2 * CDE - Common Desktop Environment
4 * Copyright (c) 1993-2012, The Open Group. All rights reserved.
6 * These libraries and programs are free software; you can
7 * redistribute them and/or modify them under the terms of the GNU
8 * Lesser General Public License as published by the Free Software
9 * Foundation; either version 2 of the License, or (at your option)
12 * These libraries and programs are distributed in the hope that
13 * they will be useful, but WITHOUT ANY WARRANTY; without even the
14 * implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
15 * PURPOSE. See the GNU Lesser General Public License for more
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with these librararies and programs; if not, write
20 * to the Free Software Foundation, Inc., 51 Franklin Street, Fifth
21 * Floor, Boston, MA 02110-1301 USA
23 /* $XConsortium: jmemsys.h /main/2 1996/05/09 03:52:46 drk $ */
27 * Copyright (C) 1992-1996, Thomas G. Lane.
28 * This file is part of the Independent JPEG Group's software.
29 * For conditions of distribution and use, see the accompanying README file.
31 * This include file defines the interface between the system-independent
32 * and system-dependent portions of the JPEG memory manager. No other
33 * modules need include it. (The system-independent portion is jmemmgr.c;
34 * there are several different versions of the system-dependent portion.)
36 * This file works as-is for the system-dependent memory managers supplied
37 * in the IJG distribution. You may need to modify it if you write a
38 * custom memory manager. If system-dependent changes are needed in
39 * this file, the best method is to #ifdef them based on a configuration
40 * symbol supplied in jconfig.h, as we have done with USE_MSDOS_MEMMGR.
44 /* Short forms of external names for systems with brain-damaged linkers. */
46 #ifdef NEED_SHORT_EXTERNAL_NAMES
47 #define jpeg_get_small jGetSmall
48 #define jpeg_free_small jFreeSmall
49 #define jpeg_get_large jGetLarge
50 #define jpeg_free_large jFreeLarge
51 #define jpeg_mem_available jMemAvail
52 #define jpeg_open_backing_store jOpenBackStore
53 #define jpeg_mem_init jMemInit
54 #define jpeg_mem_term jMemTerm
55 #endif /* NEED_SHORT_EXTERNAL_NAMES */
59 * These two functions are used to allocate and release small chunks of
60 * memory. (Typically the total amount requested through jpeg_get_small is
61 * no more than 20K or so; this will be requested in chunks of a few K each.)
62 * Behavior should be the same as for the standard library functions malloc
63 * and free; in particular, jpeg_get_small must return NULL on failure.
64 * On most systems, these ARE malloc and free. jpeg_free_small is passed the
65 * size of the object being freed, just in case it's needed.
66 * On an 80x86 machine using small-data memory model, these manage near heap.
69 EXTERN(void *) jpeg_get_small JPP((j_common_ptr cinfo, size_t sizeofobject));
70 EXTERN(void) jpeg_free_small JPP((j_common_ptr cinfo, void * object,
71 size_t sizeofobject));
74 * These two functions are used to allocate and release large chunks of
75 * memory (up to the total free space designated by jpeg_mem_available).
76 * The interface is the same as above, except that on an 80x86 machine,
77 * far pointers are used. On most other machines these are identical to
78 * the jpeg_get/free_small routines; but we keep them separate anyway,
79 * in case a different allocation strategy is desirable for large chunks.
82 EXTERN(void FAR *) jpeg_get_large JPP((j_common_ptr cinfo,
83 size_t sizeofobject));
84 EXTERN(void) jpeg_free_large JPP((j_common_ptr cinfo, void FAR * object,
85 size_t sizeofobject));
88 * The macro MAX_ALLOC_CHUNK designates the maximum number of bytes that may
89 * be requested in a single call to jpeg_get_large (and jpeg_get_small for that
90 * matter, but that case should never come into play). This macro is needed
91 * to model the 64Kb-segment-size limit of far addressing on 80x86 machines.
92 * On those machines, we expect that jconfig.h will provide a proper value.
93 * On machines with 32-bit flat address spaces, any large constant may be used.
95 * NB: jmemmgr.c expects that MAX_ALLOC_CHUNK will be representable as type
96 * size_t and will be a multiple of sizeof(align_type).
99 #ifndef MAX_ALLOC_CHUNK /* may be overridden in jconfig.h */
100 #define MAX_ALLOC_CHUNK 1000000000L
104 * This routine computes the total space still available for allocation by
105 * jpeg_get_large. If more space than this is needed, backing store will be
106 * used. NOTE: any memory already allocated must not be counted.
108 * There is a minimum space requirement, corresponding to the minimum
109 * feasible buffer sizes; jmemmgr.c will request that much space even if
110 * jpeg_mem_available returns zero. The maximum space needed, enough to hold
111 * all working storage in memory, is also passed in case it is useful.
112 * Finally, the total space already allocated is passed. If no better
113 * method is available, cinfo->mem->max_memory_to_use - already_allocated
114 * is often a suitable calculation.
116 * It is OK for jpeg_mem_available to underestimate the space available
117 * (that'll just lead to more backing-store access than is really necessary).
118 * However, an overestimate will lead to failure. Hence it's wise to subtract
119 * a slop factor from the true available space. 5% should be enough.
121 * On machines with lots of virtual memory, any large constant may be returned.
122 * Conversely, zero may be returned to always use the minimum amount of memory.
125 EXTERN(long) jpeg_mem_available JPP((j_common_ptr cinfo,
126 long min_bytes_needed,
127 long max_bytes_needed,
128 long already_allocated));
132 * This structure holds whatever state is needed to access a single
133 * backing-store object. The read/write/close method pointers are called
134 * by jmemmgr.c to manipulate the backing-store object; all other fields
135 * are private to the system-dependent backing store routines.
138 #define TEMP_NAME_LENGTH 64 /* max length of a temporary file's name */
140 #ifdef USE_MSDOS_MEMMGR /* DOS-specific junk */
142 typedef unsigned short XMSH; /* type of extended-memory handles */
143 typedef unsigned short EMSH; /* type of expanded-memory handles */
146 short file_handle; /* DOS file handle if it's a temp file */
147 XMSH xms_handle; /* handle if it's a chunk of XMS */
148 EMSH ems_handle; /* handle if it's a chunk of EMS */
151 #endif /* USE_MSDOS_MEMMGR */
153 typedef struct backing_store_struct * backing_store_ptr;
155 typedef struct backing_store_struct {
156 /* Methods for reading/writing/closing this backing-store object */
157 JMETHOD(void, read_backing_store, (j_common_ptr cinfo,
158 backing_store_ptr info,
159 void FAR * buffer_address,
160 long file_offset, long byte_count));
161 JMETHOD(void, write_backing_store, (j_common_ptr cinfo,
162 backing_store_ptr info,
163 void FAR * buffer_address,
164 long file_offset, long byte_count));
165 JMETHOD(void, close_backing_store, (j_common_ptr cinfo,
166 backing_store_ptr info));
168 /* Private fields for system-dependent backing-store management */
169 #ifdef USE_MSDOS_MEMMGR
170 /* For the MS-DOS manager (jmemdos.c), we need: */
171 handle_union handle; /* reference to backing-store storage object */
172 char temp_name[TEMP_NAME_LENGTH]; /* name if it's a file */
174 /* For a typical implementation with temp files, we need: */
175 FILE * temp_file; /* stdio reference to temp file */
176 char temp_name[TEMP_NAME_LENGTH]; /* name of temp file */
178 } backing_store_info;
181 * Initial opening of a backing-store object. This must fill in the
182 * read/write/close pointers in the object. The read/write routines
183 * may take an error exit if the specified maximum file size is exceeded.
184 * (If jpeg_mem_available always returns a large value, this routine can
185 * just take an error exit.)
188 EXTERN(void) jpeg_open_backing_store JPP((j_common_ptr cinfo,
189 backing_store_ptr info,
190 long total_bytes_needed));
194 * These routines take care of any system-dependent initialization and
195 * cleanup required. jpeg_mem_init will be called before anything is
196 * allocated (and, therefore, nothing in cinfo is of use except the error
197 * manager pointer). It should return a suitable default value for
198 * max_memory_to_use; this may subsequently be overridden by the surrounding
199 * application. (Note that max_memory_to_use is only important if
200 * jpeg_mem_available chooses to consult it ... no one else will.)
201 * jpeg_mem_term may assume that all requested memory has been freed and that
202 * all opened backing-store objects have been closed.
205 EXTERN(long) jpeg_mem_init JPP((j_common_ptr cinfo));
206 EXTERN(void) jpeg_mem_term JPP((j_common_ptr cinfo));