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| 1 /* | |
| 2 * jmemsys.h | |
| 3 * | |
| 4 * Copyright (C) 1992-1997, 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 include file defines the interface between the system-independent | |
| 9 * and system-dependent portions of the JPEG memory manager. No other | |
| 10 * modules need include it. (The system-independent portion is jmemmgr.c; | |
| 11 * there are several different versions of the system-dependent portion.) | |
| 12 * | |
| 13 * This file works as-is for the system-dependent memory managers supplied | |
| 14 * in the IJG distribution. You may need to modify it if you write a | |
| 15 * custom memory manager. If system-dependent changes are needed in | |
| 16 * this file, the best method is to #ifdef them based on a configuration | |
| 17 * symbol supplied in jconfig.h, as we have done with USE_MSDOS_MEMMGR | |
| 18 * and USE_MAC_MEMMGR. | |
| 19 */ | |
| 20 | |
| 21 | |
| 22 /* Short forms of external names for systems with brain-damaged linkers. */ | |
| 23 | |
| 24 #ifdef NEED_SHORT_EXTERNAL_NAMES | |
| 25 #define jpeg_get_small jGetSmall | |
| 26 #define jpeg_free_small jFreeSmall | |
| 27 #define jpeg_get_large jGetLarge | |
| 28 #define jpeg_free_large jFreeLarge | |
| 29 #define jpeg_mem_available jMemAvail | |
| 30 #define jpeg_open_backing_store jOpenBackStore | |
| 31 #define jpeg_mem_init jMemInit | |
| 32 #define jpeg_mem_term jMemTerm | |
| 33 #endif /* NEED_SHORT_EXTERNAL_NAMES */ | |
| 34 | |
| 35 | |
| 36 /* | |
| 37 * These two functions are used to allocate and release small chunks of | |
| 38 * memory. (Typically the total amount requested through jpeg_get_small is | |
| 39 * no more than 20K or so; this will be requested in chunks of a few K each.) | |
| 40 * Behavior should be the same as for the standard library functions malloc | |
| 41 * and free; in particular, jpeg_get_small must return NULL on failure. | |
| 42 * On most systems, these ARE malloc and free. jpeg_free_small is passed the | |
| 43 * size of the object being freed, just in case it's needed. | |
| 44 * On an 80x86 machine using small-data memory model, these manage near heap. | |
| 45 */ | |
| 46 | |
| 47 EXTERN(void *) jpeg_get_small JPP((j_common_ptr cinfo, size_t sizeofobject)); | |
| 48 EXTERN(void) jpeg_free_small JPP((j_common_ptr cinfo, void * object, | |
| 49 size_t sizeofobject)); | |
| 50 | |
| 51 /* | |
| 52 * These two functions are used to allocate and release large chunks of | |
| 53 * memory (up to the total free space designated by jpeg_mem_available). | |
| 54 * The interface is the same as above, except that on an 80x86 machine, | |
| 55 * far pointers are used. On most other machines these are identical to | |
| 56 * the jpeg_get/free_small routines; but we keep them separate anyway, | |
| 57 * in case a different allocation strategy is desirable for large chunks. | |
| 58 */ | |
| 59 | |
| 60 EXTERN(void FAR *) jpeg_get_large JPP((j_common_ptr cinfo, | |
| 61 size_t sizeofobject)); | |
| 62 EXTERN(void) jpeg_free_large JPP((j_common_ptr cinfo, void FAR * object, | |
| 63 size_t sizeofobject)); | |
| 64 | |
| 65 /* | |
| 66 * The macro MAX_ALLOC_CHUNK designates the maximum number of bytes that may | |
| 67 * be requested in a single call to jpeg_get_large (and jpeg_get_small for that | |
| 68 * matter, but that case should never come into play). This macro is needed | |
| 69 * to model the 64Kb-segment-size limit of far addressing on 80x86 machines. | |
| 70 * On those machines, we expect that jconfig.h will provide a proper value. | |
| 71 * On machines with 32-bit flat address spaces, any large constant may be used. | |
| 72 * | |
| 73 * NB: jmemmgr.c expects that MAX_ALLOC_CHUNK will be representable as type | |
| 74 * size_t and will be a multiple of sizeof(align_type). | |
| 75 */ | |
| 76 | |
| 77 #ifndef MAX_ALLOC_CHUNK /* may be overridden in jconfig.h */ | |
| 78 #define MAX_ALLOC_CHUNK 1000000000L | |
| 79 #endif | |
| 80 | |
| 81 /* | |
| 82 * This routine computes the total space still available for allocation by | |
| 83 * jpeg_get_large. If more space than this is needed, backing store will be | |
| 84 * used. NOTE: any memory already allocated must not be counted. | |
| 85 * | |
| 86 * There is a minimum space requirement, corresponding to the minimum | |
| 87 * feasible buffer sizes; jmemmgr.c will request that much space even if | |
| 88 * jpeg_mem_available returns zero. The maximum space needed, enough to hold | |
| 89 * all working storage in memory, is also passed in case it is useful. | |
| 90 * Finally, the total space already allocated is passed. If no better | |
| 91 * method is available, cinfo->mem->max_memory_to_use - already_allocated | |
| 92 * is often a suitable calculation. | |
| 93 * | |
| 94 * It is OK for jpeg_mem_available to underestimate the space available | |
| 95 * (that'll just lead to more backing-store access than is really necessary). | |
| 96 * However, an overestimate will lead to failure. Hence it's wise to subtract | |
| 97 * a slop factor from the true available space. 5% should be enough. | |
| 98 * | |
| 99 * On machines with lots of virtual memory, any large constant may be returned. | |
| 100 * Conversely, zero may be returned to always use the minimum amount of memory. | |
| 101 */ | |
| 102 | |
| 103 EXTERN(long) jpeg_mem_available JPP((j_common_ptr cinfo, | |
| 104 long min_bytes_needed, | |
| 105 long max_bytes_needed, | |
| 106 long already_allocated)); | |
| 107 | |
| 108 | |
| 109 /* | |
| 110 * This structure holds whatever state is needed to access a single | |
| 111 * backing-store object. The read/write/close method pointers are called | |
| 112 * by jmemmgr.c to manipulate the backing-store object; all other fields | |
| 113 * are private to the system-dependent backing store routines. | |
| 114 */ | |
| 115 | |
| 116 #define TEMP_NAME_LENGTH 64 /* max length of a temporary file's name */ | |
| 117 | |
| 118 | |
| 119 #ifdef USE_MSDOS_MEMMGR /* DOS-specific junk */ | |
| 120 | |
| 121 typedef unsigned short XMSH; /* type of extended-memory handles */ | |
| 122 typedef unsigned short EMSH; /* type of expanded-memory handles */ | |
| 123 | |
| 124 typedef union { | |
| 125 short file_handle; /* DOS file handle if it's a temp file */ | |
| 126 XMSH xms_handle; /* handle if it's a chunk of XMS */ | |
| 127 EMSH ems_handle; /* handle if it's a chunk of EMS */ | |
| 128 } handle_union; | |
| 129 | |
| 130 #endif /* USE_MSDOS_MEMMGR */ | |
| 131 | |
| 132 #ifdef USE_MAC_MEMMGR /* Mac-specific junk */ | |
| 133 #include <Files.h> | |
| 134 #endif /* USE_MAC_MEMMGR */ | |
| 135 | |
| 136 | |
| 137 typedef struct backing_store_struct * backing_store_ptr; | |
| 138 | |
| 139 typedef struct backing_store_struct { | |
| 140 /* Methods for reading/writing/closing this backing-store object */ | |
| 141 JMETHOD(void, read_backing_store, (j_common_ptr cinfo, | |
| 142 backing_store_ptr info, | |
| 143 void FAR * buffer_address, | |
| 144 long file_offset, long byte_count)); | |
| 145 JMETHOD(void, write_backing_store, (j_common_ptr cinfo, | |
| 146 backing_store_ptr info, | |
| 147 void FAR * buffer_address, | |
| 148 long file_offset, long byte_count)); | |
| 149 JMETHOD(void, close_backing_store, (j_common_ptr cinfo, | |
| 150 backing_store_ptr info)); | |
| 151 | |
| 152 /* Private fields for system-dependent backing-store management */ | |
| 153 #ifdef USE_MSDOS_MEMMGR | |
| 154 /* For the MS-DOS manager (jmemdos.c), we need: */ | |
| 155 handle_union handle; /* reference to backing-store storage object */ | |
| 156 char temp_name[TEMP_NAME_LENGTH]; /* name if it's a file */ | |
| 157 #else | |
| 158 #ifdef USE_MAC_MEMMGR | |
| 159 /* For the Mac manager (jmemmac.c), we need: */ | |
| 160 short temp_file; /* file reference number to temp file */ | |
| 161 FSSpec tempSpec; /* the FSSpec for the temp file */ | |
| 162 char temp_name[TEMP_NAME_LENGTH]; /* name if it's a file */ | |
| 163 #else | |
| 164 /* For a typical implementation with temp files, we need: */ | |
| 165 FILE * temp_file; /* stdio reference to temp file */ | |
| 166 char temp_name[TEMP_NAME_LENGTH]; /* name of temp file */ | |
| 167 #endif | |
| 168 #endif | |
| 169 } backing_store_info; | |
| 170 | |
| 171 | |
| 172 /* | |
| 173 * Initial opening of a backing-store object. This must fill in the | |
| 174 * read/write/close pointers in the object. The read/write routines | |
| 175 * may take an error exit if the specified maximum file size is exceeded. | |
| 176 * (If jpeg_mem_available always returns a large value, this routine can | |
| 177 * just take an error exit.) | |
| 178 */ | |
| 179 | |
| 180 EXTERN(void) jpeg_open_backing_store JPP((j_common_ptr cinfo, | |
| 181 backing_store_ptr info, | |
| 182 long total_bytes_needed)); | |
| 183 | |
| 184 | |
| 185 /* | |
| 186 * These routines take care of any system-dependent initialization and | |
| 187 * cleanup required. jpeg_mem_init will be called before anything is | |
| 188 * allocated (and, therefore, nothing in cinfo is of use except the error | |
| 189 * manager pointer). It should return a suitable default value for | |
| 190 * max_memory_to_use; this may subsequently be overridden by the surrounding | |
| 191 * application. (Note that max_memory_to_use is only important if | |
| 192 * jpeg_mem_available chooses to consult it ... no one else will.) | |
| 193 * jpeg_mem_term may assume that all requested memory has been freed and that | |
| 194 * all opened backing-store objects have been closed. | |
| 195 */ | |
| 196 | |
| 197 EXTERN(long) jpeg_mem_init JPP((j_common_ptr cinfo)); | |
| 198 EXTERN(void) jpeg_mem_term JPP((j_common_ptr cinfo)); | |
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Chromium Code Reviews
Issue 1705523002:
Remove libjpeg and libjpeg_turbo. (Closed)
Base URL: https://github.com/domokit/mojo.git@master