/* | |
* 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 | |
/* | |
* 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); | |
} | |
/* | |
* 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. | |
*/ | |
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; | |
} | |
/* | |
* 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 */ | |
} | |
GLOBAL(void) | |
jpeg_mem_term (j_common_ptr cinfo) | |
{ | |
/* no work */ | |
} |