Thomas G. Lane | 4a6b730 | 1992-03-17 00:00:00 +0000 | [diff] [blame] | 1 | /* |
| 2 | * jmemsys.h |
| 3 | * |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame^] | 4 | * Copyright (C) 1992-1994, Thomas G. Lane. |
Thomas G. Lane | 4a6b730 | 1992-03-17 00:00:00 +0000 | [diff] [blame] | 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 |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame^] | 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.) |
Thomas G. Lane | 4a6b730 | 1992-03-17 00:00:00 +0000 | [diff] [blame] | 12 | * |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame^] | 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. |
Thomas G. Lane | 4a6b730 | 1992-03-17 00:00:00 +0000 | [diff] [blame] | 18 | */ |
| 19 | |
| 20 | |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame^] | 21 | /* Short forms of external names for systems with brain-damaged linkers. */ |
| 22 | |
| 23 | #ifdef NEED_SHORT_EXTERNAL_NAMES |
| 24 | #define jpeg_get_small jGetSmall |
| 25 | #define jpeg_free_small jFreeSmall |
| 26 | #define jpeg_get_large jGetLarge |
| 27 | #define jpeg_free_large jFreeLarge |
| 28 | #define jpeg_mem_available jMemAvail |
| 29 | #define jpeg_open_backing_store jOpenBackStore |
| 30 | #define jpeg_mem_init jMemInit |
| 31 | #define jpeg_mem_term jMemTerm |
| 32 | #endif /* NEED_SHORT_EXTERNAL_NAMES */ |
| 33 | |
| 34 | |
Thomas G. Lane | 4a6b730 | 1992-03-17 00:00:00 +0000 | [diff] [blame] | 35 | /* |
| 36 | * These two functions are used to allocate and release small chunks of |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame^] | 37 | * memory. (Typically the total amount requested through jpeg_get_small is |
| 38 | * no more than 20K or so; this will be requested in chunks of a few K each.) |
| 39 | * Behavior should be the same as for the standard library functions malloc |
| 40 | * and free; in particular, jpeg_get_small must return NULL on failure. |
| 41 | * On most systems, these ARE malloc and free. jpeg_free_small is passed the |
| 42 | * size of the object being freed, just in case it's needed. |
Thomas G. Lane | 4a6b730 | 1992-03-17 00:00:00 +0000 | [diff] [blame] | 43 | * On an 80x86 machine using small-data memory model, these manage near heap. |
| 44 | */ |
| 45 | |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame^] | 46 | EXTERN void * jpeg_get_small JPP((j_common_ptr cinfo, size_t sizeofobject)); |
| 47 | EXTERN void jpeg_free_small JPP((j_common_ptr cinfo, void * object, |
| 48 | size_t sizeofobject)); |
Thomas G. Lane | 4a6b730 | 1992-03-17 00:00:00 +0000 | [diff] [blame] | 49 | |
| 50 | /* |
| 51 | * These two functions are used to allocate and release large chunks of |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame^] | 52 | * memory (up to the total free space designated by jpeg_mem_available). |
Thomas G. Lane | 4a6b730 | 1992-03-17 00:00:00 +0000 | [diff] [blame] | 53 | * The interface is the same as above, except that on an 80x86 machine, |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame^] | 54 | * far pointers are used. On most other machines these are identical to |
| 55 | * the jpeg_get/free_small routines; but we keep them separate anyway, |
| 56 | * in case a different allocation strategy is desirable for large chunks. |
Thomas G. Lane | 4a6b730 | 1992-03-17 00:00:00 +0000 | [diff] [blame] | 57 | */ |
| 58 | |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame^] | 59 | EXTERN void FAR * jpeg_get_large JPP((j_common_ptr cinfo,size_t sizeofobject)); |
| 60 | EXTERN void jpeg_free_large JPP((j_common_ptr cinfo, void FAR * object, |
| 61 | size_t sizeofobject)); |
Thomas G. Lane | 4a6b730 | 1992-03-17 00:00:00 +0000 | [diff] [blame] | 62 | |
| 63 | /* |
| 64 | * The macro MAX_ALLOC_CHUNK designates the maximum number of bytes that may |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame^] | 65 | * be requested in a single call to jpeg_get_large (and jpeg_get_small for that |
Thomas G. Lane | 4a6b730 | 1992-03-17 00:00:00 +0000 | [diff] [blame] | 66 | * matter, but that case should never come into play). This macro is needed |
| 67 | * to model the 64Kb-segment-size limit of far addressing on 80x86 machines. |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame^] | 68 | * On those machines, we expect that jconfig.h will provide a proper value. |
| 69 | * On machines with 32-bit flat address spaces, any large constant may be used. |
| 70 | * |
| 71 | * NB: jmemmgr.c expects that MAX_ALLOC_CHUNK will be representable as type |
| 72 | * size_t and will be a multiple of sizeof(align_type). |
Thomas G. Lane | 4a6b730 | 1992-03-17 00:00:00 +0000 | [diff] [blame] | 73 | */ |
| 74 | |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame^] | 75 | #ifndef MAX_ALLOC_CHUNK /* may be overridden in jconfig.h */ |
| 76 | #define MAX_ALLOC_CHUNK 1000000000L |
| 77 | #endif |
Thomas G. Lane | 4a6b730 | 1992-03-17 00:00:00 +0000 | [diff] [blame] | 78 | |
| 79 | /* |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame^] | 80 | * This routine computes the total space still available for allocation by |
| 81 | * jpeg_get_large. If more space than this is needed, backing store will be |
| 82 | * used. NOTE: any memory already allocated must not be counted. |
Thomas G. Lane | 4a6b730 | 1992-03-17 00:00:00 +0000 | [diff] [blame] | 83 | * |
| 84 | * There is a minimum space requirement, corresponding to the minimum |
| 85 | * feasible buffer sizes; jmemmgr.c will request that much space even if |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame^] | 86 | * jpeg_mem_available returns zero. The maximum space needed, enough to hold |
Thomas G. Lane | 4a6b730 | 1992-03-17 00:00:00 +0000 | [diff] [blame] | 87 | * all working storage in memory, is also passed in case it is useful. |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame^] | 88 | * Finally, the total space already allocated is passed. If no better |
| 89 | * method is available, cinfo->mem->max_memory_to_use - already_allocated |
| 90 | * is often a suitable calculation. |
Thomas G. Lane | 4a6b730 | 1992-03-17 00:00:00 +0000 | [diff] [blame] | 91 | * |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame^] | 92 | * It is OK for jpeg_mem_available to underestimate the space available |
| 93 | * (that'll just lead to more backing-store access than is really necessary). |
Thomas G. Lane | 4a6b730 | 1992-03-17 00:00:00 +0000 | [diff] [blame] | 94 | * However, an overestimate will lead to failure. Hence it's wise to subtract |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame^] | 95 | * a slop factor from the true available space. 5% should be enough. |
Thomas G. Lane | 4a6b730 | 1992-03-17 00:00:00 +0000 | [diff] [blame] | 96 | * |
| 97 | * On machines with lots of virtual memory, any large constant may be returned. |
| 98 | * Conversely, zero may be returned to always use the minimum amount of memory. |
| 99 | */ |
| 100 | |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame^] | 101 | EXTERN long jpeg_mem_available JPP((j_common_ptr cinfo, |
| 102 | long min_bytes_needed, |
| 103 | long max_bytes_needed, |
| 104 | long already_allocated)); |
Thomas G. Lane | 4a6b730 | 1992-03-17 00:00:00 +0000 | [diff] [blame] | 105 | |
| 106 | |
| 107 | /* |
| 108 | * This structure holds whatever state is needed to access a single |
| 109 | * backing-store object. The read/write/close method pointers are called |
| 110 | * by jmemmgr.c to manipulate the backing-store object; all other fields |
| 111 | * are private to the system-dependent backing store routines. |
| 112 | */ |
| 113 | |
| 114 | #define TEMP_NAME_LENGTH 64 /* max length of a temporary file's name */ |
| 115 | |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame^] | 116 | #ifdef USE_MSDOS_MEMMGR /* DOS-specific junk */ |
| 117 | |
| 118 | typedef unsigned short XMSH; /* type of extended-memory handles */ |
| 119 | typedef unsigned short EMSH; /* type of expanded-memory handles */ |
| 120 | |
| 121 | typedef union { |
| 122 | short file_handle; /* DOS file handle if it's a temp file */ |
| 123 | XMSH xms_handle; /* handle if it's a chunk of XMS */ |
| 124 | EMSH ems_handle; /* handle if it's a chunk of EMS */ |
| 125 | } handle_union; |
| 126 | |
| 127 | #endif /* USE_MSDOS_MEMMGR */ |
| 128 | |
Thomas G. Lane | 4a6b730 | 1992-03-17 00:00:00 +0000 | [diff] [blame] | 129 | typedef struct backing_store_struct * backing_store_ptr; |
| 130 | |
| 131 | typedef struct backing_store_struct { |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame^] | 132 | /* Methods for reading/writing/closing this backing-store object */ |
| 133 | JMETHOD(void, read_backing_store, (j_common_ptr cinfo, |
| 134 | backing_store_ptr info, |
| 135 | void FAR * buffer_address, |
| 136 | long file_offset, long byte_count)); |
| 137 | JMETHOD(void, write_backing_store, (j_common_ptr cinfo, |
| 138 | backing_store_ptr info, |
| 139 | void FAR * buffer_address, |
| 140 | long file_offset, long byte_count)); |
| 141 | JMETHOD(void, close_backing_store, (j_common_ptr cinfo, |
| 142 | backing_store_ptr info)); |
| 143 | |
| 144 | /* Private fields for system-dependent backing-store management */ |
| 145 | #ifdef USE_MSDOS_MEMMGR |
| 146 | /* For the MS-DOS manager (jmemdos.c), we need: */ |
| 147 | handle_union handle; /* reference to backing-store storage object */ |
| 148 | char temp_name[TEMP_NAME_LENGTH]; /* name if it's a file */ |
| 149 | #else |
| 150 | /* For a typical implementation with temp files, we need: */ |
| 151 | FILE * temp_file; /* stdio reference to temp file */ |
| 152 | char temp_name[TEMP_NAME_LENGTH]; /* name of temp file */ |
| 153 | #endif |
| 154 | } backing_store_info; |
Thomas G. Lane | 4a6b730 | 1992-03-17 00:00:00 +0000 | [diff] [blame] | 155 | |
| 156 | /* |
| 157 | * Initial opening of a backing-store object. This must fill in the |
| 158 | * read/write/close pointers in the object. The read/write routines |
| 159 | * may take an error exit if the specified maximum file size is exceeded. |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame^] | 160 | * (If jpeg_mem_available always returns a large value, this routine can |
| 161 | * just take an error exit.) |
Thomas G. Lane | 4a6b730 | 1992-03-17 00:00:00 +0000 | [diff] [blame] | 162 | */ |
| 163 | |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame^] | 164 | EXTERN void jpeg_open_backing_store JPP((j_common_ptr cinfo, |
| 165 | backing_store_ptr info, |
| 166 | long total_bytes_needed)); |
Thomas G. Lane | 4a6b730 | 1992-03-17 00:00:00 +0000 | [diff] [blame] | 167 | |
| 168 | |
| 169 | /* |
| 170 | * These routines take care of any system-dependent initialization and |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame^] | 171 | * cleanup required. jpeg_mem_init will be called before anything is |
| 172 | * allocated (and, therefore, nothing in cinfo is of use except the error |
| 173 | * manager pointer). It should return a suitable default value for |
| 174 | * max_memory_to_use; this may subsequently be overridden by the surrounding |
| 175 | * application. (Note that max_memory_to_use is only important if |
| 176 | * jpeg_mem_available chooses to consult it ... no one else will.) |
| 177 | * jpeg_mem_term may assume that all requested memory has been freed and that |
| 178 | * all opened backing-store objects have been closed. |
Thomas G. Lane | 4a6b730 | 1992-03-17 00:00:00 +0000 | [diff] [blame] | 179 | */ |
| 180 | |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame^] | 181 | EXTERN long jpeg_mem_init JPP((j_common_ptr cinfo)); |
| 182 | EXTERN void jpeg_mem_term JPP((j_common_ptr cinfo)); |