init_DEF_SIZE(&res.d.n);
        bc_num_ulong2num(&res.d.n, val);
        bc_vec_push(&G.prog.results, &res);
}

static void bc_program_addFunc(char *name, size_t *idx)
{
        BcId entry, *entry_ptr;
        BcFunc f;
        int inserted;

        entry.name = name;
        entry.idx = G.prog.fns.len;

        inserted = bc_map_insert(&G.prog.fn_map, &entry, idx);
        if (!inserted) free(name);

        entry_ptr = bc_vec_item(&G.prog.fn_map, *idx);
        *idx = entry_ptr->idx;

        if (!inserted) {

                BcFunc *func = bc_program_func(entry_ptr->idx);

                // We need to reset these, so the function can be repopulated.
                func->nparams = 0;
                bc_vec_pop_all(&func->autos);
                bc_vec_pop_all(&func->code);
                bc_vec_pop_all(&func->labels);
        }
        else {
                bc_func_init(&f);
                bc_vec_push(&G.prog.fns, &f);
        }
}

static BC_STATUS zbc_program_exec(void)
{
        BcResult r, *ptr;
        BcNum *num;
        BcInstPtr *ip = bc_vec_top(&G.prog.stack);
        BcFunc *func = bc_program_func(ip->func);
        char *code = func->code.v;
        bool cond = false;

        while (ip->idx < func->code.len) {
                BcStatus s = BC_STATUS_SUCCESS;
                char inst = code[(ip->idx)++];

                switch (inst) {
#if ENABLE_BC
                        case BC_INST_JUMP_ZERO:
                                s = zbc_program_prep(&ptr, &num);
                                if (s) RETURN_STATUS(s);
                                cond = !bc_num_cmp(num, &G.prog.zero);
                                bc_vec_pop(&G.prog.results);
                                // Fallthrough.
                        case BC_INST_JUMP: {
                                size_t *addr;
                                size_t idx = bc_program_index(code, &ip->idx);
                                addr = bc_vec_item(&func->labels, idx);
                                if (inst == BC_INST_JUMP || cond) ip->idx = *addr;
                                break;
                        }
                        case BC_INST_CALL:
                                s = zbc_program_call(code, &ip->idx);
                                break;
                        case BC_INST_INC_PRE:
                        case BC_INST_DEC_PRE:
                        case BC_INST_INC_POST:
                        case BC_INST_DEC_POST:
                                s = zbc_program_incdec(inst);
                                break;
                        case BC_INST_HALT:
                                QUIT_OR_RETURN_TO_MAIN;
                                break;
                        case BC_INST_RET:
                        case BC_INST_RET0:
                                s = zbc_program_return(inst);
                                break;
                        case BC_INST_BOOL_OR:
                        case BC_INST_BOOL_AND:
#endif // ENABLE_BC
                        case BC_INST_REL_EQ:
                        case BC_INST_REL_LE:
                        case BC_INST_REL_GE:
                        case BC_INST_REL_NE:
                        case BC_INST_REL_LT:
                        case BC_INST_REL_GT:
                                s = zbc_program_logical(inst);
                                break;
                        case BC_INST_READ:
                                s = zbc_program_read();
                                break;
                        case BC_INST_VAR:
                                s = zbc_program_pushVar(code, &ip->idx, false, false);
                                break;
                        case BC_INST_ARRAY_ELEM:
                        case BC_INST_ARRAY:
                                s = zbc_program_pushArray(code, &ip->idx, inst);
                                break;
                        case BC_INST_LAST:
                                r.t = BC_RESULT_LAST;
                                bc_vec_push(&G.prog.results, &r);
                                break;
                        case BC_INST_IBASE:
                        case BC_INST_SCALE:
                        case BC_INST_OBASE:
                                bc_program_pushGlobal(inst);
                                break;
                        case BC_INST_SCALE_FUNC:
                        case BC_INST_LENGTH:
                        case BC_INST_SQRT:
                                s = zbc_program_builtin(inst);
                                break;
                        case BC_INST_NUM:
                                r.t = BC_RESULT_CONSTANT;
                                r.d.id.idx = bc_program_index(code, &ip->idx);
                                bc_vec_push(&G.prog.results, &r);
                                break;
                        case BC_INST_POP:
                                if (!BC_PROG_STACK(&G.prog.results, 1))
                                        s = bc_error_stack_has_too_few_elements();
                                else
                                        bc_vec_pop(&G.prog.results);
                                break;
                        case BC_INST_POP_EXEC:
                                bc_vec_pop(&G.prog.stack);
                                break;
                        case BC_INST_PRINT:
                        case BC_INST_PRINT_POP:
                        case BC_INST_PRINT_STR:
                                s = zbc_program_print(inst, 0);
                                break;
                        case BC_INST_STR:
                                r.t = BC_RESULT_STR;
                                r.d.id.idx = bc_program_index(code, &ip->idx);
                                bc_vec_push(&G.prog.results, &r);
                                break;
                        case BC_INST_POWER:
                        case BC_INST_MULTIPLY:
                        case BC_INST_DIVIDE:
                        case BC_INST_MODULUS:
                        case BC_INST_PLUS:
                        case BC_INST_MINUS:
                                s = zbc_program_op(inst);
                                break;
                        case BC_INST_BOOL_NOT:
                                s = zbc_program_prep(&ptr, &num);
                                if (s) RETURN_STATUS(s);
                                bc_num_init_DEF_SIZE(&r.d.n);
                                if (!bc_num_cmp(num, &G.prog.zero))
                                        bc_num_one(&r.d.n);
                                //else bc_num_zero(&r.d.n); - already is
                                bc_program_retire(&r, BC_RESULT_TEMP);
                                break;
                        case BC_INST_NEG:
                                s = zbc_program_negate();
                                break;
#if ENABLE_BC
                        case BC_INST_ASSIGN_POWER:
                        case BC_INST_ASSIGN_MULTIPLY:
                        case BC_INST_ASSIGN_DIVIDE:
                        case BC_INST_ASSIGN_MODULUS:
                        case BC_INST_ASSIGN_PLUS:
                        case BC_INST_ASSIGN_MINUS:
#endif
                        case BC_INST_ASSIGN:
                                s = zbc_program_assign(inst);
                                break;
#if ENABLE_DC
                        case BC_INST_MODEXP:
                                s = zbc_program_modexp();
                                break;
                        case BC_INST_DIVMOD:
                                s = zbc_program_divmod();
                                break;
                        case BC_INST_EXECUTE:
                        case BC_INST_EXEC_COND:
                                cond = inst == BC_INST_EXEC_COND;
                                s = zbc_program_execStr(code, &ip->idx, cond);
                                break;
                        case BC_INST_PRINT_STACK: {
                                size_t idx;
                                for (idx = 0; idx < G.prog.results.len; ++idx) {
                                        s = zbc_program_print(BC_INST_PRINT, idx);
                                        if (s) break;
                                }
                                break;
                        }
                        case BC_INST_CLEAR_STACK:
                                bc_vec_pop_all(&G.prog.results);
                                break;
                        case BC_INST_STACK_LEN:
                                bc_program_stackLen();
                                break;
                        case BC_INST_DUPLICATE:
                                if (!BC_PROG_STACK(&G.prog.results, 1))
                                        RETURN_STATUS(bc_error_stack_has_too_few_elements());
                                ptr = bc_vec_top(&G.prog.results);
                                bc_result_copy(&r, ptr);
                                bc_vec_push(&G.prog.results, &r);
                                break;
                        case BC_INST_SWAP: {
                                BcResult *ptr2;
                                if (!BC_PROG_STACK(&G.prog.results, 2))
                                        RETURN_STATUS(bc_error_stack_has_too_few_elements());
                                ptr = bc_vec_item_rev(&G.prog.results, 0);
                                ptr2 = bc_vec_item_rev(&G.prog.results, 1);
                                memcpy(&r, ptr, sizeof(BcResult));
                                memcpy(ptr, ptr2, sizeof(BcResult));
                                memcpy(ptr2, &r, sizeof(BcResult));
                                break;
                        }
                        case BC_INST_ASCIIFY:
                                s = zbc_program_asciify();
                                break;
                        case BC_INST_PRINT_STREAM:
                                s = zbc_program_printStream();
                                break;
                        case BC_INST_LOAD:
                        case BC_INST_PUSH_VAR: {
                                bool copy = inst == BC_INST_LOAD;
                                s = zbc_program_pushVar(code, &ip->idx, true, copy);
                                break;
                        }
                        case BC_INST_PUSH_TO_VAR: {
                                char *name = bc_program_name(code, &ip->idx);
                                s = zbc_program_copyToVar(name, true);
                                free(name);
                                break;
                        }
                        case BC_INST_QUIT:
                                if (G.prog.stack.len <= 2)
                                        QUIT_OR_RETURN_TO_MAIN;
                                bc_vec_npop(&G.prog.stack, 2);
                                break;
                        case BC_INST_NQUIT:
                                s = zbc_program_nquit();
                                break;
#endif // ENABLE_DC
                }

                if (s || G_interrupt) {
                        bc_program_reset();
                        RETURN_STATUS(s);
                }

                // If the stack has changed, pointers may be invalid.
                ip = bc_vec_top(&G.prog.stack);
                func = bc_program_func(ip->func);
                code = func->code.v;
        }

        RETURN_STATUS(BC_STATUS_SUCCESS);
}
#if ERRORS_ARE_FATAL
# define zbc_program_exec(...) (zbc_program_exec(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

#if ENABLE_BC
static void bc_vm_info(void)
{
        printf("%s "BB_VER"\n"
                "Copyright (c) 2018 Gavin D. Howard and contributors\n"
        , applet_name);
}

static void bc_args(char **argv)
{
        unsigned opts;
        int i;

        GETOPT_RESET();
#if ENABLE_FEATURE_BC_LONG_OPTIONS
        opts = option_mask32 |= getopt32long(argv, "wvsqli",
                "warn\0"              No_argument "w"
                "version\0"           No_argument "v"
                "standard\0"          No_argument "s"
                "quiet\0"             No_argument "q"
                "mathlib\0"           No_argument "l"
                "interactive\0"       No_argument "i"
        );
#else
        opts = option_mask32 |= getopt32(argv, "wvsqli");
#endif
        if (getenv("POSIXLY_CORRECT"))
                option_mask32 |= BC_FLAG_S;

        if (opts & BC_FLAG_V) {
                bc_vm_info();
                exit(0);
        }

        for (i = optind; argv[i]; ++i)
                bc_vec_push(&G.files, argv + i);
}

static void bc_vm_envArgs(void)
{
        BcVec v;
        char *buf;
        char *env_args = getenv("BC_ENV_ARGS");

        if (!env_args) return;

        G.env_args = xstrdup(env_args);
        buf = G.env_args;

        bc_vec_init(&v, sizeof(char *), NULL);

        while (*(buf = skip_whitespace(buf)) != '\0') {
                bc_vec_push(&v, &buf);
                buf = skip_non_whitespace(buf);
                if (!*buf)
                        break;
                *buf++ = '\0';
        }

        // NULL terminate, and pass argv[] so that first arg is argv[1]
        if (sizeof(int) == sizeof(char*)) {
                bc_vec_push(&v, &const_int_0);
        } else {
                static char *const nullptr = NULL;
                bc_vec_push(&v, &nullptr);
        }
        bc_args(((char **)v.v) - 1);

        bc_vec_free(&v);
}
#endif // ENABLE_BC

static unsigned bc_vm_envLen(const char *var)
{
        char *lenv;
        unsigned len;

        lenv = getenv(var);
        len = BC_NUM_PRINT_WIDTH;
        if (!lenv) return len;

        len = bb_strtou(lenv, NULL, 10) - 1;
        if (errno || len < 2 || len >= INT_MAX)
                len = BC_NUM_PRINT_WIDTH;

        return len;
}

static BC_STATUS zbc_vm_process(const char *text)
{
        BcStatus s = zbc_parse_text(&G.prs, text);

        if (s) RETURN_STATUS(s);

        while (G.prs.l.t.t != BC_LEX_EOF) {
                ERROR_RETURN(s =) zcommon_parse(&G.prs);
                if (s) RETURN_STATUS(s);
        }

        if (BC_PARSE_CAN_EXEC(&G.prs)) {
                s = zbc_program_exec();
                fflush_and_check();
                if (s)
                        bc_program_reset();
        }

        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_vm_process(...) (zbc_vm_process(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_vm_file(const char *file)
{
        const char *sv_file;
        char *data;
        BcStatus s;
        BcFunc *main_func;
        BcInstPtr *ip;

        data = bc_read_file(file);
        if (!data) RETURN_STATUS(bc_error_fmt("file '%s' is not text", file));

        sv_file = G.prog.file;
        G.prog.file = file;
        bc_lex_file(&G.prs.l);
        s = zbc_vm_process(data);
        if (s) goto err;

        main_func = bc_program_func(BC_PROG_MAIN);
        ip = bc_vec_item(&G.prog.stack, 0);

        if (main_func->code.len < ip->idx)
                s = bc_error_fmt("file '%s' is not executable", file);

err:
        G.prog.file = sv_file;
        free(data);
        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_vm_file(...) (zbc_vm_file(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

static BC_STATUS zbc_vm_stdin(void)
{
        BcStatus s;
        BcVec buf, buffer;
        size_t str;
        bool comment;

        G.prog.file = NULL;
        bc_lex_file(&G.prs.l);

        bc_char_vec_init(&buffer);
        bc_char_vec_init(&buf);
        bc_vec_pushZeroByte(&buffer);

        // This loop is complex because the vm tries not to send any lines that end
        // with a backslash to the parser. The reason for that is because the parser
        // treats a backslash+newline combo as whitespace, per the bc spec. In that
        // case, and for strings and comments, the parser will expect more stuff.
        s = BC_STATUS_SUCCESS;
        comment = false;
        str = 0;
        for (;;) {
                size_t len;
                char *string;

                bc_read_line(&buf);
                len = buf.len - 1;
                if (len == 0) // "" buf means EOF
                        break;
                string = buf.v;
                if (len == 1) {
                        if (str && buf.v[0] == G.send)
                                str -= 1;
                        else if (buf.v[0] == G.sbgn)
                                str += 1;
                } else {
                        while (*string) {
                                char c = *string;
                                if (string != buf.v && string[-1] != '\\') {
                                        // checking applet type is cheaper than accessing sbgn/send
                                        if (IS_DC) // dc: sbgn = send = '"'
                                                str ^= (c == '"');
                                        else { // bc: sbgn = '[', send = ']'
                                                if (c == ']')
                                                        str -= 1;
                                                else if (c == '[')
                                                        str += 1;
                                        }
                                }
                                string++;
                                if (c == '/' && *string == '*') {
                                        comment = true;
                                        break;
                                }
                                if (c == '*' && *string == '/')
                                        comment = false;
                        }
                        if (str || comment || string[-2] == '\\') {
                                bc_vec_concat(&buffer, buf.v);
                                continue;
                        }
                }

                bc_vec_concat(&buffer, buf.v);
                s = zbc_vm_process(buffer.v);
                if (s) {
                        if (ENABLE_FEATURE_CLEAN_UP && !G_ttyin) {
                                // Debug config, non-interactive mode:
                                // return all the way back to main.
                                // Non-debug builds do not come here, they exit.
                                break;
                        }
                }

                bc_vec_pop_all(&buffer);
        }

        if (str) {
                s = bc_error("string end could not be found");
        }
        else if (comment) {
                s = bc_error("comment end could not be found");
        }

        bc_vec_free(&buf);
        bc_vec_free(&buffer);
        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_vm_stdin(...) (zbc_vm_stdin(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

#if ENABLE_BC
static const char bc_lib[] = {
        "scale=20"
"\n"    "define e(x){"
"\n"            "auto b,s,n,r,d,i,p,f,v"
"\n"            "b=ibase"
"\n"            "ibase=A"
"\n"            "if(x<0){"
"\n"                    "n=1"
"\n"                    "x=-x"
"\n"            "}"
"\n"            "s=scale"
"\n"            "r=6+s+0.44*x"
"\n"            "scale=scale(x)+1"
"\n"            "while(x>1){"
"\n"                    "d+=1"
"\n"                    "x/=2"
"\n"                    "scale+=1"
"\n"            "}"
"\n"            "scale=r"
"\n"            "r=x+1"
"\n"            "p=x"
"\n"            "f=v=1"
"\n"            "for(i=2;v!=0;++i){"
"\n"                    "p*=x"
"\n"                    "f*=i"
"\n"                    "v=p/f"
"\n"                    "r+=v"
"\n"            "}"
"\n"            "while((d--)!=0)r*=r"
"\n"            "scale=s"
"\n"            "ibase=b"
"\n"            "if(n!=0)return(1/r)"
"\n"            "return(r/1)"
"\n"    "}"
"\n"    "define l(x){"
"\n"            "auto b,s,r,p,a,q,i,v"
"\n"            "b=ibase"
"\n"            "ibase=A"
"\n"            "if(x<=0){"
"\n"                    "r=(1-10^scale)/1"
"\n"                    "ibase=b"
"\n"                    "return(r)"
"\n"            "}"
"\n"            "s=scale"
"\n"            "scale+=6"
"\n"            "p=2"
"\n"            "while(x>=2){"
"\n"                    "p*=2"
"\n"                    "x=sqrt(x)"
"\n"            "}"
"\n"            "while(x<=0.5){"
"\n"                    "p*=2"
"\n"                    "x=sqrt(x)"
"\n"            "}"
"\n"            "r=a=(x-1)/(x+1)"
"\n"            "q=a*a"
"\n"                    "v=1"
"\n"            "for(i=3;v!=0;i+=2){"
"\n"                    "a*=q"
"\n"                    "v=a/i"
"\n"                    "r+=v"
"\n"            "}"
"\n"            "r*=p"
"\n"            "scale=s"
"\n"            "ibase=b"
"\n"            "return(r/1)"
"\n"    "}"
"\n"    "define s(x){"
"\n"            "auto b,s,r,n,a,q,i"
"\n"            "b=ibase"
"\n"            "ibase=A"
"\n"            "s=scale"
"\n"            "scale=1.1*s+2"
"\n"            "a=a(1)"
"\n"            "if(x<0){"
"\n"                    "n=1"
"\n"                    "x=-x"
"\n"            "}"
"\n"            "scale=0"
"\n"            "q=(x/a+2)/4"
"\n"            "x=x-4*q*a"
"\n"            "if(q%2!=0)x=-x"
"\n"            "scale=s+2"
"\n"            "r=a=x"
"\n"            "q=-x*x"
"\n"            "for(i=3;a!=0;i+=2){"
"\n"                    "a*=q/(i*(i-1))"
"\n"                    "r+=a"
"\n"            "}"
"\n"            "scale=s"
"\n"            "ibase=b"
"\n"            "if(n!=0)return(-r/1)"
"\n"            "return(r/1)"
"\n"    "}"
"\n"    "define c(x){"
"\n"            "auto b,s"
"\n"            "b=ibase"
"\n"            "ibase=A"
"\n"            "s=scale"
"\n"            "scale*=1.2"
"\n"            "x=s(2*a(1)+x)"
"\n"            "scale=s"
"\n"            "ibase=b"
"\n"            "return(x/1)"
"\n"    "}"
"\n"    "define a(x){"
"\n"            "auto b,s,r,n,a,m,t,f,i,u"
"\n"            "b=ibase"
"\n"            "ibase=A"
"\n"            "n=1"
"\n"            "if(x<0){"
"\n"                    "n=-1"
"\n"                    "x=-x"
"\n"            "}"
"\n"            "if(x==1){"
"\n"                    "if(scale<65){"
"\n"                            "return(.7853981633974483096156608458198757210492923498437764552437361480/n)"
"\n"                    "}"
"\n"            "}"
"\n"            "if(x==.2){"
"\n"                    "if(scale<65){"
"\n"                            "return(.1973955598498807583700497651947902934475851037878521015176889402/n)"
"\n"                    "}"
"\n"            "}"
"\n"            "s=scale"
"\n"            "if(x>.2){"
"\n"                    "scale+=5"
"\n"                    "a=a(.2)"
"\n"            "}"
"\n"            "scale=s+3"
"\n"            "while(x>.2){"
"\n"                    "m+=1"
"\n"                    "x=(x-.2)/(1+.2*x)"
"\n"            "}"
"\n"            "r=u=x"
"\n"            "f=-x*x"
"\n"            "t=1"
"\n"            "for(i=3;t!=0;i+=2){"
"\n"                    "u*=f"
"\n"                    "t=u/i"
"\n"                    "r+=t"
"\n"            "}"
"\n"            "scale=s"
"\n"            "ibase=b"
"\n"            "return((m*a+r)/n)"
"\n"    "}"
"\n"    "define j(n,x){"
"\n"            "auto b,s,o,a,i,v,f"
"\n"            "b=ibase"
"\n"            "ibase=A"
"\n"            "s=scale"
"\n"            "scale=0"
"\n"            "n/=1"
"\n"            "if(n<0){"
"\n"                    "n=-n"
"\n"                    "if(n%2==1)o=1"
"\n"            "}"
"\n"            "a=1"
"\n"            "for(i=2;i<=n;++i)a*=i"
"\n"            "scale=1.5*s"
"\n"            "a=(x^n)/2^n/a"
"\n"            "r=v=1"
"\n"            "f=-x*x/4"
"\n"            "scale=scale+length(a)-scale(a)"
"\n"            "for(i=1;v!=0;++i){"
"\n"                    "v=v*f/i/(n+i)"
"\n"                    "r+=v"
"\n"            "}"
"\n"            "scale=s"
"\n"            "ibase=b"
"\n"            "if(o!=0)a=-a"
"\n"            "return(a*r/1)"
"\n"    "}"
};
#endif // ENABLE_BC

static BC_STATUS zbc_vm_exec(void)
{
        BcStatus s;
        size_t i;

#if ENABLE_BC
        if (option_mask32 & BC_FLAG_L) {

                // We know that internal library is not buggy,
                // thus error checking is normally disabled.
# define DEBUG_LIB 0
                bc_lex_file(&G.prs.l);
                s = zbc_parse_text(&G.prs, bc_lib);
                if (DEBUG_LIB && s) RETURN_STATUS(s);

                while (G.prs.l.t.t != BC_LEX_EOF) {
                        ERROR_RETURN(s =) zcommon_parse(&G.prs);
                        if (DEBUG_LIB && s) RETURN_STATUS(s);
                }
                s = zbc_program_exec();
                if (DEBUG_LIB && s) RETURN_STATUS(s);
        }
#endif

        s = BC_STATUS_SUCCESS;
        for (i = 0; !s && i < G.files.len; ++i)
                s = zbc_vm_file(*((char **) bc_vec_item(&G.files, i)));
        if (ENABLE_FEATURE_CLEAN_UP && s && !G_ttyin) {
                // Debug config, non-interactive mode:
                // return all the way back to main.
                // Non-debug builds do not come here, they exit.
                RETURN_STATUS(s);
        }

        if (IS_BC || (option_mask32 & BC_FLAG_I))
                s = zbc_vm_stdin();

        if (!s && !BC_PARSE_CAN_EXEC(&G.prs))
                s = zbc_vm_process("");

        RETURN_STATUS(s);
}
#if ERRORS_ARE_FATAL
# define zbc_vm_exec(...) (zbc_vm_exec(__VA_ARGS__), BC_STATUS_SUCCESS)
#endif

#if ENABLE_FEATURE_CLEAN_UP
static void bc_program_free(void)
{
        bc_num_free(&G.prog.ib);
        bc_num_free(&G.prog.ob);
        bc_num_free(&G.prog.hexb);
# if ENABLE_DC
        bc_num_free(&G.prog.strmb);
# endif
        bc_vec_free(&G.prog.fns);
        bc_vec_free(&G.prog.fn_map);
        bc_vec_free(&G.prog.vars);
        bc_vec_free(&G.prog.var_map);
        bc_vec_free(&G.prog.arrs);
        bc_vec_free(&G.prog.arr_map);
        bc_vec_free(&G.prog.strs);
        bc_vec_free(&G.prog.consts);
        bc_vec_free(&G.prog.results);
        bc_vec_free(&G.prog.stack);
        bc_num_free(&G.prog.last);
        bc_num_free(&G.prog.zero);
        bc_num_free(&G.prog.one);
}

static void bc_vm_free(void)
{
        bc_vec_free(&G.files);
        bc_program_free();
        bc_parse_free(&G.prs);
        free(G.env_args);
}
#endif

static void bc_program_init(void)
{
        size_t idx;
        BcInstPtr ip;

        /* memset(&G.prog, 0, sizeof(G.prog)); - already is */
        memset(&ip, 0, sizeof(BcInstPtr));

        /* G.prog.nchars = G.prog.scale = 0; - already is */
        bc_num_init_DEF_SIZE(&G.prog.ib);
        bc_num_ten(&G.prog.ib);
        G.prog.ib_t = 10;

        bc_num_init_DEF_SIZE(&G.prog.ob);
        bc_num_ten(&G.prog.ob);
        G.prog.ob_t = 10;

        bc_num_init_DEF_SIZE(&G.prog.hexb);
        bc_num_ten(&G.prog.hexb);
        G.prog.hexb.num[0] = 6;

#if ENABLE_DC
        bc_num_init_DEF_SIZE(&G.prog.strmb);
        bc_num_ulong2num(&G.prog.strmb, UCHAR_MAX + 1);
#endif

        bc_num_init_DEF_SIZE(&G.prog.last);
        //bc_num_zero(&G.prog.last); - already is

        bc_num_init_DEF_SIZE(&G.prog.zero);
        //bc_num_zero(&G.prog.zero); - already is

        bc_num_init_DEF_SIZE(&G.prog.one);
        bc_num_one(&G.prog.one);

        bc_vec_init(&G.prog.fns, sizeof(BcFunc), bc_func_free);
        bc_vec_init(&G.prog.fn_map, sizeof(BcId), bc_id_free);

        bc_program_addFunc(xstrdup("(main)"), &idx);
        bc_program_addFunc(xstrdup("(read)"), &idx);

        bc_vec_init(&G.prog.vars, sizeof(BcVec), bc_vec_free);
        bc_vec_init(&G.prog.var_map, sizeof(BcId), bc_id_free);

        bc_vec_init(&G.prog.arrs, sizeof(BcVec), bc_vec_free);
        bc_vec_init(&G.prog.arr_map, sizeof(BcId), bc_id_free);

        bc_vec_init(&G.prog.strs, sizeof(char *), bc_string_free);
        bc_vec_init(&G.prog.consts, sizeof(char *), bc_string_free);
        bc_vec_init(&G.prog.results, sizeof(BcResult), bc_result_free);
        bc_vec_init(&G.prog.stack, sizeof(BcInstPtr), NULL);
        bc_vec_push(&G.prog.stack, &ip);
}

static int bc_vm_init(const char *env_len)
{
#if ENABLE_FEATURE_EDITING
        G.line_input_state = new_line_input_t(DO_HISTORY);
#endif
        G.prog.len = bc_vm_envLen(env_len);

        bc_vec_init(&G.files, sizeof(char *), NULL);
        if (IS_BC)
                IF_BC(bc_vm_envArgs();)
        bc_program_init();
        bc_parse_create(&G.prs, BC_PROG_MAIN);

//TODO: in GNU bc, the check is (isatty(0) && isatty(1)),
//-i option unconditionally enables this regardless of isatty():
        if (isatty(0)) {
#if ENABLE_FEATURE_BC_SIGNALS
                G_ttyin = 1;
                // With SA_RESTART, most system calls will restart
                // (IOW: they won't fail with EINTR).
                // In particular, this means ^C won't cause
                // stdout to get into "error state" if SIGINT hits
                // within write() syscall.
                //
                // The downside is that ^C while tty input is taken
                // will only be handled after [Enter] since read()
                // from stdin is not interrupted by ^C either,
                // it restarts, thus fgetc() does not return on ^C.
                // (This problem manifests only if line editing is disabled)
                signal_SA_RESTART_empty_mask(SIGINT, record_signo);

                // Without SA_RESTART, this exhibits a bug:
                // "while (1) print 1" and try ^C-ing it.
                // Intermittently, instead of returning to input line,
                // you'll get "output error: Interrupted system call"
                // and exit.
                //signal_no_SA_RESTART_empty_mask(SIGINT, record_signo);
#endif
                return 1; // "tty"
        }
        return 0; // "not a tty"
}

static BcStatus bc_vm_run(void)
{
        BcStatus st = zbc_vm_exec();
#if ENABLE_FEATURE_CLEAN_UP
        if (G_exiting) // it was actually "halt" or "quit"
                st = EXIT_SUCCESS;
        bc_vm_free();
# if ENABLE_FEATURE_EDITING
        free_line_input_t(G.line_input_state);
# endif
        FREE_G();
#endif
        return st;
}

#if ENABLE_BC
int bc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int bc_main(int argc UNUSED_PARAM, char **argv)
{
        int is_tty;

        INIT_G();
        G.sbgn = G.send = '"';

        is_tty = bc_vm_init("BC_LINE_LENGTH");

        bc_args(argv);

        if (is_tty && !(option_mask32 & BC_FLAG_Q))
                bc_vm_info();

        return bc_vm_run();
}
#endif

#if ENABLE_DC
int dc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int dc_main(int argc UNUSED_PARAM, char **argv)
{
        int noscript;

        INIT_G();
        G.sbgn = '[';
        G.send = ']';
        /*
         * TODO: dc (GNU bc 1.07.1) 1.4.1 seems to use width
         * 1 char wider than bc from the same package.
         * Both default width, and xC_LINE_LENGTH=N are wider:
         * "DC_LINE_LENGTH=5 dc -e'123456 p'" prints:
         *      1234\
         *      56
         * "echo '123456' | BC_LINE_LENGTH=5 bc" prints:
         *      123\
         *      456
         * Do the same, or it's a bug?
         */
        bc_vm_init("DC_LINE_LENGTH");

        // Run -e'SCRIPT' and -fFILE in order of appearance, then handle FILEs
        noscript = BC_FLAG_I;
        for (;;) {
                int n = getopt(argc, argv, "e:f:x");
                if (n <= 0)
                        break;
                switch (n) {
                case 'e':
                        noscript = 0;
                        n = zbc_vm_process(optarg);
                        if (n) return n;
                        break;
                case 'f':
                        noscript = 0;
                        n = zbc_vm_file(optarg);
                        if (n) return n;
                        break;
                case 'x':
                        option_mask32 |= DC_FLAG_X;
                        break;
                default:
                        bb_show_usage();
                }
        }
        argv += optind;

        while (*argv) {
                noscript = 0;
                bc_vec_push(&G.files, argv++);
        }

        option_mask32 |= noscript; // set BC_FLAG_I if we need to interpret stdin

        return bc_vm_run();
}
#endif

#endif // not DC_SMALL