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jmemsys.h
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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 
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 
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 
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 
138 
139 typedef struct backing_store_struct {
140  /* Methods for reading/writing/closing this backing-store object */
143  void FAR * buffer_address,
144  long file_offset, long byte_count));
147  void FAR * buffer_address,
148  long file_offset, long byte_count));
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
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 
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));
jpeg_get_small(j_common_ptr cinfo, size_t sizeofobject)
Definition: jmemansi.c:36
JMETHOD(void, read_backing_store,(j_common_ptr cinfo, backing_store_ptr info, void FAR *buffer_address, long file_offset, long byte_count))
namespace GUID const ADDRINFOEXW ADDRINFOEXW struct timeval OVERLAPPED LPLOOKUPSERVICE_COMPLETION_ROUTINE HANDLE * handle
Definition: sock.c:82
struct backing_store_struct * backing_store_ptr
Definition: jmemsys.h:137
char temp_name[TEMP_NAME_LENGTH]
Definition: jmemsys.h:166
jpeg_get_large(j_common_ptr cinfo, size_t sizeofobject)
Definition: jmemansi.c:56
long long max_bytes_needed
Definition: jmemsys.h:104
jpeg_mem_term(j_common_ptr cinfo)
Definition: jmemansi.c:164
EXTERN(void *) jpeg_get_small JPP((j_common_ptr cinfo
size_t sizeofobject
Definition: jmemsys.h:47
write_backing_store(j_common_ptr cinfo, backing_store_ptr info, void FAR *buffer_address, long file_offset, long byte_count)
Definition: jmemansi.c:110
#define FAR
Definition: guiddef.h:36
jpeg_open_backing_store(j_common_ptr cinfo, backing_store_ptr info, long total_bytes_needed)
Definition: jmemansi.c:141
backing_store_ptr long total_bytes_needed
Definition: jmemsys.h:181
struct backing_store_struct backing_store_info
jpeg_free_large(j_common_ptr cinfo, void FAR *object, size_t sizeofobject)
Definition: jmemansi.c:62
long min_bytes_needed
Definition: jmemsys.h:104
#define TEMP_NAME_LENGTH
Definition: jmemsys.h:116
#define JPP(arglist)
Definition: jpeglib.h:877
close_backing_store(j_common_ptr cinfo, backing_store_ptr info)
Definition: jmemansi.c:123
long long long already_allocated
Definition: jmemsys.h:104
jpeg_mem_available(j_common_ptr cinfo, long min_bytes_needed, long max_bytes_needed, long already_allocated)
Definition: jmemansi.c:81
jpeg_mem_init(j_common_ptr cinfo)
Definition: jmemansi.c:158
jpeg_free_small(j_common_ptr cinfo, void *object, size_t sizeofobject)
Definition: jmemansi.c:42
read_backing_store(j_common_ptr cinfo, backing_store_ptr info, void FAR *buffer_address, long file_offset, long byte_count)
Definition: jmemansi.c:97
static FILE * file_handle
Definition: regtests2xml.c:45