/* * jmemansi.c * * Copyright (C) 1992-1994, 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 */ }