nuclear@1: /* nuclear@1: * jmemsys.h nuclear@1: * nuclear@1: * Copyright (C) 1992-1997, Thomas G. Lane. nuclear@1: * This file is part of the Independent JPEG Group's software. nuclear@1: * For conditions of distribution and use, see the accompanying README file. nuclear@1: * nuclear@1: * This include file defines the interface between the system-independent nuclear@1: * and system-dependent portions of the JPEG memory manager. No other nuclear@1: * modules need include it. (The system-independent portion is jmemmgr.c; nuclear@1: * there are several different versions of the system-dependent portion.) nuclear@1: * nuclear@1: * This file works as-is for the system-dependent memory managers supplied nuclear@1: * in the IJG distribution. You may need to modify it if you write a nuclear@1: * custom memory manager. If system-dependent changes are needed in nuclear@1: * this file, the best method is to #ifdef them based on a configuration nuclear@1: * symbol supplied in jconfig.h, as we have done with USE_MSDOS_MEMMGR nuclear@1: * and USE_MAC_MEMMGR. nuclear@1: */ nuclear@1: nuclear@1: nuclear@1: /* Short forms of external names for systems with brain-damaged linkers. */ nuclear@1: nuclear@1: #ifdef NEED_SHORT_EXTERNAL_NAMES nuclear@1: #define jpeg_get_small jGetSmall nuclear@1: #define jpeg_free_small jFreeSmall nuclear@1: #define jpeg_get_large jGetLarge nuclear@1: #define jpeg_free_large jFreeLarge nuclear@1: #define jpeg_mem_available jMemAvail nuclear@1: #define jpeg_open_backing_store jOpenBackStore nuclear@1: #define jpeg_mem_init jMemInit nuclear@1: #define jpeg_mem_term jMemTerm nuclear@1: #endif /* NEED_SHORT_EXTERNAL_NAMES */ nuclear@1: nuclear@1: nuclear@1: /* nuclear@1: * These two functions are used to allocate and release small chunks of nuclear@1: * memory. (Typically the total amount requested through jpeg_get_small is nuclear@1: * no more than 20K or so; this will be requested in chunks of a few K each.) nuclear@1: * Behavior should be the same as for the standard library functions malloc nuclear@1: * and free; in particular, jpeg_get_small must return NULL on failure. nuclear@1: * On most systems, these ARE malloc and free. jpeg_free_small is passed the nuclear@1: * size of the object being freed, just in case it's needed. nuclear@1: * On an 80x86 machine using small-data memory model, these manage near heap. nuclear@1: */ nuclear@1: nuclear@1: EXTERN(void *) jpeg_get_small JPP((j_common_ptr cinfo, size_t sizeofobject)); nuclear@1: EXTERN(void) jpeg_free_small JPP((j_common_ptr cinfo, void * object, nuclear@1: size_t sizeofobject)); nuclear@1: nuclear@1: /* nuclear@1: * These two functions are used to allocate and release large chunks of nuclear@1: * memory (up to the total free space designated by jpeg_mem_available). nuclear@1: * The interface is the same as above, except that on an 80x86 machine, nuclear@1: * far pointers are used. On most other machines these are identical to nuclear@1: * the jpeg_get/free_small routines; but we keep them separate anyway, nuclear@1: * in case a different allocation strategy is desirable for large chunks. nuclear@1: */ nuclear@1: nuclear@1: EXTERN(void FAR *) jpeg_get_large JPP((j_common_ptr cinfo, nuclear@1: size_t sizeofobject)); nuclear@1: EXTERN(void) jpeg_free_large JPP((j_common_ptr cinfo, void FAR * object, nuclear@1: size_t sizeofobject)); nuclear@1: nuclear@1: /* nuclear@1: * The macro MAX_ALLOC_CHUNK designates the maximum number of bytes that may nuclear@1: * be requested in a single call to jpeg_get_large (and jpeg_get_small for that nuclear@1: * matter, but that case should never come into play). This macro is needed nuclear@1: * to model the 64Kb-segment-size limit of far addressing on 80x86 machines. nuclear@1: * On those machines, we expect that jconfig.h will provide a proper value. nuclear@1: * On machines with 32-bit flat address spaces, any large constant may be used. nuclear@1: * nuclear@1: * NB: jmemmgr.c expects that MAX_ALLOC_CHUNK will be representable as type nuclear@1: * size_t and will be a multiple of sizeof(align_type). nuclear@1: */ nuclear@1: nuclear@1: #ifndef MAX_ALLOC_CHUNK /* may be overridden in jconfig.h */ nuclear@1: #define MAX_ALLOC_CHUNK 1000000000L nuclear@1: #endif nuclear@1: nuclear@1: /* nuclear@1: * This routine computes the total space still available for allocation by nuclear@1: * jpeg_get_large. If more space than this is needed, backing store will be nuclear@1: * used. NOTE: any memory already allocated must not be counted. nuclear@1: * nuclear@1: * There is a minimum space requirement, corresponding to the minimum nuclear@1: * feasible buffer sizes; jmemmgr.c will request that much space even if nuclear@1: * jpeg_mem_available returns zero. The maximum space needed, enough to hold nuclear@1: * all working storage in memory, is also passed in case it is useful. nuclear@1: * Finally, the total space already allocated is passed. If no better nuclear@1: * method is available, cinfo->mem->max_memory_to_use - already_allocated nuclear@1: * is often a suitable calculation. nuclear@1: * nuclear@1: * It is OK for jpeg_mem_available to underestimate the space available nuclear@1: * (that'll just lead to more backing-store access than is really necessary). nuclear@1: * However, an overestimate will lead to failure. Hence it's wise to subtract nuclear@1: * a slop factor from the true available space. 5% should be enough. nuclear@1: * nuclear@1: * On machines with lots of virtual memory, any large constant may be returned. nuclear@1: * Conversely, zero may be returned to always use the minimum amount of memory. nuclear@1: */ nuclear@1: nuclear@1: EXTERN(long) jpeg_mem_available JPP((j_common_ptr cinfo, nuclear@1: long min_bytes_needed, nuclear@1: long max_bytes_needed, nuclear@1: long already_allocated)); nuclear@1: nuclear@1: nuclear@1: /* nuclear@1: * This structure holds whatever state is needed to access a single nuclear@1: * backing-store object. The read/write/close method pointers are called nuclear@1: * by jmemmgr.c to manipulate the backing-store object; all other fields nuclear@1: * are private to the system-dependent backing store routines. nuclear@1: */ nuclear@1: nuclear@1: #define TEMP_NAME_LENGTH 64 /* max length of a temporary file's name */ nuclear@1: nuclear@1: nuclear@1: #ifdef USE_MSDOS_MEMMGR /* DOS-specific junk */ nuclear@1: nuclear@1: typedef unsigned short XMSH; /* type of extended-memory handles */ nuclear@1: typedef unsigned short EMSH; /* type of expanded-memory handles */ nuclear@1: nuclear@1: typedef union { nuclear@1: short file_handle; /* DOS file handle if it's a temp file */ nuclear@1: XMSH xms_handle; /* handle if it's a chunk of XMS */ nuclear@1: EMSH ems_handle; /* handle if it's a chunk of EMS */ nuclear@1: } handle_union; nuclear@1: nuclear@1: #endif /* USE_MSDOS_MEMMGR */ nuclear@1: nuclear@1: #ifdef USE_MAC_MEMMGR /* Mac-specific junk */ nuclear@1: #include nuclear@1: #endif /* USE_MAC_MEMMGR */ nuclear@1: nuclear@1: nuclear@1: typedef struct backing_store_struct * backing_store_ptr; nuclear@1: nuclear@1: typedef struct backing_store_struct { nuclear@1: /* Methods for reading/writing/closing this backing-store object */ nuclear@1: JMETHOD(void, read_backing_store, (j_common_ptr cinfo, nuclear@1: backing_store_ptr info, nuclear@1: void FAR * buffer_address, nuclear@1: long file_offset, long byte_count)); nuclear@1: JMETHOD(void, write_backing_store, (j_common_ptr cinfo, nuclear@1: backing_store_ptr info, nuclear@1: void FAR * buffer_address, nuclear@1: long file_offset, long byte_count)); nuclear@1: JMETHOD(void, close_backing_store, (j_common_ptr cinfo, nuclear@1: backing_store_ptr info)); nuclear@1: nuclear@1: /* Private fields for system-dependent backing-store management */ nuclear@1: #ifdef USE_MSDOS_MEMMGR nuclear@1: /* For the MS-DOS manager (jmemdos.c), we need: */ nuclear@1: handle_union handle; /* reference to backing-store storage object */ nuclear@1: char temp_name[TEMP_NAME_LENGTH]; /* name if it's a file */ nuclear@1: #else nuclear@1: #ifdef USE_MAC_MEMMGR nuclear@1: /* For the Mac manager (jmemmac.c), we need: */ nuclear@1: short temp_file; /* file reference number to temp file */ nuclear@1: FSSpec tempSpec; /* the FSSpec for the temp file */ nuclear@1: char temp_name[TEMP_NAME_LENGTH]; /* name if it's a file */ nuclear@1: #else nuclear@1: /* For a typical implementation with temp files, we need: */ nuclear@1: FILE * temp_file; /* stdio reference to temp file */ nuclear@1: char temp_name[TEMP_NAME_LENGTH]; /* name of temp file */ nuclear@1: #endif nuclear@1: #endif nuclear@1: } backing_store_info; nuclear@1: nuclear@1: nuclear@1: /* nuclear@1: * Initial opening of a backing-store object. This must fill in the nuclear@1: * read/write/close pointers in the object. The read/write routines nuclear@1: * may take an error exit if the specified maximum file size is exceeded. nuclear@1: * (If jpeg_mem_available always returns a large value, this routine can nuclear@1: * just take an error exit.) nuclear@1: */ nuclear@1: nuclear@1: EXTERN(void) jpeg_open_backing_store JPP((j_common_ptr cinfo, nuclear@1: backing_store_ptr info, nuclear@1: long total_bytes_needed)); nuclear@1: nuclear@1: nuclear@1: /* nuclear@1: * These routines take care of any system-dependent initialization and nuclear@1: * cleanup required. jpeg_mem_init will be called before anything is nuclear@1: * allocated (and, therefore, nothing in cinfo is of use except the error nuclear@1: * manager pointer). It should return a suitable default value for nuclear@1: * max_memory_to_use; this may subsequently be overridden by the surrounding nuclear@1: * application. (Note that max_memory_to_use is only important if nuclear@1: * jpeg_mem_available chooses to consult it ... no one else will.) nuclear@1: * jpeg_mem_term may assume that all requested memory has been freed and that nuclear@1: * all opened backing-store objects have been closed. nuclear@1: */ nuclear@1: nuclear@1: EXTERN(long) jpeg_mem_init JPP((j_common_ptr cinfo)); nuclear@1: EXTERN(void) jpeg_mem_term JPP((j_common_ptr cinfo));