ZLIB DATA COMPRESSION LIBRARY

zlib 1.2.11 is a general purpose data compression library.  All the code is
thread safe.  The data format used by the zlib library is described by RFCs
(Request for Comments) 1950 to 1952 in the files
http://tools.ietf.org/html/rfc1950 (zlib format), rfc1951 (deflate format) and
rfc1952 (gzip format).

All functions of the compression library are documented in the file zlib.h
(volunteer to write man pages welcome, contact zlib@gzip.org).  A usage example
of the library is given in the file test/example.c which also tests that
the library is working correctly.  Another example is given in the file
test/minigzip.c.  The compression library itself is composed of all source
files in the root directory.

To compile all files and run the test program, follow the instructions given at
the top of Makefile.in.  In short "./configure; make test", and if that goes
well, "make install" should work for most flavors of Unix.  For Windows, use
one of the special makefiles in win32/ or contrib/vstudio/ .  For VMS, use
make_vms.com.

Questions about zlib should be sent to <zlib@gzip.org>, or to Gilles Vollant
<info@winimage.com> for the Windows DLL version.  The zlib home page is
http://zlib.net/ .  Before reporting a problem, please check this site to
verify that you have the latest version of zlib; otherwise get the latest
version and check whether the problem still exists or not.

PLEASE read the zlib FAQ http://zlib.net/zlib_faq.html before asking for help.

Mark Nelson <markn@ieee.org> wrote an article about zlib for the Jan.  1997
issue of Dr.  Dobb's Journal; a copy of the article is available at
http://marknelson.us/1997/01/01/zlib-engine/ .

The changes made in version 1.2.11 are documented in the file ChangeLog.

Unsupported third party contributions are provided in directory contrib/ .

zlib is available in Java using the java.util.zip package, documented at
http://java.sun.com/developer/technicalArticles/Programming/compression/ .

A Perl interface to zlib written by Paul Marquess <pmqs@cpan.org> is available
at CPAN (Comprehensive Perl Archive Network) sites, including
http://search.cpan.org/~pmqs/IO-Compress-Zlib/ .

A Python interface to zlib written by A.M. K
/* zutil.c -- target dependent utility functions for the compression library
 * Copyright (C) 1995-2017 Jean-loup Gailly
 * For conditions of distribution and use, see copyright notice in zlib.h
 */

/* @(#) $Id$ */

#include "zutil.h"
#ifndef Z_SOLO
#  include "gzguts.h"
#endif

z_const char * const z_errmsg[10] = {
    (z_const char *)"need dictionary",     /* Z_NEED_DICT       2  */
    (z_const char *)"stream end",          /* Z_STREAM_END      1  */
    (z_const char *)"",                    /* Z_OK              0  */
    (z_const char *)"file error",          /* Z_ERRNO         (-1) */
    (z_const char *)"stream error",        /* Z_STREAM_ERROR  (-2) */
    (z_const char *)"data error",          /* Z_DATA_ERROR    (-3) */
    (z_const char *)"insufficient memory", /* Z_MEM_ERROR     (-4) */
    (z_const char *)"buffer error",        /* Z_BUF_ERROR     (-5) */
    (z_const char *)"incompatible version",/* Z_VERSION_ERROR (-6) */
    (z_const char *)""
};


const char * ZEXPORT zlibVersion()
{
    return ZLIB_VERSION;
}

uLong ZEXPORT zlibCompileFlags()
{
    uLong flags;

    flags = 0;
    switch ((int)(sizeof(uInt))) {
    case 2:     break;
    case 4:     flags += 1;     break;
    case 8:     flags += 2;     break;
    default:    flags += 3;
    }
    switch ((int)(sizeof(uLong))) {
    case 2:     break;
    case 4:     flags += 1 << 2;        break;
    case 8:     flags += 2 << 2;        break;
    default:    flags += 3 << 2;
    }
    switch ((int)(sizeof(voidpf))) {
    case 2:     break;
    case 4:     flags += 1 << 4;        break;
    case 8:     flags += 2 << 4;        break;
    default:    flags += 3 << 4;
    }
    switch ((int)(sizeof(z_off_t))) {
    case 2:     break;
    case 4:     flags += 1 << 6;        break;
    case 8:     flags += 2 << 6;        break;
    default:    flags += 3 << 6;
    }
#ifdef ZLIB_DEBUG
    flags += 1 << 8;
#endif
#if defined(ASMV) || defined(ASMINF)
    flags += 1 << 9;
#endif
#ifdef ZLIB_WINAPI
    flags += 1 << 10;
#endif
#ifdef BUILDFIXED
    flags += 1 << 12;
#endif
#ifdef DYNAMIC_CRC_TABLE
    flags += 1 << 13;
#endif
#ifdef NO_GZCOMPRESS
    flags += 1L << 16;
#endif
#ifdef NO_GZIP
    flags += 1L << 17;
#endif
#ifdef PKZIP_BUG_WORKAROUND
    flags += 1L << 20;
#endif
#ifdef FASTEST
    flags += 1L << 21;
#endif
#if defined(STDC) || defined(Z_HAVE_STDARG_H)
#  ifdef NO_vsnprintf
    flags += 1L << 25;
#    ifdef HAS_vsprintf_void
    flags += 1L << 26;
#    endif
#  else
#    ifdef HAS_vsnprintf_void
    flags += 1L << 26;
#    endif
#  endif
#else
    flags += 1L << 24;
#  ifdef NO_snprintf
    flags += 1L << 25;
#    ifdef HAS_sprintf_void
    flags += 1L << 26;
#    endif
#  else
#    ifdef HAS_snprintf_void
    flags += 1L << 26;
#    endif
#  endif
#endif
    return flags;
}

#ifdef ZLIB_DEBUG
#include <stdlib.h>
#  ifndef verbose
#    define verbose 0
#  endif
int ZLIB_INTERNAL z_verbose = verbose;

void ZLIB_INTERNAL z_error (m)
    char *m;
{
    fprintf(stderr, "%s\n", m);
    exit(1);
}
#endif

/* exported to allow conversion of error code to string for compress() and
 * uncompress()
 */
const char * ZEXPORT zError(err)
    int err;
{
    return ERR_MSG(err);
}

#if defined(_WIN32_WCE)
    /* The Microsoft C Run-Time Library for Windows CE doesn't have
     * errno.  We define it as a global variable to simplify porting.
     * Its value is always 0 and should not be used.
     */
    int errno = 0;
#endif

#ifndef HAVE_MEMCPY

void ZLIB_INTERNAL zmemcpy(dest, source, len)
    Bytef* dest;
    const Bytef* source;
    uInt  len;
{
    if (len == 0) return;
    do {
        *dest++ = *source++; /* ??? to be unrolled */
    } while (--len != 0);
}

int ZLIB_INTERNAL zmemcmp(s1, s2, len)
    const Bytef* s1;
    const Bytef* s2;
    uInt  len;
{
    uInt j;

    for (j = 0; j < len; j++) {
        if (s1[j] != s2[j]) return 2*(s1[j] > s2[j])-1;
    }
    return 0;
}

void ZLIB_INTERNAL zmemzero(dest, len)
    Bytef* dest;
    uInt  len;
{
    if (len == 0) return;
    do {
        *dest++ = 0;  /* ??? to be unrolled */
    } while (--len != 0);
}
#endif

#ifndef Z_SOLO

#ifdef SYS16BIT

#ifdef __TURBOC__
/* Turbo C in 16-bit mode */

#  define MY_ZCALLOC

/* Turbo C malloc() does not allow dynamic allocation of 64K bytes
 * and farmalloc(64K) returns a pointer with an offset of 8, so we
 * must fix the pointer. Warning: the pointer must be put back to its
 * original form in order to free it, use zcfree().
 */

#define MAX_PTR 10
/* 10*64K = 640K */

local int next_ptr = 0;

typedef struct ptr_table_s {
    voidpf org_ptr;
    voidpf new_ptr;
} ptr_table;

local ptr_table table[MAX_PTR];
/* This table is used to remember the original form of pointers
 * to large buffers (64K). Such pointers are normalized with a zero offset.
 * Since MSDOS is not a preemptive multitasking OS, this table is not
 * protected from concurrent access. This hack doesn't work anyway on
 * a protected system like OS/2. Use Microsoft C instead.
 */

voidpf ZLIB_INTERNAL zcalloc (voidpf opaque, unsigned items, unsigned size)
{
    voidpf buf;
    ulg bsize = (ulg)items*size;

    (void)opaque;

    /* If we allocate less than 65520 bytes, we assume that farmalloc
     * will return a usable pointer which doesn't have to be normalized.
     */
    if (bsize < 65520L) {
        buf = farmalloc(bsize);
        if (*(ush*)&buf != 0) return buf;
    } else {
        buf = farmalloc(bsize + 16L);
    }
    if (buf == NULL || next_ptr >= MAX_PTR) return NULL;
    table[next_ptr].org_ptr = buf;

    /* Normalize the pointer to seg:0 */
    *((ush*)&buf+1) += ((ush)((uch*)buf-0) + 15) >> 4;
    *(ush*)&buf = 0;
    table[next_ptr++].new_ptr = buf;
    return buf;
}

void ZLIB_INTERNAL zcfree (voidpf opaque, voidpf ptr)
{
    int n;

    (void)opaque;

    if (*(ush*)&ptr != 0) { /* object < 64K */
        farfree(ptr);
        return;
    }
    /* Find the original pointer */
    for (n = 0; n < next_ptr; n++) {
        if (ptr != table[n].new_ptr) continue;

        farfree(table[n].org_ptr);
        while (++n < next_ptr) {
            table[n-1] = table[n];
        }
        next_ptr--;
        return;
    }
    Assert(0, "zcfree: ptr not found");
}

#endif /* __TURBOC__ */


#ifdef M_I86
/* Microsoft C in 16-bit mode */

#  define MY_ZCALLOC

#if (!defined(_MSC_VER) || (_MSC_VER <= 600))
#  define _halloc  halloc
#  define _hfree   hfree
#endif

voidpf ZLIB_INTERNAL zcalloc (voidpf opaque, uInt items, uInt size)
{
    (void)opaque;
    return _halloc((long)items, size);
}

void ZLIB_INTERNAL zcfree (voidpf opaque, voidpf ptr)
{
    (void)opaque;
    _hfree(ptr);
}

#endif /* M_I86 */

#endif /* SYS16BIT */


#ifndef MY_ZCALLOC /* Any system without a special alloc function */

#ifndef STDC
extern voidp  malloc OF((uInt size));
extern voidp  calloc OF((uInt items, uInt size));
extern void   free   OF((voidpf ptr));
#endif

voidpf ZLIB_INTERNAL zcalloc (opaque, items, size)
    voidpf opaque;
    unsigned items;
    unsigned size;
{
    (void)opaque;
    return sizeof(uInt) > 2 ? (voidpf)malloc(items * size) :
                              (voidpf)calloc(items, size);
}

void ZLIB_INTERNAL zcfree (opaque, ptr)
    voidpf opaque;
    voidpf ptr;
{
    (void)opaque;
    free(ptr);
}

#endif /* MY_ZCALLOC */

#endif /* !Z_SOLO */