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/* |
* jmemansi.c |
* |
* Copyright (C) 1992-1996, Thomas G. Lane. |
* This file is part of the Independent JPEG Group's software. |
* For conditions of distribution and use, see the accompanying README file. |
* |
* This file provides a simple generic implementation of the system- |
* dependent portion of the JPEG memory manager. This implementation |
* assumes that you have the ANSI-standard library routine tmpfile(). |
* Also, the problem of determining the amount of memory available |
* is shoved onto the user. |
*/ |
|
#define JPEG_INTERNALS |
#include "jinclude.h" |
#include "jpeglib.h" |
#include "jmemsys.h" /* import the system-dependent declarations */ |
|
#ifndef HAVE_STDLIB_H /* <stdlib.h> should declare malloc(),free() */ |
extern void * malloc JPP((size_t size)); |
extern void free JPP((void *ptr)); |
#endif |
|
#ifndef SEEK_SET /* pre-ANSI systems may not define this; */ |
#define SEEK_SET 0 /* if not, assume 0 is correct */ |
#endif |
|
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/* |
* Memory allocation and freeing are controlled by the regular library |
* routines malloc() and free(). |
*/ |
|
GLOBAL(void *) |
jpeg_get_small (j_common_ptr cinfo, size_t sizeofobject) |
{ |
return (void *) malloc(sizeofobject); |
} |
|
GLOBAL(void) |
jpeg_free_small (j_common_ptr cinfo, void * object, size_t sizeofobject) |
{ |
free(object); |
} |
|
|
/* |
* "Large" objects are treated the same as "small" ones. |
* NB: although we include FAR keywords in the routine declarations, |
* this file won't actually work in 80x86 small/medium model; at least, |
* you probably won't be able to process useful-size images in only 64KB. |
*/ |
|
GLOBAL(void FAR *) |
jpeg_get_large (j_common_ptr cinfo, size_t sizeofobject) |
{ |
return (void FAR *) malloc(sizeofobject); |
} |
|
GLOBAL(void) |
jpeg_free_large (j_common_ptr cinfo, void FAR * object, size_t sizeofobject) |
{ |
free(object); |
} |
|
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/* |
* This routine computes the total memory space available for allocation. |
* It's impossible to do this in a portable way; our current solution is |
* to make the user tell us (with a default value set at compile time). |
* If you can actually get the available space, it's a good idea to subtract |
* a slop factor of 5% or so. |
*/ |
|
#ifndef DEFAULT_MAX_MEM /* so can override from makefile */ |
#define DEFAULT_MAX_MEM 1000000L /* default: one megabyte */ |
#endif |
|
GLOBAL(long) |
jpeg_mem_available (j_common_ptr cinfo, long min_bytes_needed, |
long max_bytes_needed, long already_allocated) |
{ |
return cinfo->mem->max_memory_to_use - already_allocated; |
} |
|
|
/* |
* Backing store (temporary file) management. |
* Backing store objects are only used when the value returned by |
* jpeg_mem_available is less than the total space needed. You can dispense |
* with these routines if you have plenty of virtual memory; see jmemnobs.c. |
*/ |
|
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METHODDEF(void) |
read_backing_store (j_common_ptr cinfo, backing_store_ptr info, |
void FAR * buffer_address, |
long file_offset, long byte_count) |
{ |
if (fseek(info->temp_file, file_offset, SEEK_SET)) |
ERREXIT(cinfo, JERR_TFILE_SEEK); |
if (JFREAD(info->temp_file, buffer_address, byte_count) |
!= (size_t) byte_count) |
ERREXIT(cinfo, JERR_TFILE_READ); |
} |
|
|
METHODDEF(void) |
write_backing_store (j_common_ptr cinfo, backing_store_ptr info, |
void FAR * buffer_address, |
long file_offset, long byte_count) |
{ |
if (fseek(info->temp_file, file_offset, SEEK_SET)) |
ERREXIT(cinfo, JERR_TFILE_SEEK); |
if (JFWRITE(info->temp_file, buffer_address, byte_count) |
!= (size_t) byte_count) |
ERREXIT(cinfo, JERR_TFILE_WRITE); |
} |
|
|
METHODDEF(void) |
close_backing_store (j_common_ptr cinfo, backing_store_ptr info) |
{ |
fclose(info->temp_file); |
/* Since this implementation uses tmpfile() to create the file, |
* no explicit file deletion is needed. |
*/ |
} |
|
|
/* |
* Initial opening of a backing-store object. |
* |
* This version uses tmpfile(), which constructs a suitable file name |
* behind the scenes. We don't have to use info->temp_name[] at all; |
* indeed, we can't even find out the actual name of the temp file. |
*/ |
|
GLOBAL(void) |
jpeg_open_backing_store (j_common_ptr cinfo, backing_store_ptr info, |
long total_bytes_needed) |
{ |
if ((info->temp_file = tmpfile()) == NULL) |
ERREXITS(cinfo, JERR_TFILE_CREATE, ""); |
info->read_backing_store = read_backing_store; |
info->write_backing_store = write_backing_store; |
info->close_backing_store = close_backing_store; |
} |
|
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/* |
* These routines take care of any system-dependent initialization and |
* cleanup required. |
*/ |
|
GLOBAL(long) |
jpeg_mem_init (j_common_ptr cinfo) |
{ |
return DEFAULT_MAX_MEM; /* default for max_memory_to_use */ |
} |
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GLOBAL(void) |
jpeg_mem_term (j_common_ptr cinfo) |
{ |
/* no work */ |
} |