/* zutil.c -- target dependent utility functions for the compression library

 * Copyright (C) 1995-2002 Jean-loup Gailly.

 * For conditions of distribution and use, see copyright notice in zlib.h

 */

/* @(#) $Id$ */

#include "zutil.h"

#ifndef STDC

extern void exit OF((int));

#endif

#ifndef HAVE_MEMCPY

void 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 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 zmemzero(dest, len)

    Bytef* dest;

    uInt  len;

{

    if (len == 0) return;

    do {

        *dest++ = 0;  /* ??? to be unrolled */

    } while (--len != 0);

}

#endif

#if defined( MSDOS ) && defined( __TURBOC__ ) && !defined( MY_ZCALLOC )

#if (defined( __BORLANDC__) || !defined(SMALL_MEDIUM)) && !defined(__32BIT__)

/* Small and medium model in Turbo C are for now limited to near allocation

 * with reduced MAX_WBITS and MAX_MEM_LEVEL

 */

#  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 zcalloc (voidpf opaque, unsigned items, unsigned size)

{

    voidpf buf = opaque; /* just to make some compilers happy */

    ulg bsize = (ulg)items*size;

    /* 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  zcfree (voidpf opaque, voidpf ptr)

{

    int n;

    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;

    }

    ptr = opaque; /* just to make some compilers happy */

    Assert(0, "zcfree: ptr not found");

}

#endif

#endif /* MSDOS && __TURBOC__ */

#if defined(M_I86) && !defined(__32BIT__) && !defined( MY_ZCALLOC )

/* Microsoft C in 16-bit mode */

#  define MY_ZCALLOC

#if (!defined(_MSC_VER) || (_MSC_VER <= 600))

#  define _halloc  halloc

#  define _hfree   hfree

#endif

voidpf zcalloc (voidpf opaque, unsigned items, unsigned size)

{

    if (opaque) opaque = 0; /* to make compiler happy */

    return _halloc((long)items, size);

}

void  zcfree (voidpf opaque, voidpf ptr)

{

    if (opaque) opaque = 0; /* to make compiler happy */

    _hfree(ptr);

}

#endif /* MSC */

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

#ifndef STDC

extern voidp  ft_scalloc OF((uInt items, uInt size));

extern void   ft_sfree   OF((voidpf ptr));

#endif

voidpf zcalloc (opaque, items, size)

    voidpf opaque;

    unsigned items;

    unsigned size;

{

    if (opaque) items += size - size; /* make compiler happy */

    return (voidpf)ft_scalloc(items, size);

}

void  zcfree (opaque, ptr)

    voidpf opaque;

    voidpf ptr;

{

    ft_sfree(ptr);

    if (opaque) return; /* make compiler happy */

}

#endif /* MY_ZCALLOC */