199 lines
8.0 KiB
C
199 lines
8.0 KiB
C
/*
|
|
* jmemsys.h
|
|
*
|
|
* Copyright (C) 1992-1997, 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. No other
|
|
* modules need include it. (The system-independent portion is jmemmgr.c;
|
|
* there are several different versions of the system-dependent portion.)
|
|
*
|
|
* 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
|
|
* and USE_MAC_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 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 *) 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 jpeg_mem_available).
|
|
* The interface is the same as above, except that on an 80x86 machine,
|
|
* 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.
|
|
*/
|
|
|
|
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 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 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).
|
|
*/
|
|
|
|
#ifndef MAX_ALLOC_CHUNK /* may be overridden in jconfig.h */
|
|
#define MAX_ALLOC_CHUNK 1000000000L
|
|
#endif
|
|
|
|
/*
|
|
* 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
|
|
* 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 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. 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) jpeg_mem_available JPP((j_common_ptr cinfo,
|
|
long min_bytes_needed,
|
|
long max_bytes_needed,
|
|
long already_allocated));
|
|
|
|
|
|
/*
|
|
* This structure holds whatever state is needed to access a single
|
|
* backing-store object. The read/write/close method pointers are called
|
|
* by jmemmgr.c to manipulate the backing-store object; all other fields
|
|
* are private to the system-dependent backing store routines.
|
|
*/
|
|
|
|
#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 */
|
|
|
|
#ifdef USE_MAC_MEMMGR /* Mac-specific junk */
|
|
#include <Files.h>
|
|
#endif /* USE_MAC_MEMMGR */
|
|
|
|
|
|
typedef struct backing_store_struct * backing_store_ptr;
|
|
|
|
typedef struct backing_store_struct {
|
|
/* 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
|
|
#ifdef USE_MAC_MEMMGR
|
|
/* For the Mac manager (jmemmac.c), we need: */
|
|
short temp_file; /* file reference number to temp file */
|
|
FSSpec tempSpec; /* the FSSpec for the temp file */
|
|
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
|
|
#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 jpeg_mem_available always returns a large value, this routine can
|
|
* just take an error exit.)
|
|
*/
|
|
|
|
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. 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(long) jpeg_mem_init JPP((j_common_ptr cinfo));
|
|
EXTERN(void) jpeg_mem_term JPP((j_common_ptr cinfo));
|