[oweals/busybox.git] / gzip.c

/* gzip.c -- this is a stripped down version of gzip I put into busybox, it does
 * only standard in to standard out with -9 compression.  It also requires the
 * zcat module for some important functions.  
 *
 * Charles P. Wright <cpw@unix.asb.com>
 */
#include "internal.h"
#ifdef BB_GZIP

#ifndef BB_ZCAT
#error you need zcat to have gzip support!
#endif

const char gzip_usage[] = "gzip\nignores all command line arguments\ncompress stdin to stdout with -9 compression\n";

/* gzip.h -- common declarations for all gzip modules
 * Copyright (C) 1992-1993 Jean-loup Gailly.
 * This is free software; you can redistribute it and/or modify it under the
 * terms of the GNU General Public License, see the file COPYING.
 */

#if defined(__STDC__) || defined(PROTO)
#  define OF(args)  args
#else
#  define OF(args)  ()
#endif

#ifdef __STDC__
   typedef void *voidp;
#else
   typedef char *voidp;
#endif

/* I don't like nested includes, but the string and io functions are used
 * too often
 */
#include <stdio.h>
#if !defined(NO_STRING_H) || defined(STDC_HEADERS)
#  include <string.h>
#  if !defined(STDC_HEADERS) && !defined(NO_MEMORY_H) && !defined(__GNUC__)
#    include <memory.h>
#  endif
#  define memzero(s, n)     memset ((voidp)(s), 0, (n))
#else
#  include <strings.h>
#  define strchr            index 
#  define strrchr           rindex
#  define memcpy(d, s, n)   bcopy((s), (d), (n)) 
#  define memcmp(s1, s2, n) bcmp((s1), (s2), (n)) 
#  define memzero(s, n)     bzero((s), (n))
#endif

#ifndef RETSIGTYPE
#  define RETSIGTYPE void
#endif

#define local static

typedef unsigned char  uch;
typedef unsigned short ush;
typedef unsigned long  ulg;

/* Return codes from gzip */
#define OK      0
#define ERROR   1
#define WARNING 2

/* Compression methods (see algorithm.doc) */
#define STORED      0
#define COMPRESSED  1
#define PACKED      2
#define LZHED       3
/* methods 4 to 7 reserved */
#define DEFLATED    8
#define MAX_METHODS 9
extern int method;         /* compression method */

/* To save memory for 16 bit systems, some arrays are overlaid between
 * the various modules:
 * deflate:  prev+head   window      d_buf  l_buf  outbuf
 * unlzw:    tab_prefix  tab_suffix  stack  inbuf  outbuf
 * inflate:              window             inbuf
 * unpack:               window             inbuf  prefix_len
 * unlzh:    left+right  window      c_table inbuf c_len
 * For compression, input is done in window[]. For decompression, output
 * is done in window except for unlzw.
 */

#ifndef INBUFSIZ
#  ifdef SMALL_MEM
#    define INBUFSIZ  0x2000  /* input buffer size */
#  else
#    define INBUFSIZ  0x8000  /* input buffer size */
#  endif
#endif
#define INBUF_EXTRA  64     /* required by unlzw() */

#ifndef OUTBUFSIZ
#  ifdef SMALL_MEM
#    define OUTBUFSIZ   8192  /* output buffer size */
#  else
#    define OUTBUFSIZ  16384  /* output buffer size */
#  endif
#endif
#define OUTBUF_EXTRA 2048   /* required by unlzw() */

#ifndef DIST_BUFSIZE
#  ifdef SMALL_MEM
#    define DIST_BUFSIZE 0x2000 /* buffer for distances, see trees.c */
#  else
#    define DIST_BUFSIZE 0x8000 /* buffer for distances, see trees.c */
#  endif
#endif

#ifdef DYN_ALLOC
#  define EXTERN(type, array)  extern type * near array
#  define DECLARE(type, array, size)  type * near array
#  define ALLOC(type, array, size) { \
      array = (type*)fcalloc((size_t)(((size)+1L)/2), 2*sizeof(type)); \
      if (array == NULL) error("insufficient memory"); \
   }
#  define FREE(array) {if (array != NULL) fcfree(array), array=NULL;}
#else
#  define EXTERN(type, array)  extern type array[]
#  define DECLARE(type, array, size)  type array[size]
#  define ALLOC(type, array, size)
#  define FREE(array)
#endif

EXTERN(uch, inbuf);          /* input buffer */
EXTERN(uch, outbuf);         /* output buffer */
EXTERN(ush, d_buf);          /* buffer for distances, see trees.c */
EXTERN(uch, window);         /* Sliding window and suffix table (unlzw) */
#define tab_suffix window
#ifndef MAXSEG_64K
#  define tab_prefix prev    /* hash link (see deflate.c) */
#  define head (prev+WSIZE)  /* hash head (see deflate.c) */
   EXTERN(ush, tab_prefix);  /* prefix code (see unlzw.c) */
#else
#  define tab_prefix0 prev
#  define head tab_prefix1
   EXTERN(ush, tab_prefix0); /* prefix for even codes */
   EXTERN(ush, tab_prefix1); /* prefix for odd  codes */
#endif

extern unsigned insize; /* valid bytes in inbuf */
extern unsigned inptr;  /* index of next byte to be processed in inbuf */
extern unsigned outcnt; /* bytes in output buffer */

extern long bytes_in;   /* number of input bytes */
extern long bytes_out;  /* number of output bytes */
extern long header_bytes;/* number of bytes in gzip header */

#define isize bytes_in
/* for compatibility with old zip sources (to be cleaned) */

extern int  ifd;        /* input file descriptor */
extern int  ofd;        /* output file descriptor */
extern char ifname[];   /* input file name or "stdin" */
extern char ofname[];   /* output file name or "stdout" */
extern char *progname;  /* program name */

extern long time_stamp; /* original time stamp (modification time) */
extern long ifile_size; /* input file size, -1 for devices (debug only) */

typedef int file_t;     /* Do not use stdio */
#define NO_FILE  (-1)   /* in memory compression */


#define PACK_MAGIC     "\037\036" /* Magic header for packed files */
#define GZIP_MAGIC     "\037\213" /* Magic header for gzip files, 1F 8B */
#define OLD_GZIP_MAGIC "\037\236" /* Magic header for gzip 0.5 = freeze 1.x */
#define LZH_MAGIC      "\037\240" /* Magic header for SCO LZH Compress files*/
#define PKZIP_MAGIC    "\120\113\003\004" /* Magic header for pkzip files */

/* gzip flag byte */
#define ASCII_FLAG   0x01 /* bit 0 set: file probably ascii text */
#define CONTINUATION 0x02 /* bit 1 set: continuation of multi-part gzip file */
#define EXTRA_FIELD  0x04 /* bit 2 set: extra field present */
#define ORIG_NAME    0x08 /* bit 3 set: original file name present */
#define COMMENT      0x10 /* bit 4 set: file comment present */
#define ENCRYPTED    0x20 /* bit 5 set: file is encrypted */
#define RESERVED     0xC0 /* bit 6,7:   reserved */

/* internal file attribute */
#define UNKNOWN 0xffff
#define BINARY  0
#define ASCII   1

#ifndef WSIZE
#  define WSIZE 0x8000     /* window size--must be a power of two, and */
#endif                     /*  at least 32K for zip's deflate method */

#define MIN_MATCH  3
#define MAX_MATCH  258
/* The minimum and maximum match lengths */

#define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
/* Minimum amount of lookahead, except at the end of the input file.
 * See deflate.c for comments about the MIN_MATCH+1.
 */

#define MAX_DIST  (WSIZE-MIN_LOOKAHEAD)
/* In order to simplify the code, particularly on 16 bit machines, match
 * distances are limited to MAX_DIST instead of WSIZE.
 */

extern int decrypt;        /* flag to turn on decryption */
extern int exit_code;      /* program exit code */
extern int verbose;        /* be verbose (-v) */
extern int quiet;          /* be quiet (-q) */
extern int test;           /* check .z file integrity */
extern int to_stdout;      /* output to stdout (-c) */
extern int save_orig_name; /* set if original name must be saved */

#define get_byte()  (inptr < insize ? inbuf[inptr++] : fill_inbuf(0))
#define try_byte()  (inptr < insize ? inbuf[inptr++] : fill_inbuf(1))

/* put_byte is used for the compressed output, put_ubyte for the
 * uncompressed output. However unlzw() uses window for its
 * suffix table instead of its output buffer, so it does not use put_ubyte
 * (to be cleaned up).
 */
#define put_byte(c) {outbuf[outcnt++]=(uch)(c); if (outcnt==OUTBUFSIZ)\
   flush_outbuf();}
#define put_ubyte(c) {window[outcnt++]=(uch)(c); if (outcnt==WSIZE)\
   flush_window();}

/* Output a 16 bit value, lsb first */
#define put_short(w) \
{ if (outcnt < OUTBUFSIZ-2) { \
    outbuf[outcnt++] = (uch) ((w) & 0xff); \
    outbuf[outcnt++] = (uch) ((ush)(w) >> 8); \
  } else { \
    put_byte((uch)((w) & 0xff)); \
    put_byte((uch)((ush)(w) >> 8)); \
  } \
}

/* Output a 32 bit value to the bit stream, lsb first */
#define put_long(n) { \
    put_short((n) & 0xffff); \
    put_short(((ulg)(n)) >> 16); \
}

#define seekable()    0  /* force sequential output */
#define translate_eol 0  /* no option -a yet */

#define tolow(c)  (isupper(c) ? (c)-'A'+'a' : (c))    /* force to lower case */

/* Macros for getting two-byte and four-byte header values */
#define SH(p) ((ush)(uch)((p)[0]) | ((ush)(uch)((p)[1]) << 8))
#define LG(p) ((ulg)(SH(p)) | ((ulg)(SH((p)+2)) << 16))

/* Diagnostic functions */
#ifdef DEBUG
#  define Assert(cond,msg) {if(!(cond)) error(msg);}
#  define Trace(x) fprintf x
#  define Tracev(x) {if (verbose) fprintf x ;}
#  define Tracevv(x) {if (verbose>1) fprintf x ;}
#  define Tracec(c,x) {if (verbose && (c)) fprintf x ;}
#  define Tracecv(c,x) {if (verbose>1 && (c)) fprintf x ;}
#else
#  define Assert(cond,msg)
#  define Trace(x)
#  define Tracev(x)
#  define Tracevv(x)
#  define Tracec(c,x)
#  define Tracecv(c,x)
#endif

#define WARN(msg) {if (!quiet) fprintf msg ; \
                   if (exit_code == OK) exit_code = WARNING;}

local void do_exit(int exitcode);

        /* in zip.c: */
extern int zip        OF((int in, int out));
extern int file_read  OF((char *buf,  unsigned size));

        /* in unzip.c */
extern int unzip      OF((int in, int out));
extern int check_zipfile OF((int in));

        /* in unpack.c */
extern int unpack     OF((int in, int out));

        /* in unlzh.c */
extern int unlzh      OF((int in, int out));

        /* in gzip.c */
RETSIGTYPE abort_gzip OF((void));

        /* in deflate.c */
void lm_init OF((ush *flags));
ulg  deflate OF((void));

        /* in trees.c */
void ct_init     OF((ush *attr, int *method));
int  ct_tally    OF((int dist, int lc));
ulg  flush_block OF((char *buf, ulg stored_len, int eof));

        /* in bits.c */
void     bi_init    OF((file_t zipfile));
void     send_bits  OF((int value, int length));
unsigned bi_reverse OF((unsigned value, int length));
void     bi_windup  OF((void));
void     copy_block OF((char *buf, unsigned len, int header));
extern   int (*read_buf) OF((char *buf, unsigned size));

        /* in util.c: */
extern int copy           OF((int in, int out));
extern ulg  updcrc        OF((uch *s, unsigned n));
extern void clear_bufs    OF((void));
extern int  fill_inbuf    OF((int eof_ok));
extern void flush_outbuf  OF((void));
extern void flush_window  OF((void));
extern void write_buf     OF((int fd, voidp buf, unsigned cnt));
extern char *strlwr       OF((char *s));
extern char *add_envopt   OF((int *argcp, char ***argvp, char *env));
extern void error         OF((char *m));
extern void warn          OF((char *a, char *b));
extern void read_error    OF((void));
extern void write_error   OF((void));
extern void display_ratio OF((long num, long den, FILE *file));
extern voidp xmalloc      OF((unsigned int size));

        /* in inflate.c */
extern int inflate OF((void));
/* lzw.h -- define the lzw functions.
 * Copyright (C) 1992-1993 Jean-loup Gailly.
 * This is free software; you can redistribute it and/or modify it under the
 * terms of the GNU General Public License, see the file COPYING.
 */

#if !defined(OF) && defined(lint)
#  include "gzip.h"
#endif

#ifndef BITS
#  define BITS 16
#endif
#define INIT_BITS 9              /* Initial number of bits per code */

#define BIT_MASK    0x1f /* Mask for 'number of compression bits' */
/* Mask 0x20 is reserved to mean a fourth header byte, and 0x40 is free.
 * It's a pity that old uncompress does not check bit 0x20. That makes
 * extension of the format actually undesirable because old compress
 * would just crash on the new format instead of giving a meaningful
 * error message. It does check the number of bits, but it's more
 * helpful to say "unsupported format, get a new version" than
 * "can only handle 16 bits".
 */

#define BLOCK_MODE  0x80
/* Block compression: if table is full and compression rate is dropping,
 * clear the dictionary.
 */

#define LZW_RESERVED 0x60 /* reserved bits */

#define CLEAR  256       /* flush the dictionary */
#define FIRST  (CLEAR+1) /* first free entry */

extern int maxbits;      /* max bits per code for LZW */
extern int block_mode;   /* block compress mode -C compatible with 2.0 */

/* revision.h -- define the version number
 * Copyright (C) 1992-1993 Jean-loup Gailly.
 * This is free software; you can redistribute it and/or modify it under the
 * terms of the GNU General Public License, see the file COPYING.
 */

#define VERSION "1.2.4"
#define PATCHLEVEL 0
#define REVDATE "18 Aug 93"

/* This version does not support compression into old compress format: */
#ifdef LZW
#  undef LZW
#endif

/* $Id: gzip.c,v 1.3 1999/10/16 15:48:40 andersen Exp $ */
/* tailor.h -- target dependent definitions
 * Copyright (C) 1992-1993 Jean-loup Gailly.
 * This is free software; you can redistribute it and/or modify it under the
 * terms of the GNU General Public License, see the file COPYING.
 */

/* The target dependent definitions should be defined here only.
 * The target dependent functions should be defined in tailor.c.
 */

/* $Id: gzip.c,v 1.3 1999/10/16 15:48:40 andersen Exp $ */

#if defined(__MSDOS__) && !defined(MSDOS)
#  define MSDOS
#endif

#if defined(__OS2__) && !defined(OS2)
#  define OS2
#endif

#if defined(OS2) && defined(MSDOS) /* MS C under OS/2 */
#  undef MSDOS
#endif

#ifdef MSDOS
#  ifdef __GNUC__
     /* DJGPP version 1.09+ on MS-DOS.
      * The DJGPP 1.09 stat() function must be upgraded before gzip will
      * fully work.
      * No need for DIRENT, since <unistd.h> defines POSIX_SOURCE which
      * implies DIRENT.
      */
#    define near
#  else
#    define MAXSEG_64K
#    ifdef __TURBOC__
#      define NO_OFF_T
#      ifdef __BORLANDC__
#        define DIRENT
#      else
#        define NO_UTIME
#      endif
#    else /* MSC */
#      define HAVE_SYS_UTIME_H
#      define NO_UTIME_H
#    endif
#  endif
#  define PATH_SEP2 '\\'
#  define PATH_SEP3 ':'
#  define MAX_PATH_LEN  128
#  define NO_MULTIPLE_DOTS
#  define MAX_EXT_CHARS 3
#  define Z_SUFFIX "z"
#  define NO_CHOWN
#  define PROTO
#  define STDC_HEADERS
#  define NO_SIZE_CHECK
#  define casemap(c) tolow(c) /* Force file names to lower case */
#  include <io.h>
#  define OS_CODE  0x00
#  define SET_BINARY_MODE(fd) setmode(fd, O_BINARY)
#  if !defined(NO_ASM) && !defined(ASMV)
#    define ASMV
#  endif
#else
#  define near
#endif

#ifdef OS2
#  define PATH_SEP2 '\\'
#  define PATH_SEP3 ':'
#  define MAX_PATH_LEN  260
#  ifdef OS2FAT
#    define NO_MULTIPLE_DOTS
#    define MAX_EXT_CHARS 3
#    define Z_SUFFIX "z"
#    define casemap(c) tolow(c)
#  endif
#  define NO_CHOWN
#  define PROTO
#  define STDC_HEADERS
#  include <io.h>
#  define OS_CODE  0x06
#  define SET_BINARY_MODE(fd) setmode(fd, O_BINARY)
#  ifdef _MSC_VER
#    define HAVE_SYS_UTIME_H
#    define NO_UTIME_H
#    define MAXSEG_64K
#    undef near
#    define near _near
#  endif
#  ifdef __EMX__
#    define HAVE_SYS_UTIME_H
#    define NO_UTIME_H
#    define DIRENT
#    define EXPAND(argc,argv) \
       {_response(&argc, &argv); _wildcard(&argc, &argv);}
#  endif
#  ifdef __BORLANDC__
#    define DIRENT
#  endif
#  ifdef __ZTC__
#    define NO_DIR
#    define NO_UTIME_H
#    include <dos.h>
#    define EXPAND(argc,argv) \
       {response_expand(&argc, &argv);}
#  endif
#endif

#ifdef WIN32 /* Windows NT */
#  define HAVE_SYS_UTIME_H
#  define NO_UTIME_H
#  define PATH_SEP2 '\\'
#  define PATH_SEP3 ':'
#  define MAX_PATH_LEN  260
#  define NO_CHOWN
#  define PROTO
#  define STDC_HEADERS
#  define SET_BINARY_MODE(fd) setmode(fd, O_BINARY)
#  include <io.h>
#  include <malloc.h>
#  ifdef NTFAT
#    define NO_MULTIPLE_DOTS
#    define MAX_EXT_CHARS 3
#    define Z_SUFFIX "z"
#    define casemap(c) tolow(c) /* Force file names to lower case */
#  endif
#  define OS_CODE  0x0b
#endif

#ifdef MSDOS
#  ifdef __TURBOC__
#    include <alloc.h>
#    define DYN_ALLOC
     /* Turbo C 2.0 does not accept static allocations of large arrays */
     void * fcalloc (unsigned items, unsigned size);
     void fcfree (void *ptr);
#  else /* MSC */
#    include <malloc.h>
#    define fcalloc(nitems,itemsize) halloc((long)(nitems),(itemsize))
#    define fcfree(ptr) hfree(ptr)
#  endif
#else
#  ifdef MAXSEG_64K
#    define fcalloc(items,size) calloc((items),(size))
#  else
#    define fcalloc(items,size) malloc((size_t)(items)*(size_t)(size))
#  endif
#  define fcfree(ptr) free(ptr)
#endif

#if defined(VAXC) || defined(VMS)
#  define PATH_SEP ']'
#  define PATH_SEP2 ':'
#  define SUFFIX_SEP ';'
#  define NO_MULTIPLE_DOTS
#  define Z_SUFFIX "-gz"
#  define RECORD_IO 1
#  define casemap(c) tolow(c)
#  define OS_CODE  0x02
#  define OPTIONS_VAR "GZIP_OPT"
#  define STDC_HEADERS
#  define NO_UTIME
#  define EXPAND(argc,argv) vms_expand_args(&argc,&argv);
#  include <file.h>
#  define unlink delete
#  ifdef VAXC
#    define NO_FCNTL_H
#    include <unixio.h>
#  endif
#endif

#ifdef AMIGA
#  define PATH_SEP2 ':'
#  define STDC_HEADERS
#  define OS_CODE  0x01
#  define ASMV
#  ifdef __GNUC__
#    define DIRENT
#    define HAVE_UNISTD_H
#  else /* SASC */
#    define NO_STDIN_FSTAT
#    define SYSDIR
#    define NO_SYMLINK
#    define NO_CHOWN
#    define NO_FCNTL_H
#    include <fcntl.h> /* for read() and write() */
#    define direct dirent
     extern void _expand_args(int *argc, char ***argv);
#    define EXPAND(argc,argv) _expand_args(&argc,&argv);
#    undef  O_BINARY /* disable useless --ascii option */
#  endif
#endif

#if defined(ATARI) || defined(atarist)
#  ifndef STDC_HEADERS
#    define STDC_HEADERS
#    define HAVE_UNISTD_H
#    define DIRENT
#  endif
#  define ASMV
#  define OS_CODE  0x05
#  ifdef TOSFS
#    define PATH_SEP2 '\\'
#    define PATH_SEP3 ':'
#    define MAX_PATH_LEN  128
#    define NO_MULTIPLE_DOTS
#    define MAX_EXT_CHARS 3
#    define Z_SUFFIX "z"
#    define NO_CHOWN
#    define casemap(c) tolow(c) /* Force file names to lower case */
#    define NO_SYMLINK
#  endif
#endif

#ifdef MACOS
#  define PATH_SEP ':'
#  define DYN_ALLOC
#  define PROTO
#  define NO_STDIN_FSTAT
#  define NO_CHOWN
#  define NO_UTIME
#  define chmod(file, mode) (0)
#  define OPEN(name, flags, mode) open(name, flags)
#  define OS_CODE  0x07
#  ifdef MPW
#    define isatty(fd) ((fd) <= 2)
#  endif
#endif

#ifdef __50SERIES /* Prime/PRIMOS */
#  define PATH_SEP '>'
#  define STDC_HEADERS
#  define NO_MEMORY_H
#  define NO_UTIME_H
#  define NO_UTIME
#  define NO_CHOWN 
#  define NO_STDIN_FSTAT 
#  define NO_SIZE_CHECK 
#  define NO_SYMLINK
#  define RECORD_IO  1
#  define casemap(c)  tolow(c) /* Force file names to lower case */
#  define put_char(c) put_byte((c) & 0x7F)
#  define get_char(c) ascii2pascii(get_byte())
#  define OS_CODE  0x0F    /* temporary, subject to change */
#  ifdef SIGTERM
#    undef SIGTERM         /* We don't want a signal handler for SIGTERM */
#  endif
#endif

#if defined(pyr) && !defined(NOMEMCPY) /* Pyramid */
#  define NOMEMCPY /* problem with overlapping copies */
#endif

#ifdef TOPS20
#  define OS_CODE  0x0a
#endif

#ifndef unix
#  define NO_ST_INO /* don't rely on inode numbers */
#endif


        /* Common defaults */

#ifndef OS_CODE
#  define OS_CODE  0x03  /* assume Unix */
#endif

#ifndef PATH_SEP
#  define PATH_SEP '/'
#endif

#ifndef casemap
#  define casemap(c) (c)
#endif

#ifndef OPTIONS_VAR
#  define OPTIONS_VAR "GZIP"
#endif

#ifndef Z_SUFFIX
#  define Z_SUFFIX ".gz"
#endif

#ifdef MAX_EXT_CHARS
#  define MAX_SUFFIX  MAX_EXT_CHARS
#else
#  define MAX_SUFFIX  30
#endif

#ifndef MAKE_LEGAL_NAME
#  ifdef NO_MULTIPLE_DOTS
#    define MAKE_LEGAL_NAME(name)   make_simple_name(name)
#  else
#    define MAKE_LEGAL_NAME(name)
#  endif
#endif

#ifndef MIN_PART
#  define MIN_PART 3
   /* keep at least MIN_PART chars between dots in a file name. */
#endif

#ifndef EXPAND
#  define EXPAND(argc,argv)
#endif

#ifndef RECORD_IO
#  define RECORD_IO 0
#endif

#ifndef SET_BINARY_MODE
#  define SET_BINARY_MODE(fd)
#endif

#ifndef OPEN
#  define OPEN(name, flags, mode) open(name, flags, mode)
#endif

#ifndef get_char
#  define get_char() get_byte()
#endif

#ifndef put_char
#  define put_char(c) put_byte(c)
#endif
/* bits.c -- output variable-length bit strings
 * Copyright (C) 1992-1993 Jean-loup Gailly
 * This is free software; you can redistribute it and/or modify it under the
 * terms of the GNU General Public License, see the file COPYING.
 */


/*
 *  PURPOSE
 *
 *      Output variable-length bit strings. Compression can be done
 *      to a file or to memory. (The latter is not supported in this version.)
 *
 *  DISCUSSION
 *
 *      The PKZIP "deflate" file format interprets compressed file data
 *      as a sequence of bits.  Multi-bit strings in the file may cross
 *      byte boundaries without restriction.
 *
 *      The first bit of each byte is the low-order bit.
 *
 *      The routines in this file allow a variable-length bit value to
 *      be output right-to-left (useful for literal values). For
 *      left-to-right output (useful for code strings from the tree routines),
 *      the bits must have been reversed first with bi_reverse().
 *
 *      For in-memory compression, the compressed bit stream goes directly
 *      into the requested output buffer. The input data is read in blocks
 *      by the mem_read() function. The buffer is limited to 64K on 16 bit
 *      machines.
 *
 *  INTERFACE
 *
 *      void bi_init (FILE *zipfile)
 *          Initialize the bit string routines.
 *
 *      void send_bits (int value, int length)
 *          Write out a bit string, taking the source bits right to
 *          left.
 *
 *      int bi_reverse (int value, int length)
 *          Reverse the bits of a bit string, taking the source bits left to
 *          right and emitting them right to left.
 *
 *      void bi_windup (void)
 *          Write out any remaining bits in an incomplete byte.
 *
 *      void copy_block(char *buf, unsigned len, int header)
 *          Copy a stored block to the zip file, storing first the length and
 *          its one's complement if requested.
 *
 */

#ifdef DEBUG
#  include <stdio.h>
#endif

#ifdef RCSID
static char rcsid[] = "$Id: gzip.c,v 1.3 1999/10/16 15:48:40 andersen Exp $";
#endif

/* ===========================================================================
 * Local data used by the "bit string" routines.
 */

local file_t zfile; /* output gzip file */

local unsigned short bi_buf;
/* Output buffer. bits are inserted starting at the bottom (least significant
 * bits).
 */

#define Buf_size (8 * 2*sizeof(char))
/* Number of bits used within bi_buf. (bi_buf might be implemented on
 * more than 16 bits on some systems.)
 */

local int bi_valid;
/* Number of valid bits in bi_buf.  All bits above the last valid bit
 * are always zero.
 */

int (*read_buf) OF((char *buf, unsigned size));
/* Current input function. Set to mem_read for in-memory compression */

#ifdef DEBUG
  ulg bits_sent;   /* bit length of the compressed data */
#endif

/* ===========================================================================
 * Initialize the bit string routines.
 */
void bi_init (zipfile)
    file_t zipfile; /* output zip file, NO_FILE for in-memory compression */
{
    zfile  = zipfile;
    bi_buf = 0;
    bi_valid = 0;
#ifdef DEBUG
    bits_sent = 0L;
#endif

    /* Set the defaults for file compression. They are set by memcompress
     * for in-memory compression.
     */
    if (zfile != NO_FILE) {
        read_buf  = file_read;
    }
}

/* ===========================================================================
 * Send a value on a given number of bits.
 * IN assertion: length <= 16 and value fits in length bits.
 */
void send_bits(value, length)
    int value;  /* value to send */
    int length; /* number of bits */
{
#ifdef DEBUG
    Tracev((stderr," l %2d v %4x ", length, value));
    Assert(length > 0 && length <= 15, "invalid length");
    bits_sent += (ulg)length;
#endif
    /* If not enough room in bi_buf, use (valid) bits from bi_buf and
     * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
     * unused bits in value.
     */
    if (bi_valid > (int)Buf_size - length) {
        bi_buf |= (value << bi_valid);
        put_short(bi_buf);
        bi_buf = (ush)value >> (Buf_size - bi_valid);
        bi_valid += length - Buf_size;
    } else {
        bi_buf |= value << bi_valid;
        bi_valid += length;
    }
}

/* ===========================================================================
 * Reverse the first len bits of a code, using straightforward code (a faster
 * method would use a table)
 * IN assertion: 1 <= len <= 15
 */
unsigned bi_reverse(code, len)
    unsigned code; /* the value to invert */
    int len;       /* its bit length */
{
    register unsigned res = 0;
    do {
        res |= code & 1;
        code >>= 1, res <<= 1;
    } while (--len > 0);
    return res >> 1;
}

/* ===========================================================================
 * Write out any remaining bits in an incomplete byte.
 */
void bi_windup()
{
    if (bi_valid > 8) {
        put_short(bi_buf);
    } else if (bi_valid > 0) {
        put_byte(bi_buf);
    }
    bi_buf = 0;
    bi_valid = 0;
#ifdef DEBUG
    bits_sent = (bits_sent+7) & ~7;
#endif
}

/* ===========================================================================
 * Copy a stored block to the zip file, storing first the length and its
 * one's complement if requested.
 */
void copy_block(buf, len, header)
    char     *buf;    /* the input data */
    unsigned len;     /* its length */
    int      header;  /* true if block header must be written */
{
    bi_windup();              /* align on byte boundary */

    if (header) {
        put_short((ush)len);   
        put_short((ush)~len);
#ifdef DEBUG
        bits_sent += 2*16;
#endif
    }
#ifdef DEBUG
    bits_sent += (ulg)len<<3;
#endif
    while (len--) {
#ifdef CRYPT
        int t;
        if (key) zencode(*buf, t);
#endif
        put_byte(*buf++);
    }
}
/* deflate.c -- compress data using the deflation algorithm
 * Copyright (C) 1992-1993 Jean-loup Gailly
 * This is free software; you can redistribute it and/or modify it under the
 * terms of the GNU General Public License, see the file COPYING.
 */

/*
 *  PURPOSE
 *
 *      Identify new text as repetitions of old text within a fixed-
 *      length sliding window trailing behind the new text.
 *
 *  DISCUSSION
 *
 *      The "deflation" process depends on being able to identify portions
 *      of the input text which are identical to earlier input (within a
 *      sliding window trailing behind the input currently being processed).
 *
 *      The most straightforward technique turns out to be the fastest for
 *      most input files: try all possible matches and select the longest.
 *      The key feature of this algorithm is that insertions into the string
 *      dictionary are very simple and thus fast, and deletions are avoided
 *      completely. Insertions are performed at each input character, whereas
 *      string matches are performed only when the previous match ends. So it
 *      is preferable to spend more time in matches to allow very fast string
 *      insertions and avoid deletions. The matching algorithm for small
 *      strings is inspired from that of Rabin & Karp. A brute force approach
 *      is used to find longer strings when a small match has been found.
 *      A similar algorithm is used in comic (by Jan-Mark Wams) and freeze
 *      (by Leonid Broukhis).
 *         A previous version of this file used a more sophisticated algorithm
 *      (by Fiala and Greene) which is guaranteed to run in linear amortized
 *      time, but has a larger average cost, uses more memory and is patented.
 *      However the F&G algorithm may be faster for some highly redundant
 *      files if the parameter max_chain_length (described below) is too large.
 *
 *  ACKNOWLEDGEMENTS
 *
 *      The idea of lazy evaluation of matches is due to Jan-Mark Wams, and
 *      I found it in 'freeze' written by Leonid Broukhis.
 *      Thanks to many info-zippers for bug reports and testing.
 *
 *  REFERENCES
 *
 *      APPNOTE.TXT documentation file in PKZIP 1.93a distribution.
 *
 *      A description of the Rabin and Karp algorithm is given in the book
 *         "Algorithms" by R. Sedgewick, Addison-Wesley, p252.
 *
 *      Fiala,E.R., and Greene,D.H.
 *         Data Compression with Finite Windows, Comm.ACM, 32,4 (1989) 490-595
 *
 *  INTERFACE
 *
 *      void lm_init (int pack_level, ush *flags)
 *          Initialize the "longest match" routines for a new file
 *
 *      ulg deflate (void)
 *          Processes a new input file and return its compressed length. Sets
 *          the compressed length, crc, deflate flags and internal file
 *          attributes.
 */

#include <stdio.h>

#ifdef RCSID
static char rcsid[] = "$Id: gzip.c,v 1.3 1999/10/16 15:48:40 andersen Exp $";
#endif

/* ===========================================================================
 * Configuration parameters
 */

/* Compile with MEDIUM_MEM to reduce the memory requirements or
 * with SMALL_MEM to use as little memory as possible. Use BIG_MEM if the
 * entire input file can be held in memory (not possible on 16 bit systems).
 * Warning: defining these symbols affects HASH_BITS (see below) and thus
 * affects the compression ratio. The compressed output
 * is still correct, and might even be smaller in some cases.
 */

#ifdef SMALL_MEM
#   define HASH_BITS  13  /* Number of bits used to hash strings */
#endif
#ifdef MEDIUM_MEM
#   define HASH_BITS  14
#endif
#ifndef HASH_BITS
#   define HASH_BITS  15
   /* For portability to 16 bit machines, do not use values above 15. */
#endif

/* To save space (see unlzw.c), we overlay prev+head with tab_prefix and
 * window with tab_suffix. Check that we can do this:
 */
#if (WSIZE<<1) > (1<<BITS)
   error: cannot overlay window with tab_suffix and prev with tab_prefix0
#endif
#if HASH_BITS > BITS-1
   error: cannot overlay head with tab_prefix1
#endif

#define HASH_SIZE (unsigned)(1<<HASH_BITS)
#define HASH_MASK (HASH_SIZE-1)
#define WMASK     (WSIZE-1)
/* HASH_SIZE and WSIZE must be powers of two */

#define NIL 0
/* Tail of hash chains */

#define FAST 4
#define SLOW 2
/* speed options for the general purpose bit flag */

#ifndef TOO_FAR
#  define TOO_FAR 4096
#endif
/* Matches of length 3 are discarded if their distance exceeds TOO_FAR */

/* ===========================================================================
 * Local data used by the "longest match" routines.
 */

typedef ush Pos;
typedef unsigned IPos;
/* A Pos is an index in the character window. We use short instead of int to
 * save space in the various tables. IPos is used only for parameter passing.
 */

/* DECLARE(uch, window, 2L*WSIZE); */
/* Sliding window. Input bytes are read into the second half of the window,
 * and move to the first half later to keep a dictionary of at least WSIZE
 * bytes. With this organization, matches are limited to a distance of
 * WSIZE-MAX_MATCH bytes, but this ensures that IO is always
 * performed with a length multiple of the block size. Also, it limits
 * the window size to 64K, which is quite useful on MSDOS.
 * To do: limit the window size to WSIZE+BSZ if SMALL_MEM (the code would
 * be less efficient).
 */

/* DECLARE(Pos, prev, WSIZE); */
/* Link to older string with same hash index. To limit the size of this
 * array to 64K, this link is maintained only for the last 32K strings.
 * An index in this array is thus a window index modulo 32K.
 */

/* DECLARE(Pos, head, 1<<HASH_BITS); */
/* Heads of the hash chains or NIL. */

ulg window_size = (ulg)2*WSIZE;
/* window size, 2*WSIZE except for MMAP or BIG_MEM, where it is the
 * input file length plus MIN_LOOKAHEAD.
 */

long block_start;
/* window position at the beginning of the current output block. Gets
 * negative when the window is moved backwards.
 */

local unsigned ins_h;  /* hash index of string to be inserted */

#define H_SHIFT  ((HASH_BITS+MIN_MATCH-1)/MIN_MATCH)
/* Number of bits by which ins_h and del_h must be shifted at each
 * input step. It must be such that after MIN_MATCH steps, the oldest
 * byte no longer takes part in the hash key, that is:
 *   H_SHIFT * MIN_MATCH >= HASH_BITS
 */

unsigned int near prev_length;
/* Length of the best match at previous step. Matches not greater than this
 * are discarded. This is used in the lazy match evaluation.
 */

      unsigned near strstart;      /* start of string to insert */
      unsigned near match_start;   /* start of matching string */
local int           eofile;        /* flag set at end of input file */
local unsigned      lookahead;     /* number of valid bytes ahead in window */

unsigned near max_chain_length;
/* To speed up deflation, hash chains are never searched beyond this length.
 * A higher limit improves compression ratio but degrades the speed.
 */

local unsigned int max_lazy_match;
/* Attempt to find a better match only when the current match is strictly
 * smaller than this value. This mechanism is used only for compression
 * levels >= 4.
 */
#define max_insert_length  max_lazy_match
/* Insert new strings in the hash table only if the match length
 * is not greater than this length. This saves time but degrades compression.
 * max_insert_length is used only for compression levels <= 3.
 */

unsigned near good_match;
/* Use a faster search when the previous match is longer than this */


/* Values for max_lazy_match, good_match and max_chain_length, depending on
 * the desired pack level (0..9). The values given below have been tuned to
 * exclude worst case performance for pathological files. Better values may be
 * found for specific files.
 */

typedef struct config {
   ush good_length; /* reduce lazy search above this match length */
   ush max_lazy;    /* do not perform lazy search above this match length */
   ush nice_length; /* quit search above this match length */
   ush max_chain;
} config;

#ifdef  FULL_SEARCH
# define nice_match MAX_MATCH
#else
  int near nice_match; /* Stop searching when current match exceeds this */
#endif

local config configuration_table = 
/* 9 */ {32, 258, 258, 4096}; /* maximum compression */

/* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different
 * meaning.
 */

#define EQUAL 0
/* result of memcmp for equal strings */

/* ===========================================================================
 *  Prototypes for local functions.
 */
local void fill_window   OF((void));

      int  longest_match OF((IPos cur_match));
#ifdef ASMV
      void match_init OF((void)); /* asm code initialization */
#endif

#ifdef DEBUG
local  void check_match OF((IPos start, IPos match, int length));
#endif

/* ===========================================================================
 * Update a hash value with the given input byte
 * IN  assertion: all calls to to UPDATE_HASH are made with consecutive
 *    input characters, so that a running hash key can be computed from the
 *    previous key instead of complete recalculation each time.
 */
#define UPDATE_HASH(h,c) (h = (((h)<<H_SHIFT) ^ (c)) & HASH_MASK)

/* ===========================================================================
 * Insert string s in the dictionary and set match_head to the previous head
 * of the hash chain (the most recent string with same hash key). Return
 * the previous length of the hash chain.
 * IN  assertion: all calls to to INSERT_STRING are made with consecutive
 *    input characters and the first MIN_MATCH bytes of s are valid
 *    (except for the last MIN_MATCH-1 bytes of the input file).
 */
#define INSERT_STRING(s, match_head) \
   (UPDATE_HASH(ins_h, window[(s) + MIN_MATCH-1]), \
    prev[(s) & WMASK] = match_head = head[ins_h], \
    head[ins_h] = (s))

/* ===========================================================================
 * Initialize the "longest match" routines for a new file
 */
void lm_init (flags)
    ush *flags;     /* general purpose bit flag */
{
    register unsigned j;

    /* Initialize the hash table. */
#if defined(MAXSEG_64K) && HASH_BITS == 15
    for (j = 0;  j < HASH_SIZE; j++) head[j] = NIL;
#else
    memzero((char*)head, HASH_SIZE*sizeof(*head));
#endif
    /* prev will be initialized on the fly */

    /* Set the default configuration parameters:
     */
    max_lazy_match   = configuration_table.max_lazy;
    good_match       = configuration_table.good_length;
#ifndef FULL_SEARCH
    nice_match       = configuration_table.nice_length;
#endif
    max_chain_length = configuration_table.max_chain;
    *flags |= SLOW;
    /* ??? reduce max_chain_length for binary files */

    strstart = 0;
    block_start = 0L;
#ifdef ASMV
    match_init(); /* initialize the asm code */
#endif

    lookahead = read_buf((char*)window,
                         sizeof(int) <= 2 ? (unsigned)WSIZE : 2*WSIZE);

    if (lookahead == 0 || lookahead == (unsigned)EOF) {
       eofile = 1, lookahead = 0;
       return;
    }
    eofile = 0;
    /* Make sure that we always have enough lookahead. This is important
     * if input comes from a device such as a tty.
     */
    while (lookahead < MIN_LOOKAHEAD && !eofile) fill_window();

    ins_h = 0;
    for (j=0; j<MIN_MATCH-1; j++) UPDATE_HASH(ins_h, window[j]);
    /* If lookahead < MIN_MATCH, ins_h is garbage, but this is
     * not important since only literal bytes will be emitted.
     */
}

/* ===========================================================================
 * Set match_start to the longest match starting at the given string and
 * return its length. Matches shorter or equal to prev_length are discarded,
 * in which case the result is equal to prev_length and match_start is
 * garbage.
 * IN assertions: cur_match is the head of the hash chain for the current
 *   string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
 */
#ifndef ASMV
/* For MSDOS, OS/2 and 386 Unix, an optimized version is in match.asm or
 * match.s. The code is functionally equivalent, so you can use the C version
 * if desired.
 */
int longest_match(cur_match)
    IPos cur_match;                             /* current match */
{
    unsigned chain_length = max_chain_length;   /* max hash chain length */
    register uch *scan = window + strstart;     /* current string */
    register uch *match;                        /* matched string */
    register int len;                           /* length of current match */
    int best_len = prev_length;                 /* best match length so far */
    IPos limit = strstart > (IPos)MAX_DIST ? strstart - (IPos)MAX_DIST : NIL;
    /* Stop when cur_match becomes <= limit. To simplify the code,
     * we prevent matches with the string of window index 0.
     */

/* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
 * It is easy to get rid of this optimization if necessary.
 */
#if HASH_BITS < 8 || MAX_MATCH != 258
   error: Code too clever
#endif

#ifdef UNALIGNED_OK
    /* Compare two bytes at a time. Note: this is not always beneficial.
     * Try with and without -DUNALIGNED_OK to check.
     */
    register uch *strend = window + strstart + MAX_MATCH - 1;
    register ush scan_start = *(ush*)scan;
    register ush scan_end   = *(ush*)(scan+best_len-1);
#else
    register uch *strend = window + strstart + MAX_MATCH;
    register uch scan_end1  = scan[best_len-1];
    register uch scan_end   = scan[best_len];
#endif

    /* Do not waste too much time if we already have a good match: */
    if (prev_length >= good_match) {
        chain_length >>= 2;
    }
    Assert(strstart <= window_size-MIN_LOOKAHEAD, "insufficient lookahead");

    do {
        Assert(cur_match < strstart, "no future");
        match = window + cur_match;

        /* Skip to next match if the match length cannot increase
         * or if the match length is less than 2:
         */
#if (defined(UNALIGNED_OK) && MAX_MATCH == 258)
        /* This code assumes sizeof(unsigned short) == 2. Do not use
         * UNALIGNED_OK if your compiler uses a different size.
         */
        if (*(ush*)(match+best_len-1) != scan_end ||
            *(ush*)match != scan_start) continue;

        /* It is not necessary to compare scan[2] and match[2] since they are
         * always equal when the other bytes match, given that the hash keys
         * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at
         * strstart+3, +5, ... up to strstart+257. We check for insufficient
         * lookahead only every 4th comparison; the 128th check will be made
         * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is
         * necessary to put more guard bytes at the end of the window, or
         * to check more often for insufficient lookahead.
         */
        scan++, match++;
        do {
        } while (*(ush*)(scan+=2) == *(ush*)(match+=2) &&
                 *(ush*)(scan+=2) == *(ush*)(match+=2) &&
                 *(ush*)(scan+=2) == *(ush*)(match+=2) &&
                 *(ush*)(scan+=2) == *(ush*)(match+=2) &&
                 scan < strend);
        /* The funny "do {}" generates better code on most compilers */

        /* Here, scan <= window+strstart+257 */
        Assert(scan <= window+(unsigned)(window_size-1), "wild scan");
        if (*scan == *match) scan++;

        len = (MAX_MATCH - 1) - (int)(strend-scan);
        scan = strend - (MAX_MATCH-1);

#else /* UNALIGNED_OK */

        if (match[best_len]   != scan_end  ||
            match[best_len-1] != scan_end1 ||
            *match            != *scan     ||
            *++match          != scan[1])      continue;

        /* The check at best_len-1 can be removed because it will be made
         * again later. (This heuristic is not always a win.)
         * It is not necessary to compare scan[2] and match[2] since they
         * are always equal when the other bytes match, given that
         * the hash keys are equal and that HASH_BITS >= 8.
         */
        scan += 2, match++;

        /* We check for insufficient lookahead only every 8th comparison;
         * the 256th check will be made at strstart+258.
         */
        do {
        } while (*++scan == *++match && *++scan == *++match &&
                 *++scan == *++match && *++scan == *++match &&
                 *++scan == *++match && *++scan == *++match &&
                 *++scan == *++match && *++scan == *++match &&
                 scan < strend);

        len = MAX_MATCH - (int)(strend - scan);
        scan = strend - MAX_MATCH;

#endif /* UNALIGNED_OK */

        if (len > best_len) {
            match_start = cur_match;
            best_len = len;
            if (len >= nice_match) break;
#ifdef UNALIGNED_OK
            scan_end = *(ush*)(scan+best_len-1);
#else
            scan_end1  = scan[best_len-1];
            scan_end   = scan[best_len];
#endif
        }
    } while ((cur_match = prev[cur_match & WMASK]) > limit
             && --chain_length != 0);

    return best_len;
}
#endif /* ASMV */

#ifdef DEBUG
/* ===========================================================================
 * Check that the match at match_start is indeed a match.
 */
local void check_match(start, match, length)
    IPos start, match;
    int length;
{
    /* check that the match is indeed a match */
    if (memcmp((char*)window + match,
                (char*)window + start, length) != EQUAL) {
        fprintf(stderr,
            " start %d, match %d, length %d\n",
            start, match, length);
        error("invalid match");
    }
    if (verbose > 1) {
        fprintf(stderr,"\\[%d,%d]", start-match, length);
        do { putc(window[start++], stderr); } while (--length != 0);
    }
}
#else
#  define check_match(start, match, length)
#endif

/* ===========================================================================
 * Fill the window when the lookahead becomes insufficient.
 * Updates strstart and lookahead, and sets eofile if end of input file.
 * IN assertion: lookahead < MIN_LOOKAHEAD && strstart + lookahead > 0
 * OUT assertions: at least one byte has been read, or eofile is set;
 *    file reads are performed for at least two bytes (required for the
 *    translate_eol option).
 */
local void fill_window()
{
    register unsigned n, m;
    unsigned more = (unsigned)(window_size - (ulg)lookahead - (ulg)strstart);
    /* Amount of free space at the end of the window. */

    /* If the window is almost full and there is insufficient lookahead,
     * move the upper half to the lower one to make room in the upper half.
     */
    if (more == (unsigned)EOF) {
        /* Very unlikely, but possible on 16 bit machine if strstart == 0
         * and lookahead == 1 (input done one byte at time)
         */
        more--;
    } else if (strstart >= WSIZE+MAX_DIST) {
        /* By the IN assertion, the window is not empty so we can't confuse
         * more == 0 with more == 64K on a 16 bit machine.
         */
        Assert(window_size == (ulg)2*WSIZE, "no sliding with BIG_MEM");

        memcpy((char*)window, (char*)window+WSIZE, (unsigned)WSIZE);
        match_start -= WSIZE;
        strstart    -= WSIZE; /* we now have strstart >= MAX_DIST: */

        block_start -= (long) WSIZE;

        for (n = 0; n < HASH_SIZE; n++) {
            m = head[n];
            head[n] = (Pos)(m >= WSIZE ? m-WSIZE : NIL);
        }
        for (n = 0; n < WSIZE; n++) {
            m = prev[n];
            prev[n] = (Pos)(m >= WSIZE ? m-WSIZE : NIL);
            /* If n is not on any hash chain, prev[n] is garbage but
             * its value will never be used.
             */
        }
        more += WSIZE;
    }
    /* At this point, more >= 2 */
    if (!eofile) {
        n = read_buf((char*)window+strstart+lookahead, more);
        if (n == 0 || n == (unsigned)EOF) {
            eofile = 1;
        } else {
            lookahead += n;
        }
    }
}

/* ===========================================================================
 * Flush the current block, with given end-of-file flag.
 * IN assertion: strstart is set to the end of the current match.
 */
#define FLUSH_BLOCK(eof) \
   flush_block(block_start >= 0L ? (char*)&window[(unsigned)block_start] : \
                (char*)NULL, (long)strstart - block_start, (eof))

/* ===========================================================================
 * Same as above, but achieves better compression. We use a lazy
 * evaluation for matches: a match is finally adopted only if there is
 * no better match at the next window position.
 */
ulg deflate()
{
    IPos hash_head;          /* head of hash chain */
    IPos prev_match;         /* previous match */
    int flush;               /* set if current block must be flushed */
    int match_available = 0; /* set if previous match exists */
    register unsigned match_length = MIN_MATCH-1; /* length of best match */
#ifdef DEBUG
    extern long isize;        /* byte length of input file, for debug only */
#endif

    /* Process the input block. */
    while (lookahead != 0) {
        /* Insert the string window[strstart .. strstart+2] in the
         * dictionary, and set hash_head to the head of the hash chain:
         */
        INSERT_STRING(strstart, hash_head);

        /* Find the longest match, discarding those <= prev_length.
         */
        prev_length = match_length, prev_match = match_start;
        match_length = MIN_MATCH-1;

        if (hash_head != NIL && prev_length < max_lazy_match &&
            strstart - hash_head <= MAX_DIST) {
            /* To simplify the code, we prevent matches with the string
             * of window index 0 (in particular we have to avoid a match
             * of the string with itself at the start of the input file).
             */
            match_length = longest_match (hash_head);
            /* longest_match() sets match_start */
            if (match_length > lookahead) match_length = lookahead;

            /* Ignore a length 3 match if it is too distant: */
            if (match_length == MIN_MATCH && strstart-match_start > TOO_FAR){
                /* If prev_match is also MIN_MATCH, match_start is garbage
                 * but we will ignore the current match anyway.
                 */
                match_length--;
            }
        }
        /* If there was a match at the previous step and the current
         * match is not better, output the previous match:
         */
        if (prev_length >= MIN_MATCH && match_length <= prev_length) {

            check_match(strstart-1, prev_match, prev_length);

            flush = ct_tally(strstart-1-prev_match, prev_length - MIN_MATCH);

            /* Insert in hash table all strings up to the end of the match.
             * strstart-1 and strstart are already inserted.
             */
            lookahead -= prev_length-1;
            prev_length -= 2;
            do {
                strstart++;
                INSERT_STRING(strstart, hash_head);
                /* strstart never exceeds WSIZE-MAX_MATCH, so there are
                 * always MIN_MATCH bytes ahead. If lookahead < MIN_MATCH
                 * these bytes are garbage, but it does not matter since the
                 * next lookahead bytes will always be emitted as literals.
                 */
            } while (--prev_length != 0);
            match_available = 0;
            match_length = MIN_MATCH-1;
            strstart++;
            if (flush) FLUSH_BLOCK(0), block_start = strstart;

        } else if (match_available) {
            /* If there was no match at the previous position, output a
             * single literal. If there was a match but the current match
             * is longer, truncate the previous match to a single literal.
             */
            Tracevv((stderr,"%c",window[strstart-1]));
            if (ct_tally (0, window[strstart-1])) {
                FLUSH_BLOCK(0), block_start = strstart;
            }
            strstart++;
            lookahead--;
        } else {
            /* There is no previous match to compare with, wait for
             * the next step to decide.
             */
            match_available = 1;
            strstart++;
            lookahead--;
        }
        Assert (strstart <= isize && lookahead <= isize, "a bit too far");

        /* Make sure that we always have enough lookahead, except
         * at the end of the input file. We need MAX_MATCH bytes
         * for the next match, plus MIN_MATCH bytes to insert the
         * string following the next match.
         */
        while (lookahead < MIN_LOOKAHEAD && !eofile) fill_window();
    }
    if (match_available) ct_tally (0, window[strstart-1]);

    return FLUSH_BLOCK(1); /* eof */
}
/* gzip (GNU zip) -- compress files with zip algorithm and 'compress' interface
 * Copyright (C) 1992-1993 Jean-loup Gailly
 * The unzip code was written and put in the public domain by Mark Adler.
 * Portions of the lzw code are derived from the public domain 'compress'
 * written by Spencer Thomas, Joe Orost, James Woods, Jim McKie, Steve Davies,
 * Ken Turkowski, Dave Mack and Peter Jannesen.
 *
 * See the license_msg below and the file COPYING for the software license.
 * See the file algorithm.doc for the compression algorithms and file formats.
 */

/* Compress files with zip algorithm and 'compress' interface.
 * See usage() and help() functions below for all options.
 * Outputs:
 *        file.gz:   compressed file with same mode, owner, and utimes
 *     or stdout with -c option or if stdin used as input.
 * If the output file name had to be truncated, the original name is kept
 * in the compressed file.
 * On MSDOS, file.tmp -> file.tmz. On VMS, file.tmp -> file.tmp-gz.
 *
 * Using gz on MSDOS would create too many file name conflicts. For
 * example, foo.txt -> foo.tgz (.tgz must be reserved as shorthand for
 * tar.gz). Similarly, foo.dir and foo.doc would both be mapped to foo.dgz.
 * I also considered 12345678.txt -> 12345txt.gz but this truncates the name
 * too heavily. There is no ideal solution given the MSDOS 8+3 limitation. 
 *
 * For the meaning of all compilation flags, see comments in Makefile.in.
 */

#ifdef RCSID
static char rcsid[] = "$Id: gzip.c,v 1.3 1999/10/16 15:48:40 andersen Exp $";
#endif

#include <ctype.h>
#include <sys/types.h>
#include <signal.h>
#include <sys/stat.h>
#include <errno.h>

                /* configuration */

#ifdef NO_TIME_H
#  include <sys/time.h>
#else
#  include <time.h>
#endif

#ifndef NO_FCNTL_H
#  include <fcntl.h>
#endif

#ifdef HAVE_UNISTD_H
#  include <unistd.h>
#endif

#if defined(STDC_HEADERS) || !defined(NO_STDLIB_H)
#  include <stdlib.h>
#else
   extern int errno;
#endif

#if defined(DIRENT)
#  include <dirent.h>
   typedef struct dirent dir_type;
#  define NLENGTH(dirent) ((int)strlen((dirent)->d_name))
#  define DIR_OPT "DIRENT"
#else
#  define NLENGTH(dirent) ((dirent)->d_namlen)
#  ifdef SYSDIR
#    include <sys/dir.h>
     typedef struct direct dir_type;
#    define DIR_OPT "SYSDIR"
#  else
#    ifdef SYSNDIR
#      include <sys/ndir.h>
       typedef struct direct dir_type;
#      define DIR_OPT "SYSNDIR"
#    else
#      ifdef NDIR
#        include <ndir.h>
         typedef struct direct dir_type;
#        define DIR_OPT "NDIR"
#      else
#        define NO_DIR
#        define DIR_OPT "NO_DIR"
#      endif
#    endif
#  endif
#endif

#ifndef NO_UTIME
#  ifndef NO_UTIME_H
#    include <utime.h>
#    define TIME_OPT "UTIME"
#  else
#    ifdef HAVE_SYS_UTIME_H
#      include <sys/utime.h>
#      define TIME_OPT "SYS_UTIME"
#    else
       struct utimbuf {
         time_t actime;
         time_t modtime;
       };
#      define TIME_OPT ""
#    endif
#  endif
#else
#  define TIME_OPT "NO_UTIME"
#endif

#if !defined(S_ISDIR) && defined(S_IFDIR)
#  define S_ISDIR(m) (((m) & S_IFMT) == S_IFDIR)
#endif
#if !defined(S_ISREG) && defined(S_IFREG)
#  define S_ISREG(m) (((m) & S_IFMT) == S_IFREG)
#endif

typedef RETSIGTYPE (*sig_type) OF((int));

#ifndef O_BINARY
#  define  O_BINARY  0  /* creation mode for open() */
#endif

#ifndef O_CREAT
   /* Pure BSD system? */
#  include <sys/file.h>
#  ifndef O_CREAT
#    define O_CREAT FCREAT
#  endif
#  ifndef O_EXCL
#    define O_EXCL FEXCL
#  endif
#endif

#ifndef S_IRUSR
#  define S_IRUSR 0400
#endif
#ifndef S_IWUSR
#  define S_IWUSR 0200
#endif
#define RW_USER (S_IRUSR | S_IWUSR)  /* creation mode for open() */

#ifndef MAX_PATH_LEN
#  define MAX_PATH_LEN   1024 /* max pathname length */
#endif

#ifndef SEEK_END
#  define SEEK_END 2
#endif

#ifdef NO_OFF_T
  typedef long off_t;
  off_t lseek OF((int fd, off_t offset, int whence));
#endif

/* Separator for file name parts (see shorten_name()) */
#ifdef NO_MULTIPLE_DOTS
#  define PART_SEP "-"
#else
#  define PART_SEP "."
#endif

                /* global buffers */

DECLARE(uch, inbuf,  INBUFSIZ +INBUF_EXTRA);
DECLARE(uch, outbuf, OUTBUFSIZ+OUTBUF_EXTRA);
DECLARE(ush, d_buf,  DIST_BUFSIZE);
DECLARE(uch, window, 2L*WSIZE);
#ifndef MAXSEG_64K
    DECLARE(ush, tab_prefix, 1L<<BITS);
#else
    DECLARE(ush, tab_prefix0, 1L<<(BITS-1));
    DECLARE(ush, tab_prefix1, 1L<<(BITS-1));
#endif

                /* local variables */

int ascii = 0;        /* convert end-of-lines to local OS conventions */
int to_stdout = 0;    /* output to stdout (-c) */
int decompress = 0;   /* decompress (-d) */
int no_name = -1;     /* don't save or restore the original file name */
int no_time = -1;     /* don't save or restore the original file time */
int foreground;       /* set if program run in foreground */
char *progname;       /* program name */
static int method = DEFLATED;/* compression method */
static int exit_code = OK;   /* program exit code */
int save_orig_name;   /* set if original name must be saved */
int last_member;      /* set for .zip and .Z files */
int part_nb;          /* number of parts in .gz file */
long time_stamp;      /* original time stamp (modification time) */
long ifile_size;      /* input file size, -1 for devices (debug only) */
char *env;            /* contents of GZIP env variable */
char **args = NULL;   /* argv pointer if GZIP env variable defined */
char z_suffix[MAX_SUFFIX+1]; /* default suffix (can be set with --suffix) */
int  z_len;           /* strlen(z_suffix) */

long bytes_in;             /* number of input bytes */
long bytes_out;            /* number of output bytes */
char ifname[MAX_PATH_LEN]; /* input file name */
char ofname[MAX_PATH_LEN]; /* output file name */
int  remove_ofname = 0;    /* remove output file on error */
struct stat istat;         /* status for input file */
int  ifd;                  /* input file descriptor */
int  ofd;                  /* output file descriptor */
unsigned insize;           /* valid bytes in inbuf */
unsigned inptr;            /* index of next byte to be processed in inbuf */
unsigned outcnt;           /* bytes in output buffer */

/* local functions */

local void treat_stdin  OF((void));
static int (*work) OF((int infile, int outfile)) = zip; /* function to call */

#define strequ(s1, s2) (strcmp((s1),(s2)) == 0)

/* ======================================================================== */
// int main (argc, argv)
//    int argc;
//    char **argv;
int gzip_main(int argc, char * * argv)
{
    foreground = signal(SIGINT, SIG_IGN) != SIG_IGN;
    if (foreground) {
        (void) signal (SIGINT, (sig_type)abort_gzip);
    }
#ifdef SIGTERM
    if (signal(SIGTERM, SIG_IGN) != SIG_IGN) {
        (void) signal(SIGTERM, (sig_type)abort_gzip);
    }
#endif
#ifdef SIGHUP
    if (signal(SIGHUP, SIG_IGN) != SIG_IGN) {
        (void) signal(SIGHUP,  (sig_type)abort_gzip);
    }
#endif

    strncpy(z_suffix, Z_SUFFIX, sizeof(z_suffix)-1);
    z_len = strlen(z_suffix);

    to_stdout = 1;

    /* Allocate all global buffers (for DYN_ALLOC option) */
    ALLOC(uch, inbuf,  INBUFSIZ +INBUF_EXTRA);
    ALLOC(uch, outbuf, OUTBUFSIZ+OUTBUF_EXTRA);
    ALLOC(ush, d_buf,  DIST_BUFSIZE);
    ALLOC(uch, window, 2L*WSIZE);
#ifndef MAXSEG_64K
    ALLOC(ush, tab_prefix, 1L<<BITS);
#else
    ALLOC(ush, tab_prefix0, 1L<<(BITS-1));
    ALLOC(ush, tab_prefix1, 1L<<(BITS-1));
#endif

    /* And get to work */
        treat_stdin();
    do_exit(exit_code);
    return exit_code; /* just to avoid lint warning */
}

/* ========================================================================
 * Compress or decompress stdin
 */
local void treat_stdin()
{
        SET_BINARY_MODE(fileno(stdout));
    strcpy(ifname, "stdin");
    strcpy(ofname, "stdout");

    /* Get the time stamp on the input file. */
    time_stamp = 0; /* time unknown by default */

    ifile_size = -1L; /* convention for unknown size */

    clear_bufs(); /* clear input and output buffers */
    to_stdout = 1;
    part_nb = 0;

    /* Actually do the compression/decompression. Loop over zipped members.
     */
        if ((*work)(fileno(stdin), fileno(stdout)) != OK) return;
}

/* ========================================================================
 * Free all dynamically allocated variables and exit with the given code.
 */
local void do_exit(int exitcode)
{
    static int in_exit = 0;

    if (in_exit) exit(exitcode);
    in_exit = 1;
    if (env != NULL)  free(env),  env  = NULL;
    if (args != NULL) free((char*)args), args = NULL;
    FREE(inbuf);
    FREE(outbuf);
    FREE(d_buf);
    FREE(window);
#ifndef MAXSEG_64K
    FREE(tab_prefix);
#else
    FREE(tab_prefix0);
    FREE(tab_prefix1);
#endif
    exit(exitcode);
}
/* trees.c -- output deflated data using Huffman coding
 * Copyright (C) 1992-1993 Jean-loup Gailly
 * This is free software; you can redistribute it and/or modify it under the
 * terms of the GNU General Public License, see the file COPYING.
 */

/*
 *  PURPOSE
 *
 *      Encode various sets of source values using variable-length
 *      binary code trees.
 *
 *  DISCUSSION
 *
 *      The PKZIP "deflation" process uses several Huffman trees. The more
 *      common source values are represented by shorter bit sequences.
 *
 *      Each code tree is stored in the ZIP file in a compressed form
 *      which is itself a Huffman encoding of the lengths of
 *      all the code strings (in ascending order by source values).
 *      The actual code strings are reconstructed from the lengths in
 *      the UNZIP process, as described in the "application note"
 *      (APPNOTE.TXT) distributed as part of PKWARE's PKZIP program.
 *
 *  REFERENCES
 *
 *      Lynch, Thomas J.
 *          Data Compression:  Techniques and Applications, pp. 53-55.
 *          Lifetime Learning Publications, 1985.  ISBN 0-534-03418-7.
 *
 *      Storer, James A.
 *          Data Compression:  Methods and Theory, pp. 49-50.
 *          Computer Science Press, 1988.  ISBN 0-7167-8156-5.
 *
 *      Sedgewick, R.
 *          Algorithms, p290.
 *          Addison-Wesley, 1983. ISBN 0-201-06672-6.
 *
 *  INTERFACE
 *
 *      void ct_init (ush *attr, int *methodp)
 *          Allocate the match buffer, initialize the various tables and save
 *          the location of the internal file attribute (ascii/binary) and
 *          method (DEFLATE/STORE)
 *
 *      void ct_tally (int dist, int lc);
 *          Save the match info and tally the frequency counts.
 *
 *      long flush_block (char *buf, ulg stored_len, int eof)
 *          Determine the best encoding for the current block: dynamic trees,
 *          static trees or store, and output the encoded block to the zip
 *          file. Returns the total compressed length for the file so far.
 *
 */

#include <ctype.h>

#ifdef RCSID
static char rcsid[] = "$Id: gzip.c,v 1.3 1999/10/16 15:48:40 andersen Exp $";
#endif

/* ===========================================================================
 * Constants
 */

#define MAX_BITS 15
/* All codes must not exceed MAX_BITS bits */

#define MAX_BL_BITS 7
/* Bit length codes must not exceed MAX_BL_BITS bits */

#define LENGTH_CODES 29
/* number of length codes, not counting the special END_BLOCK code */

#define LITERALS  256
/* number of literal bytes 0..255 */

#define END_BLOCK 256
/* end of block literal code */

#define L_CODES (LITERALS+1+LENGTH_CODES)
/* number of Literal or Length codes, including the END_BLOCK code */

#define D_CODES   30
/* number of distance codes */

#define BL_CODES  19
/* number of codes used to transfer the bit lengths */


local int near extra_lbits[LENGTH_CODES] /* extra bits for each length code */
   = {0,0,0,0,0,0,0,0,1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4,5,5,5,5,0};

local int near extra_dbits[D_CODES] /* extra bits for each distance code */
   = {0,0,0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,13,13};

local int near extra_blbits[BL_CODES]/* extra bits for each bit length code */
   = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7};

#define STORED_BLOCK 0
#define STATIC_TREES 1
#define DYN_TREES    2
/* The three kinds of block type */

#ifndef LIT_BUFSIZE
#  ifdef SMALL_MEM
#    define LIT_BUFSIZE  0x2000
#  else
#  ifdef MEDIUM_MEM
#    define LIT_BUFSIZE  0x4000
#  else
#    define LIT_BUFSIZE  0x8000
#  endif
#  endif
#endif
#ifndef DIST_BUFSIZE
#  define DIST_BUFSIZE  LIT_BUFSIZE
#endif
/* Sizes of match buffers for literals/lengths and distances.  There are
 * 4 reasons for limiting LIT_BUFSIZE to 64K:
 *   - frequencies can be kept in 16 bit counters
 *   - if compression is not successful for the first block, all input data is
 *     still in the window so we can still emit a stored block even when input
 *     comes from standard input.  (This can also be done for all blocks if
 *     LIT_BUFSIZE is not greater than 32K.)
 *   - if compression is not successful for a file smaller than 64K, we can
 *     even emit a stored file instead of a stored block (saving 5 bytes).
 *   - creating new Huffman trees less frequently may not provide fast
 *     adaptation to changes in the input data statistics. (Take for
 *     example a binary file with poorly compressible code followed by
 *     a highly compressible string table.) Smaller buffer sizes give
 *     fast adaptation but have of course the overhead of transmitting trees
 *     more frequently.
 *   - I can't count above 4
 * The current code is general and allows DIST_BUFSIZE < LIT_BUFSIZE (to save
 * memory at the expense of compression). Some optimizations would be possible
 * if we rely on DIST_BUFSIZE == LIT_BUFSIZE.
 */
#if LIT_BUFSIZE > INBUFSIZ
    error cannot overlay l_buf and inbuf
#endif

#define REP_3_6      16
/* repeat previous bit length 3-6 times (2 bits of repeat count) */

#define REPZ_3_10    17
/* repeat a zero length 3-10 times  (3 bits of repeat count) */

#define REPZ_11_138  18
/* repeat a zero length 11-138 times  (7 bits of repeat count) */

/* ===========================================================================
 * Local data
 */

/* Data structure describing a single value and its code string. */
typedef struct ct_data {
    union {
        ush  freq;       /* frequency count */
        ush  code;       /* bit string */
    } fc;
    union {
        ush  dad;        /* father node in Huffman tree */
        ush  len;        /* length of bit string */
    } dl;
} ct_data;

#define Freq fc.freq
#define Code fc.code
#define Dad  dl.dad
#define Len  dl.len

#define HEAP_SIZE (2*L_CODES+1)
/* maximum heap size */

local ct_data near dyn_ltree[HEAP_SIZE];   /* literal and length tree */
local ct_data near dyn_dtree[2*D_CODES+1]; /* distance tree */

local ct_data near static_ltree[L_CODES+2];
/* The static literal tree. Since the bit lengths are imposed, there is no
 * need for the L_CODES extra codes used during heap construction. However
 * The codes 286 and 287 are needed to build a canonical tree (see ct_init
 * below).
 */

local ct_data near static_dtree[D_CODES];
/* The static distance tree. (Actually a trivial tree since all codes use
 * 5 bits.)
 */

local ct_data near bl_tree[2*BL_CODES+1];
/* Huffman tree for the bit lengths */

typedef struct tree_desc {
    ct_data near *dyn_tree;      /* the dynamic tree */
    ct_data near *static_tree;   /* corresponding static tree or NULL */
    int     near *extra_bits;    /* extra bits for each code or NULL */
    int     extra_base;          /* base index for extra_bits */
    int     elems;               /* max number of elements in the tree */
    int     max_length;          /* max bit length for the codes */
    int     max_code;            /* largest code with non zero frequency */
} tree_desc;

local tree_desc near l_desc =
{dyn_ltree, static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS, 0};

local tree_desc near d_desc =
{dyn_dtree, static_dtree, extra_dbits, 0,          D_CODES, MAX_BITS, 0};

local tree_desc near bl_desc =
{bl_tree, (ct_data near *)0, extra_blbits, 0,      BL_CODES, MAX_BL_BITS, 0};


local ush near bl_count[MAX_BITS+1];
/* number of codes at each bit length for an optimal tree */

local uch near bl_order[BL_CODES]
   = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15};
/* The lengths of the bit length codes are sent in order of decreasing
 * probability, to avoid transmitting the lengths for unused bit length codes.
 */

local int near heap[2*L_CODES+1]; /* heap used to build the Huffman trees */
local int heap_len;               /* number of elements in the heap */
local int heap_max;               /* element of largest frequency */
/* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used.
 * The same heap array is used to build all trees.
 */

local uch near depth[2*L_CODES+1];
/* Depth of each subtree used as tie breaker for trees of equal frequency */

local uch length_code[MAX_MATCH-MIN_MATCH+1];
/* length code for each normalized match length (0 == MIN_MATCH) */

local uch dist_code[512];
/* distance codes. The first 256 values correspond to the distances
 * 3 .. 258, the last 256 values correspond to the top 8 bits of
 * the 15 bit distances.
 */

local int near base_length[LENGTH_CODES];
/* First normalized length for each code (0 = MIN_MATCH) */

local int near base_dist[D_CODES];
/* First normalized distance for each code (0 = distance of 1) */

#define l_buf inbuf
/* DECLARE(uch, l_buf, LIT_BUFSIZE);  buffer for literals or lengths */

/* DECLARE(ush, d_buf, DIST_BUFSIZE); buffer for distances */

local uch near flag_buf[(LIT_BUFSIZE/8)];
/* flag_buf is a bit array distinguishing literals from lengths in
 * l_buf, thus indicating the presence or absence of a distance.
 */

local unsigned last_lit;    /* running index in l_buf */
local unsigned last_dist;   /* running index in d_buf */
local unsigned last_flags;  /* running index in flag_buf */
local uch flags;            /* current flags not yet saved in flag_buf */
local uch flag_bit;         /* current bit used in flags */
/* bits are filled in flags starting at bit 0 (least significant).
 * Note: these flags are overkill in the current code since we don't
 * take advantage of DIST_BUFSIZE == LIT_BUFSIZE.
 */

local ulg opt_len;        /* bit length of current block with optimal trees */
local ulg static_len;     /* bit length of current block with static trees */

local ulg compressed_len; /* total bit length of compressed file */

local ulg input_len;      /* total byte length of input file */
/* input_len is for debugging only since we can get it by other means. */

ush *file_type;        /* pointer to UNKNOWN, BINARY or ASCII */
int *file_method;      /* pointer to DEFLATE or STORE */

#ifdef DEBUG
extern ulg bits_sent;  /* bit length of the compressed data */
extern long isize;     /* byte length of input file */
#endif

extern long block_start;       /* window offset of current block */
extern unsigned near strstart; /* window offset of current string */

/* ===========================================================================
 * Local (static) routines in this file.
 */

local void init_block     OF((void));
local void pqdownheap     OF((ct_data near *tree, int k));
local void gen_bitlen     OF((tree_desc near *desc));
local void gen_codes      OF((ct_data near *tree, int max_code));
local void build_tree     OF((tree_desc near *desc));
local void scan_tree      OF((ct_data near *tree, int max_code));
local void send_tree      OF((ct_data near *tree, int max_code));
local int  build_bl_tree  OF((void));
local void send_all_trees OF((int lcodes, int dcodes, int blcodes));
local void compress_block OF((ct_data near *ltree, ct_data near *dtree));
local void set_file_type  OF((void));


#ifndef DEBUG
#  define send_code(c, tree) send_bits(tree[c].Code, tree[c].Len)
   /* Send a code of the given tree. c and tree must not have side effects */

#else /* DEBUG */
#  define send_code(c, tree) \
     { if (verbose>1) fprintf(stderr,"\ncd %3d ",(c)); \
       send_bits(tree[c].Code, tree[c].Len); }
#endif

#define d_code(dist) \
   ((dist) < 256 ? dist_code[dist] : dist_code[256+((dist)>>7)])
/* Mapping from a distance to a distance code. dist is the distance - 1 and
 * must not have side effects. dist_code[256] and dist_code[257] are never
 * used.
 */

#define MAX(a,b) (a >= b ? a : b)
/* the arguments must not have side effects */

/* ===========================================================================
 * Allocate the match buffer, initialize the various tables and save the
 * location of the internal file attribute (ascii/binary) and method
 * (DEFLATE/STORE).
 */
void ct_init(attr, methodp)
    ush  *attr;   /* pointer to internal file attribute */
    int  *methodp; /* pointer to compression method */
{
    int n;        /* iterates over tree elements */
    int bits;     /* bit counter */
    int length;   /* length value */
    int code;     /* code value */
    int dist;     /* distance index */

    file_type = attr;
    file_method = methodp;
    compressed_len = input_len = 0L;
        
    if (static_dtree[0].Len != 0) return; /* ct_init already called */

    /* Initialize the mapping length (0..255) -> length code (0..28) */
    length = 0;
    for (code = 0; code < LENGTH_CODES-1; code++) {
        base_length[code] = length;
        for (n = 0; n < (1<<extra_lbits[code]); n++) {
            length_code[length++] = (uch)code;
        }
    }
    Assert (length == 256, "ct_init: length != 256");
    /* Note that the length 255 (match length 258) can be represented
     * in two different ways: code 284 + 5 bits or code 285, so we
     * overwrite length_code[255] to use the best encoding:
     */
    length_code[length-1] = (uch)code;

    /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
    dist = 0;
    for (code = 0 ; code < 16; code++) {
        base_dist[code] = dist;
        for (n = 0; n < (1<<extra_dbits[code]); n++) {
            dist_code[dist++] = (uch)code;
        }
    }
    Assert (dist == 256, "ct_init: dist != 256");
    dist >>= 7; /* from now on, all distances are divided by 128 */
    for ( ; code < D_CODES; code++) {
        base_dist[code] = dist << 7;
        for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) {
            dist_code[256 + dist++] = (uch)code;
        }
    }
    Assert (dist == 256, "ct_init: 256+dist != 512");

    /* Construct the codes of the static literal tree */
    for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;
    n = 0;
    while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++;
    while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++;
    while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++;
    while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++;
    /* Codes 286 and 287 do not exist, but we must include them in the
     * tree construction to get a canonical Huffman tree (longest code
     * all ones)
     */
    gen_codes((ct_data near *)static_ltree, L_CODES+1);

    /* The static distance tree is trivial: */
    for (n = 0; n < D_CODES; n++) {
        static_dtree[n].Len = 5;
        static_dtree[n].Code = bi_reverse(n, 5);
    }

    /* Initialize the first block of the first file: */
    init_block();
}

/* ===========================================================================
 * Initialize a new block.
 */
local void init_block()
{
    int n; /* iterates over tree elements */

    /* Initialize the trees. */
    for (n = 0; n < L_CODES;  n++) dyn_ltree[n].Freq = 0;
    for (n = 0; n < D_CODES;  n++) dyn_dtree[n].Freq = 0;
    for (n = 0; n < BL_CODES; n++) bl_tree[n].Freq = 0;

    dyn_ltree[END_BLOCK].Freq = 1;
    opt_len = static_len = 0L;
    last_lit = last_dist = last_flags = 0;
    flags = 0; flag_bit = 1;
}

#define SMALLEST 1
/* Index within the heap array of least frequent node in the Huffman tree */


/* ===========================================================================
 * Remove the smallest element from the heap and recreate the heap with
 * one less element. Updates heap and heap_len.
 */
#define pqremove(tree, top) \
{\
    top = heap[SMALLEST]; \
    heap[SMALLEST] = heap[heap_len--]; \
    pqdownheap(tree, SMALLEST); \
}

/* ===========================================================================
 * Compares to subtrees, using the tree depth as tie breaker when
 * the subtrees have equal frequency. This minimizes the worst case length.
 */
#define smaller(tree, n, m) \
   (tree[n].Freq < tree[m].Freq || \
   (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))

/* ===========================================================================
 * Restore the heap property by moving down the tree starting at node k,
 * exchanging a node with the smallest of its two sons if necessary, stopping
 * when the heap property is re-established (each father smaller than its
 * two sons).
 */
local void pqdownheap(tree, k)
    ct_data near *tree;  /* the tree to restore */
    int k;               /* node to move down */
{
    int v = heap[k];
    int j = k << 1;  /* left son of k */
    while (j <= heap_len) {
        /* Set j to the smallest of the two sons: */
        if (j < heap_len && smaller(tree, heap[j+1], heap[j])) j++;

        /* Exit if v is smaller than both sons */
        if (smaller(tree, v, heap[j])) break;

        /* Exchange v with the smallest son */
        heap[k] = heap[j];  k = j;

        /* And continue down the tree, setting j to the left son of k */
        j <<= 1;
    }
    heap[k] = v;
}

/* ===========================================================================
 * Compute the optimal bit lengths for a tree and update the total bit length
 * for the current block.
 * IN assertion: the fields freq and dad are set, heap[heap_max] and
 *    above are the tree nodes sorted by increasing frequency.
 * OUT assertions: the field len is set to the optimal bit length, the
 *     array bl_count contains the frequencies for each bit length.
 *     The length opt_len is updated; static_len is also updated if stree is
 *     not null.
 */
local void gen_bitlen(desc)
    tree_desc near *desc; /* the tree descriptor */
{
    ct_data near *tree  = desc->dyn_tree;
    int near *extra     = desc->extra_bits;
    int base            = desc->extra_base;
    int max_code        = desc->max_code;
    int max_length      = desc->max_length;
    ct_data near *stree = desc->static_tree;
    int h;              /* heap index */
    int n, m;           /* iterate over the tree elements */
    int bits;           /* bit length */
    int xbits;          /* extra bits */
    ush f;              /* frequency */
    int overflow = 0;   /* number of elements with bit length too large */

    for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;

    /* In a first pass, compute the optimal bit lengths (which may
     * overflow in the case of the bit length tree).
     */
    tree[heap[heap_max]].Len = 0; /* root of the heap */

    for (h = heap_max+1; h < HEAP_SIZE; h++) {
        n = heap[h];
        bits = tree[tree[n].Dad].Len + 1;
        if (bits > max_length) bits = max_length, overflow++;
        tree[n].Len = (ush)bits;
        /* We overwrite tree[n].Dad which is no longer needed */

        if (n > max_code) continue; /* not a leaf node */

        bl_count[bits]++;
        xbits = 0;
        if (n >= base) xbits = extra[n-base];
        f = tree[n].Freq;
        opt_len += (ulg)f * (bits + xbits);
        if (stree) static_len += (ulg)f * (stree[n].Len + xbits);
    }
    if (overflow == 0) return;

    Trace((stderr,"\nbit length overflow\n"));
    /* This happens for example on obj2 and pic of the Calgary corpus */

    /* Find the first bit length which could increase: */
    do {
        bits = max_length-1;
        while (bl_count[bits] == 0) bits--;
        bl_count[bits]--;      /* move one leaf down the tree */
        bl_count[bits+1] += 2; /* move one overflow item as its brother */
        bl_count[max_length]--;
        /* The brother of the overflow item also moves one step up,
         * but this does not affect bl_count[max_length]
         */
        overflow -= 2;
    } while (overflow > 0);

    /* Now recompute all bit lengths, scanning in increasing frequency.
     * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
     * lengths instead of fixing only the wrong ones. This idea is taken
     * from 'ar' written by Haruhiko Okumura.)
     */
    for (bits = max_length; bits != 0; bits--) {
        n = bl_count[bits];
        while (n != 0) {
            m = heap[--h];
            if (m > max_code) continue;
            if (tree[m].Len != (unsigned) bits) {
                Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));
                opt_len += ((long)bits-(long)tree[m].Len)*(long)tree[m].Freq;
                tree[m].Len = (ush)bits;
            }
            n--;
        }
    }
}

/* ===========================================================================
 * Generate the codes for a given tree and bit counts (which need not be
 * optimal).
 * IN assertion: the array bl_count contains the bit length statistics for
 * the given tree and the field len is set for all tree elements.
 * OUT assertion: the field code is set for all tree elements of non
 *     zero code length.
 */
local void gen_codes (tree, max_code)
    ct_data near *tree;        /* the tree to decorate */
    int max_code;              /* largest code with non zero frequency */
{
    ush next_code[MAX_BITS+1]; /* next code value for each bit length */
    ush code = 0;              /* running code value */
    int bits;                  /* bit index */
    int n;                     /* code index */

    /* The distribution counts are first used to generate the code values
     * without bit reversal.
     */
    for (bits = 1; bits <= MAX_BITS; bits++) {
        next_code[bits] = code = (code + bl_count[bits-1]) << 1;
    }
    /* Check that the bit counts in bl_count are consistent. The last code
     * must be all ones.
     */
    Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
            "inconsistent bit counts");
    Tracev((stderr,"\ngen_codes: max_code %d ", max_code));

    for (n = 0;  n <= max_code; n++) {
        int len = tree[n].Len;
        if (len == 0) continue;
        /* Now reverse the bits */
        tree[n].Code = bi_reverse(next_code[len]++, len);

        Tracec(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
             n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));
    }
}

/* ===========================================================================
 * Construct one Huffman tree and assigns the code bit strings and lengths.
 * Update the total bit length for the current block.
 * IN assertion: the field freq is set for all tree elements.
 * OUT assertions: the fields len and code are set to the optimal bit length
 *     and corresponding code. The length opt_len is updated; static_len is
 *     also updated if stree is not null. The field max_code is set.
 */
local void build_tree(desc)
    tree_desc near *desc; /* the tree descriptor */
{
    ct_data near *tree   = desc->dyn_tree;
    ct_data near *stree  = desc->static_tree;
    int elems            = desc->elems;
    int n, m;          /* iterate over heap elements */
    int max_code = -1; /* largest code with non zero frequency */
    int node = elems;  /* next internal node of the tree */

    /* Construct the initial heap, with least frequent element in
     * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
     * heap[0] is not used.
     */
    heap_len = 0, heap_max = HEAP_SIZE;

    for (n = 0; n < elems; n++) {
        if (tree[n].Freq != 0) {
            heap[++heap_len] = max_code = n;
            depth[n] = 0;
        } else {
            tree[n].Len = 0;
        }
    }

    /* The pkzip format requires that at least one distance code exists,
     * and that at least one bit should be sent even if there is only one
     * possible code. So to avoid special checks later on we force at least
     * two codes of non zero frequency.
     */
    while (heap_len < 2) {
        int new = heap[++heap_len] = (max_code < 2 ? ++max_code : 0);
        tree[new].Freq = 1;
        depth[new] = 0;
        opt_len--; if (stree) static_len -= stree[new].Len;
        /* new is 0 or 1 so it does not have extra bits */
    }
    desc->max_code = max_code;

    /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
     * establish sub-heaps of increasing lengths:
     */
    for (n = heap_len/2; n >= 1; n--) pqdownheap(tree, n);

    /* Construct the Huffman tree by repeatedly combining the least two
     * frequent nodes.
     */
    do {
        pqremove(tree, n);   /* n = node of least frequency */
        m = heap[SMALLEST];  /* m = node of next least frequency */

        heap[--heap_max] = n; /* keep the nodes sorted by frequency */
        heap[--heap_max] = m;

        /* Create a new node father of n and m */
        tree[node].Freq = tree[n].Freq + tree[m].Freq;
        depth[node] = (uch) (MAX(depth[n], depth[m]) + 1);
        tree[n].Dad = tree[m].Dad = (ush)node;
#ifdef DUMP_BL_TREE
        if (tree == bl_tree) {
            fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)",
                    node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
        }
#endif
        /* and insert the new node in the heap */
        heap[SMALLEST] = node++;
        pqdownheap(tree, SMALLEST);

    } while (heap_len >= 2);

    heap[--heap_max] = heap[SMALLEST];

    /* At this point, the fields freq and dad are set. We can now
     * generate the bit lengths.
     */
    gen_bitlen((tree_desc near *)desc);

    /* The field len is now set, we can generate the bit codes */
    gen_codes ((ct_data near *)tree, max_code);
}

/* ===========================================================================
 * Scan a literal or distance tree to determine the frequencies of the codes
 * in the bit length tree. Updates opt_len to take into account the repeat
 * counts. (The contribution of the bit length codes will be added later
 * during the construction of bl_tree.)
 */
local void scan_tree (tree, max_code)
    ct_data near *tree; /* the tree to be scanned */
    int max_code;       /* and its largest code of non zero frequency */
{
    int n;                     /* iterates over all tree elements */
    int prevlen = -1;          /* last emitted length */
    int curlen;                /* length of current code */
    int nextlen = tree[0].Len; /* length of next code */
    int count = 0;             /* repeat count of the current code */
    int max_count = 7;         /* max repeat count */
    int min_count = 4;         /* min repeat count */

    if (nextlen == 0) max_count = 138, min_count = 3;
    tree[max_code+1].Len = (ush)0xffff; /* guard */

    for (n = 0; n <= max_code; n++) {
        curlen = nextlen; nextlen = tree[n+1].Len;
        if (++count < max_count && curlen == nextlen) {
            continue;
        } else if (count < min_count) {
            bl_tree[curlen].Freq += count;
        } else if (curlen != 0) {
            if (curlen != prevlen) bl_tree[curlen].Freq++;
            bl_tree[REP_3_6].Freq++;
        } else if (count <= 10) {
            bl_tree[REPZ_3_10].Freq++;
        } else {
            bl_tree[REPZ_11_138].Freq++;
        }
        count = 0; prevlen = curlen;
        if (nextlen == 0) {
            max_count = 138, min_count = 3;
        } else if (curlen == nextlen) {
            max_count = 6, min_count = 3;
        } else {
            max_count = 7, min_count = 4;
        }
    }
}

/* ===========================================================================
 * Send a literal or distance tree in compressed form, using the codes in
 * bl_tree.
 */
local void send_tree (tree, max_code)
    ct_data near *tree; /* the tree to be scanned */
    int max_code;       /* and its largest code of non zero frequency */
{
    int n;                     /* iterates over all tree elements */
    int prevlen = -1;          /* last emitted length */
    int curlen;                /* length of current code */
    int nextlen = tree[0].Len; /* length of next code */
    int count = 0;             /* repeat count of the current code */
    int max_count = 7;         /* max repeat count */
    int min_count = 4;         /* min repeat count */

    /* tree[max_code+1].Len = -1; */  /* guard already set */
    if (nextlen == 0) max_count = 138, min_count = 3;

    for (n = 0; n <= max_code; n++) {
        curlen = nextlen; nextlen = tree[n+1].Len;
        if (++count < max_count && curlen == nextlen) {
            continue;
        } else if (count < min_count) {
            do { send_code(curlen, bl_tree); } while (--count != 0);

        } else if (curlen != 0) {
            if (curlen != prevlen) {
                send_code(curlen, bl_tree); count--;
            }
            Assert(count >= 3 && count <= 6, " 3_6?");
            send_code(REP_3_6, bl_tree); send_bits(count-3, 2);

        } else if (count <= 10) {
            send_code(REPZ_3_10, bl_tree); send_bits(count-3, 3);

        } else {
            send_code(REPZ_11_138, bl_tree); send_bits(count-11, 7);
        }
        count = 0; prevlen = curlen;
        if (nextlen == 0) {
            max_count = 138, min_count = 3;
        } else if (curlen == nextlen) {
            max_count = 6, min_count = 3;
        } else {
            max_count = 7, min_count = 4;
        }
    }
}

/* ===========================================================================
 * Construct the Huffman tree for the bit lengths and return the index in
 * bl_order of the last bit length code to send.
 */
local int build_bl_tree()
{
    int max_blindex;  /* index of last bit length code of non zero freq */

    /* Determine the bit length frequencies for literal and distance trees */
    scan_tree((ct_data near *)dyn_ltree, l_desc.max_code);
    scan_tree((ct_data near *)dyn_dtree, d_desc.max_code);

    /* Build the bit length tree: */
    build_tree((tree_desc near *)(&bl_desc));
    /* opt_len now includes the length of the tree representations, except
     * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
     */

    /* Determine the number of bit length codes to send. The pkzip format
     * requires that at least 4 bit length codes be sent. (appnote.txt says
     * 3 but the actual value used is 4.)
     */
    for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) {
        if (bl_tree[bl_order[max_blindex]].Len != 0) break;
    }
    /* Update opt_len to include the bit length tree and counts */
    opt_len += 3*(max_blindex+1) + 5+5+4;
    Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld", opt_len, static_len));

    return max_blindex;
}

/* ===========================================================================
 * Send the header for a block using dynamic Huffman trees: the counts, the
 * lengths of the bit length codes, the literal tree and the distance tree.
 * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
 */
local void send_all_trees(lcodes, dcodes, blcodes)
    int lcodes, dcodes, blcodes; /* number of codes for each tree */
{
    int rank;                    /* index in bl_order */

    Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
    Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,
            "too many codes");
    Tracev((stderr, "\nbl counts: "));
    send_bits(lcodes-257, 5); /* not +255 as stated in appnote.txt */
    send_bits(dcodes-1,   5);
    send_bits(blcodes-4,  4); /* not -3 as stated in appnote.txt */
    for (rank = 0; rank < blcodes; rank++) {
        Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
        send_bits(bl_tree[bl_order[rank]].Len, 3);
    }
    Tracev((stderr, "\nbl tree: sent %ld", bits_sent));

    send_tree((ct_data near *)dyn_ltree, lcodes-1); /* send the literal tree */
    Tracev((stderr, "\nlit tree: sent %ld", bits_sent));

    send_tree((ct_data near *)dyn_dtree, dcodes-1); /* send the distance tree */
    Tracev((stderr, "\ndist tree: sent %ld", bits_sent));
}

/* ===========================================================================
 * Determine the best encoding for the current block: dynamic trees, static
 * trees or store, and output the encoded block to the zip file. This function
 * returns the total compressed length for the file so far.
 */
ulg flush_block(buf, stored_len, eof)
    char *buf;        /* input block, or NULL if too old */
    ulg stored_len;   /* length of input block */
    int eof;          /* true if this is the last block for a file */
{
    ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
    int max_blindex;  /* index of last bit length code of non zero freq */

    flag_buf[last_flags] = flags; /* Save the flags for the last 8 items */

     /* Check if the file is ascii or binary */
    if (*file_type == (ush)UNKNOWN) set_file_type();

    /* Construct the literal and distance trees */
    build_tree((tree_desc near *)(&l_desc));
    Tracev((stderr, "\nlit data: dyn %ld, stat %ld", opt_len, static_len));

    build_tree((tree_desc near *)(&d_desc));
    Tracev((stderr, "\ndist data: dyn %ld, stat %ld", opt_len, static_len));
    /* At this point, opt_len and static_len are the total bit lengths of
     * the compressed block data, excluding the tree representations.
     */

    /* Build the bit length tree for the above two trees, and get the index
     * in bl_order of the last bit length code to send.
     */
    max_blindex = build_bl_tree();

    /* Determine the best encoding. Compute first the block length in bytes */
    opt_lenb = (opt_len+3+7)>>3;
    static_lenb = (static_len+3+7)>>3;
    input_len += stored_len; /* for debugging only */

    Trace((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u dist %u ",
            opt_lenb, opt_len, static_lenb, static_len, stored_len,
            last_lit, last_dist));

    if (static_lenb <= opt_lenb) opt_lenb = static_lenb;

    /* If compression failed and this is the first and last block,
     * and if the zip file can be seeked (to rewrite the local header),
     * the whole file is transformed into a stored file:
     */
#ifdef FORCE_METHOD
#else
    if (stored_len <= opt_lenb && eof && compressed_len == 0L && seekable()) {
#endif
        /* Since LIT_BUFSIZE <= 2*WSIZE, the input data must be there: */
        if (buf == (char*)0) error ("block vanished");

        copy_block(buf, (unsigned)stored_len, 0); /* without header */
        compressed_len = stored_len << 3;
        *file_method = STORED;

#ifdef FORCE_METHOD
#else
    } else if (stored_len+4 <= opt_lenb && buf != (char*)0) {
                       /* 4: two words for the lengths */
#endif
        /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
         * Otherwise we can't have processed more than WSIZE input bytes since
         * the last block flush, because compression would have been
         * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
         * transform a block into a stored block.
         */
        send_bits((STORED_BLOCK<<1)+eof, 3);  /* send block type */
        compressed_len = (compressed_len + 3 + 7) & ~7L;
        compressed_len += (stored_len + 4) << 3;

        copy_block(buf, (unsigned)stored_len, 1); /* with header */

#ifdef FORCE_METHOD
#else
    } else if (static_lenb == opt_lenb) {
#endif
        send_bits((STATIC_TREES<<1)+eof, 3);
        compress_block((ct_data near *)static_ltree, (ct_data near *)static_dtree);
        compressed_len += 3 + static_len;
    } else {
        send_bits((DYN_TREES<<1)+eof, 3);
        send_all_trees(l_desc.max_code+1, d_desc.max_code+1, max_blindex+1);
        compress_block((ct_data near *)dyn_ltree, (ct_data near *)dyn_dtree);
        compressed_len += 3 + opt_len;
    }
    Assert (compressed_len == bits_sent, "bad compressed size");
    init_block();

    if (eof) {
        Assert (input_len == isize, "bad input size");
        bi_windup();
        compressed_len += 7;  /* align on byte boundary */
    }
    Tracev((stderr,"\ncomprlen %lu(%lu) ", compressed_len>>3,
           compressed_len-7*eof));

    return compressed_len >> 3;
}

/* ===========================================================================
 * Save the match info and tally the frequency counts. Return true if
 * the current block must be flushed.
 */
int ct_tally (dist, lc)
    int dist;  /* distance of matched string */
    int lc;    /* match length-MIN_MATCH or unmatched char (if dist==0) */
{
    l_buf[last_lit++] = (uch)lc;
    if (dist == 0) {
        /* lc is the unmatched char */
        dyn_ltree[lc].Freq++;
    } else {
        /* Here, lc is the match length - MIN_MATCH */
        dist--;             /* dist = match distance - 1 */
        Assert((ush)dist < (ush)MAX_DIST &&
               (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
               (ush)d_code(dist) < (ush)D_CODES,  "ct_tally: bad match");

        dyn_ltree[length_code[lc]+LITERALS+1].Freq++;
        dyn_dtree[d_code(dist)].Freq++;

        d_buf[last_dist++] = (ush)dist;
        flags |= flag_bit;
    }
    flag_bit <<= 1;

    /* Output the flags if they fill a byte: */
    if ((last_lit & 7) == 0) {
        flag_buf[last_flags++] = flags;
        flags = 0, flag_bit = 1;
    }
    /* Try to guess if it is profitable to stop the current block here */
    if ((last_lit & 0xfff) == 0) {
        /* Compute an upper bound for the compressed length */
        ulg out_length = (ulg)last_lit*8L;
        ulg in_length = (ulg)strstart-block_start;
        int dcode;
        for (dcode = 0; dcode < D_CODES; dcode++) {
            out_length += (ulg)dyn_dtree[dcode].Freq*(5L+extra_dbits[dcode]);
        }
        out_length >>= 3;
        Trace((stderr,"\nlast_lit %u, last_dist %u, in %ld, out ~%ld(%ld%%) ",
               last_lit, last_dist, in_length, out_length,
               100L - out_length*100L/in_length));
        if (last_dist < last_lit/2 && out_length < in_length/2) return 1;
    }
    return (last_lit == LIT_BUFSIZE-1 || last_dist == DIST_BUFSIZE);
    /* We avoid equality with LIT_BUFSIZE because of wraparound at 64K
     * on 16 bit machines and because stored blocks are restricted to
     * 64K-1 bytes.
     */
}

/* ===========================================================================
 * Send the block data compressed using the given Huffman trees
 */
local void compress_block(ltree, dtree)
    ct_data near *ltree; /* literal tree */
    ct_data near *dtree; /* distance tree */
{
    unsigned dist;      /* distance of matched string */
    int lc;             /* match length or unmatched char (if dist == 0) */
    unsigned lx = 0;    /* running index in l_buf */
    unsigned dx = 0;    /* running index in d_buf */
    unsigned fx = 0;    /* running index in flag_buf */
    uch flag = 0;       /* current flags */
    unsigned code;      /* the code to send */
    int extra;          /* number of extra bits to send */

    if (last_lit != 0) do {
        if ((lx & 7) == 0) flag = flag_buf[fx++];
        lc = l_buf[lx++];
        if ((flag & 1) == 0) {
            send_code(lc, ltree); /* send a literal byte */
            Tracecv(isgraph(lc), (stderr," '%c' ", lc));
        } else {
            /* Here, lc is the match length - MIN_MATCH */
            code = length_code[lc];
            send_code(code+LITERALS+1, ltree); /* send the length code */
            extra = extra_lbits[code];
            if (extra != 0) {
                lc -= base_length[code];
                send_bits(lc, extra);        /* send the extra length bits */
            }
            dist = d_buf[dx++];
            /* Here, dist is the match distance - 1 */
            code = d_code(dist);
            Assert (code < D_CODES, "bad d_code");

            send_code(code, dtree);       /* send the distance code */
            extra = extra_dbits[code];
            if (extra != 0) {
                dist -= base_dist[code];
                send_bits(dist, extra);   /* send the extra distance bits */
            }
        } /* literal or match pair ? */
        flag >>= 1;
    } while (lx < last_lit);

    send_code(END_BLOCK, ltree);
}

/* ===========================================================================
 * Set the file type to ASCII or BINARY, using a crude approximation:
 * binary if more than 20% of the bytes are <= 6 or >= 128, ascii otherwise.
 * IN assertion: the fields freq of dyn_ltree are set and the total of all
 * frequencies does not exceed 64K (to fit in an int on 16 bit machines).
 */
local void set_file_type()
{
    int n = 0;
    unsigned ascii_freq = 0;
    unsigned bin_freq = 0;
    while (n < 7)        bin_freq += dyn_ltree[n++].Freq;
    while (n < 128)    ascii_freq += dyn_ltree[n++].Freq;
    while (n < LITERALS) bin_freq += dyn_ltree[n++].Freq;
    *file_type = bin_freq > (ascii_freq >> 2) ? BINARY : ASCII;
    if (*file_type == BINARY && translate_eol) {
        warn("-l used on binary file", "");
    }
}
/* util.c -- utility functions for gzip support
 * Copyright (C) 1992-1993 Jean-loup Gailly
 * This is free software; you can redistribute it and/or modify it under the
 * terms of the GNU General Public License, see the file COPYING.
 */

#ifdef RCSID
static char rcsid[] = "$Id: gzip.c,v 1.3 1999/10/16 15:48:40 andersen Exp $";
#endif

#include <ctype.h>
#include <errno.h>
#include <sys/types.h>

#ifdef HAVE_UNISTD_H
#  include <unistd.h>
#endif
#ifndef NO_FCNTL_H
#  include <fcntl.h>
#endif

#if defined(STDC_HEADERS) || !defined(NO_STDLIB_H)
#  include <stdlib.h>
#else
   extern int errno;
#endif

extern ulg crc_32_tab[];   /* crc table, defined below */

/* ===========================================================================
 * Copy input to output unchanged: zcat == cat with --force.
 * IN assertion: insize bytes have already been read in inbuf.
 */
int copy(in, out)
    int in, out;   /* input and output file descriptors */
{
    errno = 0;
    while (insize != 0 && (int)insize != EOF) {
        write_buf(out, (char*)inbuf, insize);
        bytes_out += insize;
        insize = read(in, (char*)inbuf, INBUFSIZ);
    }
    if ((int)insize == EOF && errno != 0) {
        read_error();
    }
    bytes_in = bytes_out;
    return OK;
}

/* ========================================================================
 * Put string s in lower case, return s.
 */
char *strlwr(s)
    char *s;
{
    char *t;
    for (t = s; *t; t++) *t = tolow(*t);
    return s;
}

#if defined(NO_STRING_H) && !defined(STDC_HEADERS)

/* Provide missing strspn and strcspn functions. */

#  ifndef __STDC__
#    define const
#  endif

int strspn  OF((const char *s, const char *accept));
int strcspn OF((const char *s, const char *reject));

/* ========================================================================
 * Return the length of the maximum initial segment
 * of s which contains only characters in accept.
 */
int strspn(s, accept)
    const char *s;
    const char *accept;
{
    register const char *p;
    register const char *a;
    register int count = 0;

    for (p = s; *p != '\0'; ++p) {
        for (a = accept; *a != '\0'; ++a) {
            if (*p == *a) break;
        }
        if (*a == '\0') return count;
        ++count;
    }
    return count;
}

/* ========================================================================
 * Return the length of the maximum inital segment of s
 * which contains no characters from reject.
 */
int strcspn(s, reject)
    const char *s;
    const char *reject;
{
    register int count = 0;

    while (*s != '\0') {
        if (strchr(reject, *s++) != NULL) return count;
        ++count;
    }
    return count;
}

#endif /* NO_STRING_H */

/* ========================================================================
 * Add an environment variable (if any) before argv, and update argc.
 * Return the expanded environment variable to be freed later, or NULL 
 * if no options were added to argv.
 */
#define SEPARATOR       " \t"   /* separators in env variable */

char *add_envopt(argcp, argvp, env)
    int *argcp;          /* pointer to argc */
    char ***argvp;       /* pointer to argv */
    char *env;           /* name of environment variable */
{
    char *p;             /* running pointer through env variable */
    char **oargv;        /* runs through old argv array */
    char **nargv;        /* runs through new argv array */
    int  oargc = *argcp; /* old argc */
    int  nargc = 0;      /* number of arguments in env variable */

    env = (char*)getenv(env);
    if (env == NULL) return NULL;

    p = (char*)xmalloc(strlen(env)+1);
    env = strcpy(p, env);                    /* keep env variable intact */

    for (p = env; *p; nargc++ ) {            /* move through env */
        p += strspn(p, SEPARATOR);           /* skip leading separators */
        if (*p == '\0') break;

        p += strcspn(p, SEPARATOR);          /* find end of word */
        if (*p) *p++ = '\0';                 /* mark it */
    }
    if (nargc == 0) {
        free(env);
        return NULL;
    }
    *argcp += nargc;
    /* Allocate the new argv array, with an extra element just in case
     * the original arg list did not end with a NULL.
     */
    nargv = (char**)calloc(*argcp+1, sizeof(char *));
    if (nargv == NULL) error("out of memory");
    oargv  = *argvp;
    *argvp = nargv;

    /* Copy the program name first */
    if (oargc-- < 0) error("argc<=0");
    *(nargv++) = *(oargv++);

    /* Then copy the environment args */
    for (p = env; nargc > 0; nargc--) {
        p += strspn(p, SEPARATOR);           /* skip separators */
        *(nargv++) = p;                      /* store start */
        while (*p++) ;                       /* skip over word */
    }

    /* Finally copy the old args and add a NULL (usual convention) */
    while (oargc--) *(nargv++) = *(oargv++);
    *nargv = NULL;
    return env;
}
/* ========================================================================
 * Display compression ratio on the given stream on 6 characters.
 */
void display_ratio(num, den, file)
    long num;
    long den;
    FILE *file;
{
    long ratio;  /* 1000 times the compression ratio */

    if (den == 0) {
        ratio = 0; /* no compression */
    } else if (den < 2147483L) { /* (2**31 -1)/1000 */
        ratio = 1000L*num/den;
    } else {
        ratio = num/(den/1000L);
    }
    if (ratio < 0) {
        putc('-', file);
        ratio = -ratio;
    } else {
        putc(' ', file);
    }
    fprintf(file, "%2ld.%1ld%%", ratio / 10L, ratio % 10L);
}


/* zip.c -- compress files to the gzip or pkzip format
 * Copyright (C) 1992-1993 Jean-loup Gailly
 * This is free software; you can redistribute it and/or modify it under the
 * terms of the GNU General Public License, see the file COPYING.
 */

#ifdef RCSID
static char rcsid[] = "$Id: gzip.c,v 1.3 1999/10/16 15:48:40 andersen Exp $";
#endif

#include <ctype.h>
#include <sys/types.h>

#ifdef HAVE_UNISTD_H
#  include <unistd.h>
#endif
#ifndef NO_FCNTL_H
#  include <fcntl.h>
#endif

local ulg crc;       /* crc on uncompressed file data */
long header_bytes;   /* number of bytes in gzip header */

/* ===========================================================================
 * Deflate in to out.
 * IN assertions: the input and output buffers are cleared.
 *   The variables time_stamp and save_orig_name are initialized.
 */
int zip(in, out)
    int in, out;            /* input and output file descriptors */
{
    uch  flags = 0;         /* general purpose bit flags */
    ush  attr = 0;          /* ascii/binary flag */
    ush  deflate_flags = 0; /* pkzip -es, -en or -ex equivalent */

    ifd = in;
    ofd = out;
    outcnt = 0;

    /* Write the header to the gzip file. See algorithm.doc for the format */

    method = DEFLATED;
    put_byte(GZIP_MAGIC[0]); /* magic header */
    put_byte(GZIP_MAGIC[1]);
    put_byte(DEFLATED);      /* compression method */

    put_byte(flags);         /* general flags */
    put_long(time_stamp);

    /* Write deflated file to zip file */
    crc = updcrc(0, 0);

    bi_init(out);
    ct_init(&attr, &method);
    lm_init(&deflate_flags);

    put_byte((uch)deflate_flags); /* extra flags */
    put_byte(OS_CODE);            /* OS identifier */

    header_bytes = (long)outcnt;

    (void)deflate();

    /* Write the crc and uncompressed size */
    put_long(crc);
    put_long(isize);
    header_bytes += 2*sizeof(long);

    flush_outbuf();
    return OK;
}


/* ===========================================================================
 * Read a new buffer from the current input file, perform end-of-line
 * translation, and update the crc and input file size.
 * IN assertion: size >= 2 (for end-of-line translation)
 */
int file_read(buf, size)
    char *buf;
    unsigned size;
{
    unsigned len;

    Assert(insize == 0, "inbuf not empty");

    len = read(ifd, buf, size);
    if (len == (unsigned)(-1) || len == 0) return (int)len;

    crc = updcrc((uch*)buf, len);
    isize += (ulg)len;
    return (int)len;
}
#endif