nuclear@2: /*
nuclear@2:  * jmemsys.h
nuclear@2:  *
nuclear@2:  * Copyright (C) 1992-1997, Thomas G. Lane.
nuclear@2:  * This file is part of the Independent JPEG Group's software.
nuclear@2:  * For conditions of distribution and use, see the accompanying README file.
nuclear@2:  *
nuclear@2:  * This include file defines the interface between the system-independent
nuclear@2:  * and system-dependent portions of the JPEG memory manager.  No other
nuclear@2:  * modules need include it.  (The system-independent portion is jmemmgr.c;
nuclear@2:  * there are several different versions of the system-dependent portion.)
nuclear@2:  *
nuclear@2:  * This file works as-is for the system-dependent memory managers supplied
nuclear@2:  * in the IJG distribution.  You may need to modify it if you write a
nuclear@2:  * custom memory manager.  If system-dependent changes are needed in
nuclear@2:  * this file, the best method is to #ifdef them based on a configuration
nuclear@2:  * symbol supplied in jconfig.h, as we have done with USE_MSDOS_MEMMGR
nuclear@2:  * and USE_MAC_MEMMGR.
nuclear@2:  */
nuclear@2: 
nuclear@2: 
nuclear@2: /* Short forms of external names for systems with brain-damaged linkers. */
nuclear@2: 
nuclear@2: #ifdef NEED_SHORT_EXTERNAL_NAMES
nuclear@2: #define jpeg_get_small		jGetSmall
nuclear@2: #define jpeg_free_small		jFreeSmall
nuclear@2: #define jpeg_get_large		jGetLarge
nuclear@2: #define jpeg_free_large		jFreeLarge
nuclear@2: #define jpeg_mem_available	jMemAvail
nuclear@2: #define jpeg_open_backing_store	jOpenBackStore
nuclear@2: #define jpeg_mem_init		jMemInit
nuclear@2: #define jpeg_mem_term		jMemTerm
nuclear@2: #endif /* NEED_SHORT_EXTERNAL_NAMES */
nuclear@2: 
nuclear@2: 
nuclear@2: /*
nuclear@2:  * These two functions are used to allocate and release small chunks of
nuclear@2:  * memory.  (Typically the total amount requested through jpeg_get_small is
nuclear@2:  * no more than 20K or so; this will be requested in chunks of a few K each.)
nuclear@2:  * Behavior should be the same as for the standard library functions malloc
nuclear@2:  * and free; in particular, jpeg_get_small must return NULL on failure.
nuclear@2:  * On most systems, these ARE malloc and free.  jpeg_free_small is passed the
nuclear@2:  * size of the object being freed, just in case it's needed.
nuclear@2:  * On an 80x86 machine using small-data memory model, these manage near heap.
nuclear@2:  */
nuclear@2: 
nuclear@2: EXTERN(void *) jpeg_get_small JPP((j_common_ptr cinfo, size_t sizeofobject));
nuclear@2: EXTERN(void) jpeg_free_small JPP((j_common_ptr cinfo, void * object,
nuclear@2: 				  size_t sizeofobject));
nuclear@2: 
nuclear@2: /*
nuclear@2:  * These two functions are used to allocate and release large chunks of
nuclear@2:  * memory (up to the total free space designated by jpeg_mem_available).
nuclear@2:  * The interface is the same as above, except that on an 80x86 machine,
nuclear@2:  * far pointers are used.  On most other machines these are identical to
nuclear@2:  * the jpeg_get/free_small routines; but we keep them separate anyway,
nuclear@2:  * in case a different allocation strategy is desirable for large chunks.
nuclear@2:  */
nuclear@2: 
nuclear@2: EXTERN(void FAR *) jpeg_get_large JPP((j_common_ptr cinfo,
nuclear@2: 				       size_t sizeofobject));
nuclear@2: EXTERN(void) jpeg_free_large JPP((j_common_ptr cinfo, void FAR * object,
nuclear@2: 				  size_t sizeofobject));
nuclear@2: 
nuclear@2: /*
nuclear@2:  * The macro MAX_ALLOC_CHUNK designates the maximum number of bytes that may
nuclear@2:  * be requested in a single call to jpeg_get_large (and jpeg_get_small for that
nuclear@2:  * matter, but that case should never come into play).  This macro is needed
nuclear@2:  * to model the 64Kb-segment-size limit of far addressing on 80x86 machines.
nuclear@2:  * On those machines, we expect that jconfig.h will provide a proper value.
nuclear@2:  * On machines with 32-bit flat address spaces, any large constant may be used.
nuclear@2:  *
nuclear@2:  * NB: jmemmgr.c expects that MAX_ALLOC_CHUNK will be representable as type
nuclear@2:  * size_t and will be a multiple of sizeof(align_type).
nuclear@2:  */
nuclear@2: 
nuclear@2: #ifndef MAX_ALLOC_CHUNK		/* may be overridden in jconfig.h */
nuclear@2: #define MAX_ALLOC_CHUNK  1000000000L
nuclear@2: #endif
nuclear@2: 
nuclear@2: /*
nuclear@2:  * This routine computes the total space still available for allocation by
nuclear@2:  * jpeg_get_large.  If more space than this is needed, backing store will be
nuclear@2:  * used.  NOTE: any memory already allocated must not be counted.
nuclear@2:  *
nuclear@2:  * There is a minimum space requirement, corresponding to the minimum
nuclear@2:  * feasible buffer sizes; jmemmgr.c will request that much space even if
nuclear@2:  * jpeg_mem_available returns zero.  The maximum space needed, enough to hold
nuclear@2:  * all working storage in memory, is also passed in case it is useful.
nuclear@2:  * Finally, the total space already allocated is passed.  If no better
nuclear@2:  * method is available, cinfo->mem->max_memory_to_use - already_allocated
nuclear@2:  * is often a suitable calculation.
nuclear@2:  *
nuclear@2:  * It is OK for jpeg_mem_available to underestimate the space available
nuclear@2:  * (that'll just lead to more backing-store access than is really necessary).
nuclear@2:  * However, an overestimate will lead to failure.  Hence it's wise to subtract
nuclear@2:  * a slop factor from the true available space.  5% should be enough.
nuclear@2:  *
nuclear@2:  * On machines with lots of virtual memory, any large constant may be returned.
nuclear@2:  * Conversely, zero may be returned to always use the minimum amount of memory.
nuclear@2:  */
nuclear@2: 
nuclear@2: EXTERN(long) jpeg_mem_available JPP((j_common_ptr cinfo,
nuclear@2: 				     long min_bytes_needed,
nuclear@2: 				     long max_bytes_needed,
nuclear@2: 				     long already_allocated));
nuclear@2: 
nuclear@2: 
nuclear@2: /*
nuclear@2:  * This structure holds whatever state is needed to access a single
nuclear@2:  * backing-store object.  The read/write/close method pointers are called
nuclear@2:  * by jmemmgr.c to manipulate the backing-store object; all other fields
nuclear@2:  * are private to the system-dependent backing store routines.
nuclear@2:  */
nuclear@2: 
nuclear@2: #define TEMP_NAME_LENGTH   64	/* max length of a temporary file's name */
nuclear@2: 
nuclear@2: 
nuclear@2: #ifdef USE_MSDOS_MEMMGR		/* DOS-specific junk */
nuclear@2: 
nuclear@2: typedef unsigned short XMSH;	/* type of extended-memory handles */
nuclear@2: typedef unsigned short EMSH;	/* type of expanded-memory handles */
nuclear@2: 
nuclear@2: typedef union {
nuclear@2:   short file_handle;		/* DOS file handle if it's a temp file */
nuclear@2:   XMSH xms_handle;		/* handle if it's a chunk of XMS */
nuclear@2:   EMSH ems_handle;		/* handle if it's a chunk of EMS */
nuclear@2: } handle_union;
nuclear@2: 
nuclear@2: #endif /* USE_MSDOS_MEMMGR */
nuclear@2: 
nuclear@2: #ifdef USE_MAC_MEMMGR		/* Mac-specific junk */
nuclear@2: #include <Files.h>
nuclear@2: #endif /* USE_MAC_MEMMGR */
nuclear@2: 
nuclear@2: 
nuclear@2: typedef struct backing_store_struct * backing_store_ptr;
nuclear@2: 
nuclear@2: typedef struct backing_store_struct {
nuclear@2:   /* Methods for reading/writing/closing this backing-store object */
nuclear@2:   JMETHOD(void, read_backing_store, (j_common_ptr cinfo,
nuclear@2: 				     backing_store_ptr info,
nuclear@2: 				     void FAR * buffer_address,
nuclear@2: 				     long file_offset, long byte_count));
nuclear@2:   JMETHOD(void, write_backing_store, (j_common_ptr cinfo,
nuclear@2: 				      backing_store_ptr info,
nuclear@2: 				      void FAR * buffer_address,
nuclear@2: 				      long file_offset, long byte_count));
nuclear@2:   JMETHOD(void, close_backing_store, (j_common_ptr cinfo,
nuclear@2: 				      backing_store_ptr info));
nuclear@2: 
nuclear@2:   /* Private fields for system-dependent backing-store management */
nuclear@2: #ifdef USE_MSDOS_MEMMGR
nuclear@2:   /* For the MS-DOS manager (jmemdos.c), we need: */
nuclear@2:   handle_union handle;		/* reference to backing-store storage object */
nuclear@2:   char temp_name[TEMP_NAME_LENGTH]; /* name if it's a file */
nuclear@2: #else
nuclear@2: #ifdef USE_MAC_MEMMGR
nuclear@2:   /* For the Mac manager (jmemmac.c), we need: */
nuclear@2:   short temp_file;		/* file reference number to temp file */
nuclear@2:   FSSpec tempSpec;		/* the FSSpec for the temp file */
nuclear@2:   char temp_name[TEMP_NAME_LENGTH]; /* name if it's a file */
nuclear@2: #else
nuclear@2:   /* For a typical implementation with temp files, we need: */
nuclear@2:   FILE * temp_file;		/* stdio reference to temp file */
nuclear@2:   char temp_name[TEMP_NAME_LENGTH]; /* name of temp file */
nuclear@2: #endif
nuclear@2: #endif
nuclear@2: } backing_store_info;
nuclear@2: 
nuclear@2: 
nuclear@2: /*
nuclear@2:  * Initial opening of a backing-store object.  This must fill in the
nuclear@2:  * read/write/close pointers in the object.  The read/write routines
nuclear@2:  * may take an error exit if the specified maximum file size is exceeded.
nuclear@2:  * (If jpeg_mem_available always returns a large value, this routine can
nuclear@2:  * just take an error exit.)
nuclear@2:  */
nuclear@2: 
nuclear@2: EXTERN(void) jpeg_open_backing_store JPP((j_common_ptr cinfo,
nuclear@2: 					  backing_store_ptr info,
nuclear@2: 					  long total_bytes_needed));
nuclear@2: 
nuclear@2: 
nuclear@2: /*
nuclear@2:  * These routines take care of any system-dependent initialization and
nuclear@2:  * cleanup required.  jpeg_mem_init will be called before anything is
nuclear@2:  * allocated (and, therefore, nothing in cinfo is of use except the error
nuclear@2:  * manager pointer).  It should return a suitable default value for
nuclear@2:  * max_memory_to_use; this may subsequently be overridden by the surrounding
nuclear@2:  * application.  (Note that max_memory_to_use is only important if
nuclear@2:  * jpeg_mem_available chooses to consult it ... no one else will.)
nuclear@2:  * jpeg_mem_term may assume that all requested memory has been freed and that
nuclear@2:  * all opened backing-store objects have been closed.
nuclear@2:  */
nuclear@2: 
nuclear@2: EXTERN(long) jpeg_mem_init JPP((j_common_ptr cinfo));
nuclear@2: EXTERN(void) jpeg_mem_term JPP((j_common_ptr cinfo));