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47a0c422ca
libpng/pngmem.c
Andreas Dilger 47a0c422ca Imported from libpng-0.96.tar
2009-04-06 16:04:08 -05:00

312 lines
8.3 KiB
C
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/* pngmem.c - stub functions for memory allocation
libpng 1.0 beta 6 - version 0.96
For conditions of distribution and use, see copyright notice in png.h
Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
Copyright (c) 1996, 1997 Andreas Dilger
May 12, 1997
This file provides a location for all memory allocation. Users which
need special memory handling are expected to modify the code in this file
to meet their needs. See the instructions at each function. */
#define PNG_INTERNAL
#include "png.h"
/* Borland DOS special memory handler */
#if defined(__TURBOC__) && !defined(_Windows) && !defined(__FLAT__)
/* if you change this, be sure to change the one in png.h also */
/* Allocate memory for a png_struct. The malloc and memset can be replaced
by a single call to calloc() if this is thought to improve performance. */
png_voidp
png_create_struct(int type)
{
png_size_t size;
png_voidp struct_ptr;
if (type == PNG_STRUCT_INFO)
size = sizeof(png_info);
else if (type == PNG_STRUCT_PNG)
size = sizeof(png_struct);
else
return (png_voidp)NULL;
if ((struct_ptr = (png_voidp)farmalloc(size)) != NULL)
{
png_memset(struct_ptr, 0, size);
}
return (struct_ptr);
}
/* Free memory allocated by a png_create_struct() call */
void
png_destroy_struct(png_voidp struct_ptr)
{
if (struct_ptr != NULL)
farfree (struct_ptr);
}
/* Allocate memory. For reasonable files, size should never exceed
* 64K. However, zlib may allocate more then 64K if you don't tell
* it not to. See zconf.h and png.h for more information. zlib does
* need to allocate exactly 64K, so whatever you call here must
* have the ability to do that.
*
* Borland seems to have a problem in DOS mode for exactly 64K.
* It gives you a segment with an offset of 8 (perhaps to store it's
* memory stuff). zlib doesn't like this at all, so we have to
* detect and deal with it. This code should not be needed in
* Windows or OS/2 modes, and only in 16 bit mode. This code has
* been updated by Alexander Lehmann for version 0.89 to waste less
* memory.
*
* Note that we can't use png_size_t for the "size" declaration,
* since on some systems a png_size_t is a 16-bit quantity, and as a
* result, we would be truncating potentially larger memory requests
* (which should cause a fatal error) and introducing major problems.
*/
png_voidp
png_malloc(png_structp png_ptr, png_uint_32 size)
{
png_voidp ret;
if (png_ptr == NULL || size == 0)
return ((voidp)NULL);
#ifdef PNG_MAX_MALLOC_64K
if (size > (png_uint_32)65536L)
png_error(png_ptr, "Cannot Allocate > 64K");
#endif
if (size == (png_uint_32)(65536L))
{
if (png_ptr->offset_table == NULL)
{
/* try to see if we need to do any of this fancy stuff */
ret = farmalloc(size);
if (ret == NULL || ((png_size_t)ret & 0xffff))
{
int num_blocks;
png_uint_32 total_size;
png_bytep table;
int i;
png_byte huge * hptr;
if (ret != NULL)
farfree(ret);
ret = NULL;
num_blocks = (int)(1 << (png_ptr->zlib_window_bits - 14));
if (num_blocks < 1)
num_blocks = 1;
if (png_ptr->zlib_mem_level >= 7)
num_blocks += (int)(1 << (png_ptr->zlib_mem_level - 7));
else
num_blocks++;
total_size = ((png_uint_32)65536L) * (png_uint_32)num_blocks+16;
table = farmalloc(total_size);
if (table == NULL)
{
png_error(png_ptr, "Out of Memory");
}
if ((png_size_t)table & 0xfff0)
{
png_error(png_ptr, "Farmalloc didn't return normalized pointer");
}
png_ptr->offset_table = table;
png_ptr->offset_table_ptr = farmalloc(num_blocks *
sizeof (png_bytep));
if (png_ptr->offset_table_ptr == NULL)
{
png_error(png_ptr, "Out of memory");
}
hptr = (png_byte huge *)table;
if ((png_size_t)hptr & 0xf)
{
hptr = (png_byte huge *)((long)(hptr) & 0xfffffff0L);
hptr += 16L;
}
for (i = 0; i < num_blocks; i++)
{
png_ptr->offset_table_ptr[i] = (png_bytep)hptr;
hptr += 65536L;
}
png_ptr->offset_table_number = num_blocks;
png_ptr->offset_table_count = 0;
png_ptr->offset_table_count_free = 0;
}
}
if (png_ptr->offset_table_count >= png_ptr->offset_table_number)
png_error(png_ptr, "Out of Memory");
ret = png_ptr->offset_table_ptr[png_ptr->offset_table_count++];
}
else
ret = farmalloc(size);
if (ret == NULL)
{
png_error(png_ptr, "Out of Memory");
}
return ret;
}
/* free a pointer allocated by png_malloc(). In the default
configuration, png_ptr is not used, but is passed in case it
is needed. If ptr is NULL, return without taking any action. */
void
png_free(png_structp png_ptr, png_voidp ptr)
{
if (png_ptr == NULL || ptr == NULL)
return;
if (png_ptr->offset_table != NULL)
{
int i;
for (i = 0; i < png_ptr->offset_table_count; i++)
{
if (ptr == png_ptr->offset_table_ptr[i])
{
ptr = NULL;
png_ptr->offset_table_count_free++;
break;
}
}
if (png_ptr->offset_table_count_free == png_ptr->offset_table_count)
{
farfree(png_ptr->offset_table);
farfree(png_ptr->offset_table_ptr);
png_ptr->offset_table = NULL;
png_ptr->offset_table_ptr = NULL;
}
}
if (ptr != NULL)
farfree(ptr);
}
#else /* Not the Borland DOS special memory handler */
/* Allocate memory for a png_struct or a png_info. The malloc and
memset can be replaced by a single call to calloc() if this is thought
to improve performance noticably.*/
png_voidp
png_create_struct(int type)
{
png_size_t size;
png_voidp struct_ptr;
if (type == PNG_STRUCT_INFO)
size = sizeof(png_info);
else if (type == PNG_STRUCT_PNG)
size = sizeof(png_struct);
else
return (png_voidp)NULL;
#if defined(__TURBOC__) && !defined(__FLAT__)
if ((struct_ptr = (png_voidp)farmalloc(size)) != NULL)
#else
# if defined(_MSC_VER) && defined(MAXSEG_64K)
if ((struct_ptr = (png_voidp)halloc(size,1)) != NULL)
# else
if ((struct_ptr = (png_voidp)malloc(size)) != NULL)
# endif
#endif
{
png_memset(struct_ptr, 0, size);
}
return (struct_ptr);
}
/* Free memory allocated by a png_create_struct() call */
void
png_destroy_struct(png_voidp struct_ptr)
{
if (struct_ptr != NULL)
#if defined(__TURBOC__) && !defined(__FLAT__)
farfree(struct_ptr);
#else
# if defined(_MSC_VER) && defined(MAXSEG_64K)
hfree(struct_ptr);
# else
free(struct_ptr);
# endif
#endif
}
/* Allocate memory. For reasonable files, size should never exceed
64K. However, zlib may allocate more then 64K if you don't tell
it not to. See zconf.h and png.h for more information. zlib does
need to allocate exactly 64K, so whatever you call here must
have the ability to do that. */
png_voidp
png_malloc(png_structp png_ptr, png_uint_32 size)
{
png_voidp ret;
if (png_ptr == NULL || size == 0)
return (NULL);
#ifdef PNG_MAX_MALLOC_64K
if (size > (png_uint_32)65536L)
png_error(png_ptr, "Cannot Allocate > 64K");
#endif
#if defined(__TURBOC__) && !defined(__FLAT__)
ret = farmalloc((png_size_t)size);
#else
# if defined(_MSC_VER) && defined(MAXSEG_64K)
ret = halloc(size, 1);
# else
ret = malloc(size);
# endif
#endif
if (ret == NULL)
{
png_error(png_ptr, "Out of Memory");
}
return ret;
}
/* Free a pointer allocated by png_malloc(). In the default
configuration, png_ptr is not used, but is passed in case it
is needed. If ptr is NULL, return without taking any action. */
void
png_free(png_structp png_ptr, png_voidp ptr)
{
if (png_ptr == NULL || ptr == NULL)
return;
#if defined(__TURBOC__) && !defined(__FLAT__)
farfree(ptr);
#else
# if defined(_MSC_VER) && defined(MAXSEG_64K)
hfree(ptr);
# else
free(ptr);
# endif
#endif
}
#endif /* Not Borland DOS special memory handler */
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