| 1 | /* |
| 2 | * jmemansi.c |
| 3 | * |
| 4 | * Copyright (C) 1992-1996, Thomas G. Lane. |
| 5 | * This file is part of the Independent JPEG Group's software. |
| 6 | * For conditions of distribution and use, see the accompanying README file. |
| 7 | * |
| 8 | * This file provides a simple generic implementation of the system- |
| 9 | * dependent portion of the JPEG memory manager. This implementation |
| 10 | * assumes that you have the ANSI-standard library routine tmpfile(). |
| 11 | * Also, the problem of determining the amount of memory available |
| 12 | * is shoved onto the user. |
| 13 | */ |
| 14 | |
| 15 | #define JPEG_INTERNALS |
| 16 | #include "jinclude.h" |
| 17 | #include "jpeglib.h" |
| 18 | #include "jmemsys.h" /* import the system-dependent declarations */ |
| 19 | |
| 20 | #ifndef HAVE_STDLIB_H /* <stdlib.h> should declare malloc(),free() */ |
| 21 | extern void * malloc JPP((size_t size)); |
| 22 | extern void free JPP((void *ptr)); |
| 23 | #endif |
| 24 | |
| 25 | #ifndef SEEK_SET /* pre-ANSI systems may not define this; */ |
| 26 | #define SEEK_SET 0 /* if not, assume 0 is correct */ |
| 27 | #endif |
| 28 | |
| 29 | |
| 30 | /* |
| 31 | * Memory allocation and freeing are controlled by the regular library |
| 32 | * routines malloc() and free(). |
| 33 | */ |
| 34 | |
| 35 | GLOBAL(void *) |
| 36 | jpeg_get_small (j_common_ptr cinfo, size_t sizeofobject) |
| 37 | { |
| 38 | return (void *) malloc(sizeofobject); |
| 39 | } |
| 40 | |
| 41 | GLOBAL(void) |
| 42 | jpeg_free_small (j_common_ptr cinfo, void * object, size_t sizeofobject) |
| 43 | { |
| 44 | free(object); |
| 45 | } |
| 46 | |
| 47 | |
| 48 | /* |
| 49 | * "Large" objects are treated the same as "small" ones. |
| 50 | * NB: although we include FAR keywords in the routine declarations, |
| 51 | * this file won't actually work in 80x86 small/medium model; at least, |
| 52 | * you probably won't be able to process useful-size images in only 64KB. |
| 53 | */ |
| 54 | |
| 55 | GLOBAL(void FAR *) |
| 56 | jpeg_get_large (j_common_ptr cinfo, size_t sizeofobject) |
| 57 | { |
| 58 | return (void FAR *) malloc(sizeofobject); |
| 59 | } |
| 60 | |
| 61 | GLOBAL(void) |
| 62 | jpeg_free_large (j_common_ptr cinfo, void FAR * object, size_t sizeofobject) |
| 63 | { |
| 64 | free(object); |
| 65 | } |
| 66 | |
| 67 | |
| 68 | /* |
| 69 | * This routine computes the total memory space available for allocation. |
| 70 | * It's impossible to do this in a portable way; our current solution is |
| 71 | * to make the user tell us (with a default value set at compile time). |
| 72 | * If you can actually get the available space, it's a good idea to subtract |
| 73 | * a slop factor of 5% or so. |
| 74 | */ |
| 75 | |
| 76 | #ifndef DEFAULT_MAX_MEM /* so can override from makefile */ |
| 77 | #define DEFAULT_MAX_MEM 1000000L /* default: one megabyte */ |
| 78 | #endif |
| 79 | |
| 80 | GLOBAL(long) |
| 81 | jpeg_mem_available (j_common_ptr cinfo, long min_bytes_needed, |
| 82 | long max_bytes_needed, long already_allocated) |
| 83 | { |
| 84 | return cinfo->mem->max_memory_to_use - already_allocated; |
| 85 | } |
| 86 | |
| 87 | |
| 88 | /* |
| 89 | * Backing store (temporary file) management. |
| 90 | * Backing store objects are only used when the value returned by |
| 91 | * jpeg_mem_available is less than the total space needed. You can dispense |
| 92 | * with these routines if you have plenty of virtual memory; see jmemnobs.c. |
| 93 | */ |
| 94 | |
| 95 | |
| 96 | METHODDEF(void) |
| 97 | read_backing_store (j_common_ptr cinfo, backing_store_ptr info, |
| 98 | void FAR * buffer_address, |
| 99 | long file_offset, long byte_count) |
| 100 | { |
| 101 | if (fseek(info->temp_file, file_offset, SEEK_SET)) |
| 102 | ERREXIT(cinfo, JERR_TFILE_SEEK); |
| 103 | if (JFREAD(info->temp_file, buffer_address, byte_count) |
| 104 | != (size_t) byte_count) |
| 105 | ERREXIT(cinfo, JERR_TFILE_READ); |
| 106 | } |
| 107 | |
| 108 | |
| 109 | METHODDEF(void) |
| 110 | write_backing_store (j_common_ptr cinfo, backing_store_ptr info, |
| 111 | void FAR * buffer_address, |
| 112 | long file_offset, long byte_count) |
| 113 | { |
| 114 | if (fseek(info->temp_file, file_offset, SEEK_SET)) |
| 115 | ERREXIT(cinfo, JERR_TFILE_SEEK); |
| 116 | if (JFWRITE(info->temp_file, buffer_address, byte_count) |
| 117 | != (size_t) byte_count) |
| 118 | ERREXIT(cinfo, JERR_TFILE_WRITE); |
| 119 | } |
| 120 | |
| 121 | |
| 122 | METHODDEF(void) |
| 123 | close_backing_store (j_common_ptr cinfo, backing_store_ptr info) |
| 124 | { |
| 125 | fclose(info->temp_file); |
| 126 | /* Since this implementation uses tmpfile() to create the file, |
| 127 | * no explicit file deletion is needed. |
| 128 | */ |
| 129 | } |
| 130 | |
| 131 | |
| 132 | /* |
| 133 | * Initial opening of a backing-store object. |
| 134 | * |
| 135 | * This version uses tmpfile(), which constructs a suitable file name |
| 136 | * behind the scenes. We don't have to use info->temp_name[] at all; |
| 137 | * indeed, we can't even find out the actual name of the temp file. |
| 138 | */ |
| 139 | |
| 140 | GLOBAL(void) |
| 141 | jpeg_open_backing_store (j_common_ptr cinfo, backing_store_ptr info, |
| 142 | long total_bytes_needed) |
| 143 | { |
| 144 | if ((info->temp_file = tmpfile()) == NULL) |
| 145 | ERREXITS(cinfo, JERR_TFILE_CREATE, ""); |
| 146 | info->read_backing_store = read_backing_store; |
| 147 | info->write_backing_store = write_backing_store; |
| 148 | info->close_backing_store = close_backing_store; |
| 149 | } |
| 150 | |
| 151 | |
| 152 | /* |
| 153 | * These routines take care of any system-dependent initialization and |
| 154 | * cleanup required. |
| 155 | */ |
| 156 | |
| 157 | GLOBAL(long) |
| 158 | jpeg_mem_init (j_common_ptr cinfo) |
| 159 | { |
| 160 | return DEFAULT_MAX_MEM; /* default for max_memory_to_use */ |
| 161 | } |
| 162 | |
| 163 | GLOBAL(void) |
| 164 | jpeg_mem_term (j_common_ptr cinfo) |
| 165 | { |
| 166 | /* no work */ |
| 167 | } |