The Independent JPEG Group's JPEG software v5
diff --git a/jmemsys.h b/jmemsys.h
index 1766a95..033d29a 100644
--- a/jmemsys.h
+++ b/jmemsys.h
@@ -1,78 +1,107 @@
/*
* jmemsys.h
*
- * Copyright (C) 1992, Thomas G. Lane.
+ * Copyright (C) 1992-1994, Thomas G. Lane.
* This file is part of the Independent JPEG Group's software.
* For conditions of distribution and use, see the accompanying README file.
*
* This include file defines the interface between the system-independent
- * and system-dependent portions of the JPEG memory manager. (The system-
- * independent portion is jmemmgr.c; there are several different versions
- * of the system-dependent portion, and of this file for that matter.)
+ * and system-dependent portions of the JPEG memory manager. No other
+ * modules need include it. (The system-independent portion is jmemmgr.c;
+ * there are several different versions of the system-dependent portion.)
*
- * This is a "generic" skeleton that may need to be modified for particular
- * systems. It should be usable as-is on the majority of non-MSDOS machines.
+ * This file works as-is for the system-dependent memory managers supplied
+ * in the IJG distribution. You may need to modify it if you write a
+ * custom memory manager. If system-dependent changes are needed in
+ * this file, the best method is to #ifdef them based on a configuration
+ * symbol supplied in jconfig.h, as we have done with USE_MSDOS_MEMMGR.
*/
+/* Short forms of external names for systems with brain-damaged linkers. */
+
+#ifdef NEED_SHORT_EXTERNAL_NAMES
+#define jpeg_get_small jGetSmall
+#define jpeg_free_small jFreeSmall
+#define jpeg_get_large jGetLarge
+#define jpeg_free_large jFreeLarge
+#define jpeg_mem_available jMemAvail
+#define jpeg_open_backing_store jOpenBackStore
+#define jpeg_mem_init jMemInit
+#define jpeg_mem_term jMemTerm
+#endif /* NEED_SHORT_EXTERNAL_NAMES */
+
+
/*
* These two functions are used to allocate and release small chunks of
- * memory (typically the total amount requested through jget_small is
- * no more than 20Kb or so). Behavior should be the same as for the
- * standard library functions malloc and free; in particular, jget_small
- * returns NULL on failure. On most systems, these ARE malloc and free.
+ * memory. (Typically the total amount requested through jpeg_get_small is
+ * no more than 20K or so; this will be requested in chunks of a few K each.)
+ * Behavior should be the same as for the standard library functions malloc
+ * and free; in particular, jpeg_get_small must return NULL on failure.
+ * On most systems, these ARE malloc and free. jpeg_free_small is passed the
+ * size of the object being freed, just in case it's needed.
* On an 80x86 machine using small-data memory model, these manage near heap.
*/
-EXTERN void * jget_small PP((size_t sizeofobject));
-EXTERN void jfree_small PP((void * object));
+EXTERN void * jpeg_get_small JPP((j_common_ptr cinfo, size_t sizeofobject));
+EXTERN void jpeg_free_small JPP((j_common_ptr cinfo, void * object,
+ size_t sizeofobject));
/*
* These two functions are used to allocate and release large chunks of
- * memory (up to the total free space designated by jmem_available).
+ * memory (up to the total free space designated by jpeg_mem_available).
* The interface is the same as above, except that on an 80x86 machine,
- * far pointers are used. On other systems these ARE the same as above.
+ * far pointers are used. On most other machines these are identical to
+ * the jpeg_get/free_small routines; but we keep them separate anyway,
+ * in case a different allocation strategy is desirable for large chunks.
*/
-#ifdef NEED_FAR_POINTERS /* typically not needed except on 80x86 */
-EXTERN void FAR * jget_large PP((size_t sizeofobject));
-EXTERN void jfree_large PP((void FAR * object));
-#else
-#define jget_large(sizeofobject) jget_small(sizeofobject)
-#define jfree_large(object) jfree_small(object)
-#endif
+EXTERN void FAR * jpeg_get_large JPP((j_common_ptr cinfo,size_t sizeofobject));
+EXTERN void jpeg_free_large JPP((j_common_ptr cinfo, void FAR * object,
+ size_t sizeofobject));
/*
* The macro MAX_ALLOC_CHUNK designates the maximum number of bytes that may
- * be requested in a single call on jget_large (and jget_small for that
+ * be requested in a single call to jpeg_get_large (and jpeg_get_small for that
* matter, but that case should never come into play). This macro is needed
* to model the 64Kb-segment-size limit of far addressing on 80x86 machines.
- * On machines with flat address spaces, any large constant may be used here.
+ * On those machines, we expect that jconfig.h will provide a proper value.
+ * On machines with 32-bit flat address spaces, any large constant may be used.
+ *
+ * NB: jmemmgr.c expects that MAX_ALLOC_CHUNK will be representable as type
+ * size_t and will be a multiple of sizeof(align_type).
*/
-#define MAX_ALLOC_CHUNK 1000000000L
+#ifndef MAX_ALLOC_CHUNK /* may be overridden in jconfig.h */
+#define MAX_ALLOC_CHUNK 1000000000L
+#endif
/*
- * This routine computes the total space available for allocation by
- * jget_large. If more space than this is needed, backing store will be used.
- * NOTE: any memory already allocated must not be counted.
+ * This routine computes the total space still available for allocation by
+ * jpeg_get_large. If more space than this is needed, backing store will be
+ * used. NOTE: any memory already allocated must not be counted.
*
* There is a minimum space requirement, corresponding to the minimum
* feasible buffer sizes; jmemmgr.c will request that much space even if
- * jmem_available returns zero. The maximum space needed, enough to hold
+ * jpeg_mem_available returns zero. The maximum space needed, enough to hold
* all working storage in memory, is also passed in case it is useful.
+ * Finally, the total space already allocated is passed. If no better
+ * method is available, cinfo->mem->max_memory_to_use - already_allocated
+ * is often a suitable calculation.
*
- * It is OK for jmem_available to underestimate the space available (that'll
- * just lead to more backing-store access than is really necessary).
+ * It is OK for jpeg_mem_available to underestimate the space available
+ * (that'll just lead to more backing-store access than is really necessary).
* However, an overestimate will lead to failure. Hence it's wise to subtract
- * a slop factor from the true available space, especially if jget_small space
- * comes from the same pool. 5% should be enough.
+ * a slop factor from the true available space. 5% should be enough.
*
* On machines with lots of virtual memory, any large constant may be returned.
* Conversely, zero may be returned to always use the minimum amount of memory.
*/
-EXTERN long jmem_available PP((long min_bytes_needed, long max_bytes_needed));
+EXTERN long jpeg_mem_available JPP((j_common_ptr cinfo,
+ long min_bytes_needed,
+ long max_bytes_needed,
+ long already_allocated));
/*
@@ -84,44 +113,70 @@
#define TEMP_NAME_LENGTH 64 /* max length of a temporary file's name */
+#ifdef USE_MSDOS_MEMMGR /* DOS-specific junk */
+
+typedef unsigned short XMSH; /* type of extended-memory handles */
+typedef unsigned short EMSH; /* type of expanded-memory handles */
+
+typedef union {
+ short file_handle; /* DOS file handle if it's a temp file */
+ XMSH xms_handle; /* handle if it's a chunk of XMS */
+ EMSH ems_handle; /* handle if it's a chunk of EMS */
+} handle_union;
+
+#endif /* USE_MSDOS_MEMMGR */
+
typedef struct backing_store_struct * backing_store_ptr;
typedef struct backing_store_struct {
- /* Methods for reading/writing/closing this backing-store object */
- METHOD(void, read_backing_store, (backing_store_ptr info,
- void FAR * buffer_address,
- long file_offset, long byte_count));
- METHOD(void, write_backing_store, (backing_store_ptr info,
- void FAR * buffer_address,
- long file_offset, long byte_count));
- METHOD(void, close_backing_store, (backing_store_ptr info));
- /* Private fields for system-dependent backing-store management */
- /* For a typical implementation with temp files, we might need: */
- FILE * temp_file; /* stdio reference to temp file */
- char temp_name[TEMP_NAME_LENGTH]; /* name of temp file */
- } backing_store_info;
+ /* Methods for reading/writing/closing this backing-store object */
+ JMETHOD(void, read_backing_store, (j_common_ptr cinfo,
+ backing_store_ptr info,
+ void FAR * buffer_address,
+ long file_offset, long byte_count));
+ JMETHOD(void, write_backing_store, (j_common_ptr cinfo,
+ backing_store_ptr info,
+ void FAR * buffer_address,
+ long file_offset, long byte_count));
+ JMETHOD(void, close_backing_store, (j_common_ptr cinfo,
+ backing_store_ptr info));
+
+ /* Private fields for system-dependent backing-store management */
+#ifdef USE_MSDOS_MEMMGR
+ /* For the MS-DOS manager (jmemdos.c), we need: */
+ handle_union handle; /* reference to backing-store storage object */
+ char temp_name[TEMP_NAME_LENGTH]; /* name if it's a file */
+#else
+ /* For a typical implementation with temp files, we need: */
+ FILE * temp_file; /* stdio reference to temp file */
+ char temp_name[TEMP_NAME_LENGTH]; /* name of temp file */
+#endif
+} backing_store_info;
/*
* Initial opening of a backing-store object. This must fill in the
* read/write/close pointers in the object. The read/write routines
* may take an error exit if the specified maximum file size is exceeded.
- * (If jmem_available always returns a large value, this routine can just
- * take an error exit.)
+ * (If jpeg_mem_available always returns a large value, this routine can
+ * just take an error exit.)
*/
-EXTERN void jopen_backing_store PP((backing_store_ptr info,
- long total_bytes_needed));
+EXTERN void jpeg_open_backing_store JPP((j_common_ptr cinfo,
+ backing_store_ptr info,
+ long total_bytes_needed));
/*
* These routines take care of any system-dependent initialization and
- * cleanup required. The system methods struct address should be saved
- * by jmem_init in case an error exit must be taken. jmem_term may assume
- * that all requested memory has been freed and that all opened backing-
- * store objects have been closed.
- * NB: jmem_term may be called more than once, and must behave reasonably
- * if that happens.
+ * cleanup required. jpeg_mem_init will be called before anything is
+ * allocated (and, therefore, nothing in cinfo is of use except the error
+ * manager pointer). It should return a suitable default value for
+ * max_memory_to_use; this may subsequently be overridden by the surrounding
+ * application. (Note that max_memory_to_use is only important if
+ * jpeg_mem_available chooses to consult it ... no one else will.)
+ * jpeg_mem_term may assume that all requested memory has been freed and that
+ * all opened backing-store objects have been closed.
*/
-EXTERN void jmem_init PP((external_methods_ptr emethods));
-EXTERN void jmem_term PP((void));
+EXTERN long jpeg_mem_init JPP((j_common_ptr cinfo));
+EXTERN void jpeg_mem_term JPP((j_common_ptr cinfo));