Update internal.h to conditionally include asm/string.h

[oweals/busybox.git] / math.c

diff --git a/math.c b/math.c
index 5c1560a4eb3c91602f7e328bfa30c5533af6105b..eb8f331fdb96705bc520eaaad6e9aa69318a2f49 100644 (file)
--- a/math.c
+++ b/math.c
@@ -1,4 +1,6 @@
+/* vi: set sw=4 ts=4: */
 #include "internal.h"
+#include <ctype.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
@@ -6,128 +8,122 @@
 
 /* Tiny RPN calculator, because "expr" didn't give me bitwise operations. */
 
-const char                     math_usage[] = "math expression ...";
+static const char math_usage[] = "math expression ...\n"
+#ifndef BB_FEATURE_TRIVIAL_HELP
+               "\nThis is a Tiny RPN calculator that understands the\n"
+               "following operations: +, -, /, *, and, or, not, eor.\n"
+               "i.e. 'math 2 2 add' -> 4, and 'math 8 8 \\* 2 2 + /' -> 16\n"
+#endif
+               ;
 
-static double          stack[100];
-static unsigned int    pointer;
+static double stack[100];
+static unsigned int pointer;
 
-static void
-push(double a)
+static void push(double a)
 {
-       if ( pointer >= (sizeof(stack) / sizeof(*stack)) ) {
+       if (pointer >= (sizeof(stack) / sizeof(*stack))) {
                fprintf(stderr, "math: stack overflow\n");
                exit(-1);
-       }
-       else
+       } else
                stack[pointer++] = a;
 }
 
-static double
-pop()
+static double pop()
 {
-       if ( pointer == 0 ) {
+       if (pointer == 0) {
                fprintf(stderr, "math: stack underflow\n");
                exit(-1);
        }
        return stack[--pointer];
 }
 
-static void
-add()
+static void add()
 {
        push(pop() + pop());
 }
 
-static void
-sub()
+static void sub()
 {
-       double  subtrahend = pop();
+       double subtrahend = pop();
 
        push(pop() - subtrahend);
 }
 
-static void
-mul()
+static void mul()
 {
        push(pop() * pop());
 }
 
-static void
-divide()
+static void divide()
 {
-       double  divisor = pop();
+       double divisor = pop();
+
        push(pop() / divisor);
 }
 
-static void
-and()
+static void and()
 {
-       push((unsigned int)pop() & (unsigned int)pop());
+       push((unsigned int) pop() & (unsigned int) pop());
 }
 
-static void
-or()
+static void or()
 {
-       push((unsigned int)pop() | (unsigned int)pop());
+       push((unsigned int) pop() | (unsigned int) pop());
 }
 
-static void
-eor()
+static void eor()
 {
-       push((unsigned int)pop() ^ (unsigned int)pop());
+       push((unsigned int) pop() ^ (unsigned int) pop());
 }
 
-static void
-not()
+static void not()
 {
-       push(~(unsigned int)pop());
+       push(~(unsigned int) pop());
 }
 
-static void
-print()
+static void print()
 {
        printf("%g\n", pop());
 }
 
 struct op {
-       const char *    name;
-       void                    (*function)();
+       const char *name;
+       void (*function) ();
 };
 
-static const struct op operators[] = {
-       {       "add",  add     },
-       {       "and",  and     },
-       {       "div",  divide  },
-       {       "eor",  eor     },
-       {       "mul",  mul     },
-       {       "not",  not     },
-       {       "or",   or      },
-       {       "sub",  sub     },
-       {       0,              0       }
+static const struct op operators[] = {
+       {"+", add},
+       {"-", sub},
+       {"*", mul},
+       {"/", divide},
+       {"and", and},
+       {"or", or},
+       {"not", not},
+       {"eor", eor},
+       {0, 0}
 };
 
-static void
-stack_machine(const char * argument)
+static void stack_machine(const char *argument)
 {
-       char *                          endPointer = 0;
-       double                          d;
-       const struct op *       o = operators;
+       char *endPointer = 0;
+       double d;
+       const struct op *o = operators;
 
-       if ( argument == 0 ) {
+       if (argument == 0) {
                print();
                return;
        }
 
        d = strtod(argument, &endPointer);
 
-       if ( endPointer != argument ) {
+       if (endPointer != argument) {
                push(d);
                return;
        }
 
-       while ( o->name != 0 ) {
-               if ( strcmp(o->name, argument) == 0 ) {
-                       (*(o->function))();
+       while (o->name != 0) {
+               if (strcmp(o->name, argument) == 0) {
+                       (*(o->function)) ();
                        return;
                }
                o++;
@@ -136,14 +132,59 @@ stack_machine(const char * argument)
        exit(-1);
 }
 
-int
-math_main(struct FileInfo * i, int argc, char * * argv)
+/* return pointer to next token in buffer and set *buffer to one char
+ * past the end of the above mentioned token 
+ */
+static char *get_token(char **buffer)
+{
+       char *start   = NULL;
+       char *current = *buffer;
+
+       while (isspace(*current)) { current++; }
+       if (*current != 0) {
+               start = current;
+               while (!isspace(*current) && current != 0) { current++; }
+               *buffer = current;
+       }
+       return start;
+}
+
+/* In Perl one might say, scalar m|\s*(\S+)\s*|g */
+static int number_of_tokens(char *buffer)
 {
-       while ( argc >= 2 ) {
-               stack_machine(argv[1]);
-               argv++;
-               argc--;
+       int   i = 0;
+       char *b = buffer;
+       while (get_token(&b)) { i++; }
+       return i;
+}
+
+int math_main(int argc, char **argv)
+{
+       /* take stuff from stdin if no args are given */
+       if (argc <= 1) {
+               int i, len;
+               char *line   = NULL;
+               char *cursor = NULL;
+               char *token  = NULL;
+               while ((line = cstring_lineFromFile(stdin))) {
+                       cursor = line;
+                       len = number_of_tokens(line);
+                       for (i = 0; i < len; i++) {
+                               token = get_token(&cursor);
+                               *cursor++ = 0;
+                               stack_machine(token);
+                       }
+                       free(line);
+               }
+       } else {
+               if (*argv[1]=='-')
+                       usage(math_usage);
+               while (argc >= 2) {
+                       stack_machine(argv[1]);
+                       argv++;
+                       argc--;
+               }
        }
        stack_machine(0);
-       return 0;
+       return( TRUE);
 }