/* | |
* 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: */ | |
#ifndef _FPDFAPI_MINI_ | |
FXSYS_FILE * temp_file; /* stdio reference to temp file */ | |
char temp_name[TEMP_NAME_LENGTH]; /* name of temp file */ | |
#endif | |
#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)); |