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639 lines
20 KiB
C++
639 lines
20 KiB
C++
/*
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* jmemdos.c
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*
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* Copyright (C) 1992-1994, Thomas G. Lane.
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* This file is part of the Independent JPEG Group's software.
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* For conditions of distribution and use, see the accompanying README file.
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*
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* This file provides an MS-DOS-compatible implementation of the system-
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* dependent portion of the JPEG memory manager. Temporary data can be
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* stored in extended or expanded memory as well as in regular DOS files.
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*
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* If you use this file, you must be sure that NEED_FAR_POINTERS is defined
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* if you compile in a small-data memory model; it should NOT be defined if
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* you use a large-data memory model. This file is not recommended if you
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* are using a flat-memory-space 386 environment such as DJGCC or Watcom C.
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* Also, this code will NOT work if struct fields are aligned on greater than
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* 2-byte boundaries.
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*
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* Based on code contributed by Ge' Weijers.
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*/
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/*
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* If you have both extended and expanded memory, you may want to change the
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* order in which they are tried in jopen_backing_store. On a 286 machine
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* expanded memory is usually faster, since extended memory access involves
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* an expensive protected-mode-and-back switch. On 386 and better, extended
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* memory is usually faster. As distributed, the code tries extended memory
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* first (what? not everyone has a 386? :-).
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*
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* You can disable use of extended/expanded memory entirely by altering these
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* definitions or overriding them from the Makefile (eg, -DEMS_SUPPORTED=0).
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*/
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#ifndef XMS_SUPPORTED
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#define XMS_SUPPORTED 1
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#endif
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#ifndef EMS_SUPPORTED
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#define EMS_SUPPORTED 1
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#endif
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#define JPEG_INTERNALS
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#include "jinclude.h"
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#include "jpeglib.h"
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#include "jmemsys.h" /* import the system-dependent declarations */
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#ifndef HAVE_STDLIB_H /* <stdlib.h> should declare these */
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extern void * malloc JPP( (size_t size) );
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extern void free JPP( (void * ptr) );
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extern char * getenv JPP( (const char * name) );
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#endif
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#ifdef NEED_FAR_POINTERS
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#ifdef __TURBOC__
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/* These definitions work for Borland C (Turbo C) */
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#include <alloc.h> /* need farmalloc(), farfree() */
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#define far_malloc( x ) farmalloc( x )
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#define far_free( x ) farfree( x )
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#else
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/* These definitions work for Microsoft C and compatible compilers */
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#include <malloc.h> /* need _fmalloc(), _ffree() */
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#define far_malloc( x ) _fmalloc( x )
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#define far_free( x ) _ffree( x )
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#endif
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#else /* not NEED_FAR_POINTERS */
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#define far_malloc( x ) malloc( x )
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#define far_free( x ) free( x )
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#endif /* NEED_FAR_POINTERS */
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#ifdef DONT_USE_B_MODE /* define mode parameters for fopen() */
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#define READ_BINARY "r"
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#else
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#define READ_BINARY "rb"
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#endif
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#if MAX_ALLOC_CHUNK >= 65535L /* make sure jconfig.h got this right */
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MAX_ALLOC_CHUNK should be less than 64 K. /* deliberate syntax error */
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#endif
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/*
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* Declarations for assembly-language support routines (see jmemdosa.asm).
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*
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* The functions are declared "far" as are all pointer arguments;
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* this ensures the assembly source code will work regardless of the
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* compiler memory model. We assume "short" is 16 bits, "long" is 32.
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*/
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typedef void far * XMSDRIVER; /* actually a pointer to code */
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typedef struct { /* registers for calling XMS driver */
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unsigned short ax, dx, bx;
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void far * ds_si;
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} XMScontext;
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typedef struct { /* registers for calling EMS driver */
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unsigned short ax, dx, bx;
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void far * ds_si;
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} EMScontext;
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EXTERN short far jdos_open JPP( ( short far * handle, char far * filename ) );
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EXTERN short far jdos_close JPP( (short handle) );
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EXTERN short far jdos_seek JPP( ( short handle, long offset ) );
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EXTERN short far jdos_read JPP( ( short handle, void far * buffer,
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unsigned short count ) );
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EXTERN short far jdos_write JPP( ( short handle, void far * buffer,
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unsigned short count ) );
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EXTERN void far jxms_getdriver JPP( (XMSDRIVER far *) );
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EXTERN void far jxms_calldriver JPP( ( XMSDRIVER, XMScontext far * ) );
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EXTERN short far jems_available JPP( (void) );
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EXTERN void far jems_calldriver JPP( (EMScontext far *) );
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/*
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* Selection of a file name for a temporary file.
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* This is highly system-dependent, and you may want to customize it.
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*/
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static int next_file_num; /* to distinguish among several temp files */
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LOCAL void
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select_file_name( char * fname ) {
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const char * env;
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char * ptr;
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FILE * tfile;
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/* Keep generating file names till we find one that's not in use */
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for (;; ) {
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/* Get temp directory name from environment TMP or TEMP variable;
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* if none, use "."
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*/
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if ( ( env = (const char *) getenv( "TMP" ) ) == NULL ) {
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if ( ( env = (const char *) getenv( "TEMP" ) ) == NULL ) {
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env = ".";
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}
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}
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if ( *env == '\0' ) {/* null string means "." */
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env = ".";
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}
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ptr = fname; /* copy name to fname */
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while ( *env != '\0' ) {
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*ptr++ = *env++;
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}
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if ( ( ptr[-1] != '\\' ) && ( ptr[-1] != '/' ) ) {
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*ptr++ = '\\';
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} /* append backslash if not in env variable */
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/* Append a suitable file name */
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next_file_num++; /* advance counter */
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sprintf( ptr, "JPG%03d.TMP", next_file_num );
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/* Probe to see if file name is already in use */
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if ( ( tfile = fopen( fname, READ_BINARY ) ) == NULL ) {
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break;
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}
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fclose( tfile );/* oops, it's there; close tfile & try again */
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}
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}
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/*
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* Near-memory allocation and freeing are controlled by the regular library
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* routines malloc() and free().
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*/
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GLOBAL void *
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jpeg_get_small( j_common_ptr cinfo, size_t sizeofobject ) {
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return (void *) malloc( sizeofobject );
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}
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GLOBAL void
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jpeg_free_small( j_common_ptr cinfo, void * object, size_t sizeofobject ) {
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free( object );
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}
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/*
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* "Large" objects are allocated in far memory, if possible
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*/
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GLOBAL void FAR *
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jpeg_get_large( j_common_ptr cinfo, size_t sizeofobject ) {
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return (void FAR *) far_malloc( sizeofobject );
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}
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GLOBAL void
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jpeg_free_large( j_common_ptr cinfo, void FAR * object, size_t sizeofobject ) {
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far_free( object );
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}
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/*
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* This routine computes the total memory space available for allocation.
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* It's impossible to do this in a portable way; our current solution is
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* to make the user tell us (with a default value set at compile time).
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* If you can actually get the available space, it's a good idea to subtract
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* a slop factor of 5% or so.
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*/
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#ifndef DEFAULT_MAX_MEM /* so can override from makefile */
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#define DEFAULT_MAX_MEM 300000L /* for total usage about 450K */
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#endif
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GLOBAL long
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jpeg_mem_available( j_common_ptr cinfo, long min_bytes_needed,
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long max_bytes_needed, long already_allocated ) {
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return cinfo->mem->max_memory_to_use - already_allocated;
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}
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/*
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* Backing store (temporary file) management.
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* Backing store objects are only used when the value returned by
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* jpeg_mem_available is less than the total space needed. You can dispense
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* with these routines if you have plenty of virtual memory; see jmemnobs.c.
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*/
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/*
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* For MS-DOS we support three types of backing storage:
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* 1. Conventional DOS files. We access these by direct DOS calls rather
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* than via the stdio package. This provides a bit better performance,
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* but the real reason is that the buffers to be read or written are FAR.
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* The stdio library for small-data memory models can't cope with that.
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* 2. Extended memory, accessed per the XMS V2.0 specification.
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* 3. Expanded memory, accessed per the LIM/EMS 4.0 specification.
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* You'll need copies of those specs to make sense of the related code.
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* The specs are available by Internet FTP from the SIMTEL archives
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* (oak.oakland.edu and its various mirror sites). See files
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* pub/msdos/microsoft/xms20.arc and pub/msdos/info/limems41.zip.
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*/
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/*
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* Access methods for a DOS file.
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*/
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METHODDEF void
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read_file_store( j_common_ptr cinfo, backing_store_ptr info,
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void FAR * buffer_address,
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long file_offset, long byte_count ) {
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if ( jdos_seek( info->handle.file_handle, file_offset ) ) {
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ERREXIT( cinfo, JERR_TFILE_SEEK );
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}
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/* Since MAX_ALLOC_CHUNK is less than 64K, byte_count will be too. */
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if ( byte_count > 65535L ) {/* safety check */
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ERREXIT( cinfo, JERR_BAD_ALLOC_CHUNK );
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}
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if ( jdos_read( info->handle.file_handle, buffer_address,
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(unsigned short) byte_count ) ) {
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ERREXIT( cinfo, JERR_TFILE_READ );
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}
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}
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METHODDEF void
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write_file_store( j_common_ptr cinfo, backing_store_ptr info,
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void FAR * buffer_address,
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long file_offset, long byte_count ) {
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if ( jdos_seek( info->handle.file_handle, file_offset ) ) {
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ERREXIT( cinfo, JERR_TFILE_SEEK );
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}
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/* Since MAX_ALLOC_CHUNK is less than 64K, byte_count will be too. */
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if ( byte_count > 65535L ) {/* safety check */
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ERREXIT( cinfo, JERR_BAD_ALLOC_CHUNK );
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}
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if ( jdos_write( info->handle.file_handle, buffer_address,
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(unsigned short) byte_count ) ) {
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ERREXIT( cinfo, JERR_TFILE_WRITE );
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}
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}
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METHODDEF void
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close_file_store( j_common_ptr cinfo, backing_store_ptr info ) {
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jdos_close( info->handle.file_handle );/* close the file */
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remove( info->temp_name );/* delete the file */
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/* If your system doesn't have remove(), try unlink() instead.
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* remove() is the ANSI-standard name for this function, but
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* unlink() was more common in pre-ANSI systems.
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*/
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TRACEMSS( cinfo, 1, JTRC_TFILE_CLOSE, info->temp_name );
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}
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LOCAL boolean
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open_file_store( j_common_ptr cinfo, backing_store_ptr info,
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long total_bytes_needed ) {
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short handle;
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select_file_name( info->temp_name );
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if ( jdos_open( (short far *) &handle, (char far *) info->temp_name ) ) {
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/* might as well exit since jpeg_open_backing_store will fail anyway */
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ERREXITS( cinfo, JERR_TFILE_CREATE, info->temp_name );
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return FALSE;
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}
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info->handle.file_handle = handle;
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info->read_backing_store = read_file_store;
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info->write_backing_store = write_file_store;
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info->close_backing_store = close_file_store;
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TRACEMSS( cinfo, 1, JTRC_TFILE_OPEN, info->temp_name );
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return TRUE; /* succeeded */
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}
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/*
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* Access methods for extended memory.
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*/
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#if XMS_SUPPORTED
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static XMSDRIVER xms_driver; /* saved address of XMS driver */
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typedef union { /* either long offset or real-mode pointer */
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long offset;
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void far * ptr;
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} XMSPTR;
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typedef struct { /* XMS move specification structure */
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long length;
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XMSH src_handle;
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XMSPTR src;
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XMSH dst_handle;
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XMSPTR dst;
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} XMSspec;
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#define ODD( X ) ( ( ( X ) & 1L ) != 0 )
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METHODDEF void
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read_xms_store( j_common_ptr cinfo, backing_store_ptr info,
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void FAR * buffer_address,
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long file_offset, long byte_count ) {
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XMScontext ctx;
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XMSspec spec;
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char endbuffer[2];
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/* The XMS driver can't cope with an odd length, so handle the last byte
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* specially if byte_count is odd. We don't expect this to be common.
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*/
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spec.length = byte_count & ( ~1L );
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spec.src_handle = info->handle.xms_handle;
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spec.src.offset = file_offset;
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spec.dst_handle = 0;
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spec.dst.ptr = buffer_address;
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ctx.ds_si = (void far *) &spec;
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ctx.ax = 0x0b00; /* EMB move */
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jxms_calldriver( xms_driver, (XMScontext far *) &ctx );
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if ( ctx.ax != 1 ) {
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ERREXIT( cinfo, JERR_XMS_READ );
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}
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if ( ODD( byte_count ) ) {
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read_xms_store( cinfo, info, (void FAR *) endbuffer,
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file_offset + byte_count - 1L, 2L );
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( (char FAR *) buffer_address )[byte_count - 1L] = endbuffer[0];
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}
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}
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METHODDEF void
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write_xms_store( j_common_ptr cinfo, backing_store_ptr info,
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void FAR * buffer_address,
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long file_offset, long byte_count ) {
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XMScontext ctx;
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XMSspec spec;
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char endbuffer[2];
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/* The XMS driver can't cope with an odd length, so handle the last byte
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* specially if byte_count is odd. We don't expect this to be common.
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*/
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spec.length = byte_count & ( ~1L );
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spec.src_handle = 0;
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spec.src.ptr = buffer_address;
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spec.dst_handle = info->handle.xms_handle;
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spec.dst.offset = file_offset;
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ctx.ds_si = (void far *) &spec;
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ctx.ax = 0x0b00; /* EMB move */
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jxms_calldriver( xms_driver, (XMScontext far *) &ctx );
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if ( ctx.ax != 1 ) {
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ERREXIT( cinfo, JERR_XMS_WRITE );
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}
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if ( ODD( byte_count ) ) {
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read_xms_store( cinfo, info, (void FAR *) endbuffer,
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file_offset + byte_count - 1L, 2L );
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endbuffer[0] = ( (char FAR *) buffer_address )[byte_count - 1L];
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write_xms_store( cinfo, info, (void FAR *) endbuffer,
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file_offset + byte_count - 1L, 2L );
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}
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}
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METHODDEF void
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close_xms_store( j_common_ptr cinfo, backing_store_ptr info ) {
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XMScontext ctx;
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ctx.dx = info->handle.xms_handle;
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ctx.ax = 0x0a00;
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jxms_calldriver( xms_driver, (XMScontext far *) &ctx );
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TRACEMS1( cinfo, 1, JTRC_XMS_CLOSE, info->handle.xms_handle );
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/* we ignore any error return from the driver */
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}
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LOCAL boolean
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open_xms_store( j_common_ptr cinfo, backing_store_ptr info,
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long total_bytes_needed ) {
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XMScontext ctx;
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/* Get address of XMS driver */
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jxms_getdriver( (XMSDRIVER far *) &xms_driver );
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if ( xms_driver == NULL ) {
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return FALSE;
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} /* no driver to be had */
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/* Get version number, must be >= 2.00 */
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ctx.ax = 0x0000;
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jxms_calldriver( xms_driver, (XMScontext far *) &ctx );
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if ( ctx.ax < (unsigned short) 0x0200 ) {
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return FALSE;
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}
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/* Try to get space (expressed in kilobytes) */
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ctx.dx = (unsigned short) ( ( total_bytes_needed + 1023L ) >> 10 );
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ctx.ax = 0x0900;
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jxms_calldriver( xms_driver, (XMScontext far *) &ctx );
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if ( ctx.ax != 1 ) {
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return FALSE;
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}
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/* Succeeded, save the handle and away we go */
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info->handle.xms_handle = ctx.dx;
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info->read_backing_store = read_xms_store;
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info->write_backing_store = write_xms_store;
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info->close_backing_store = close_xms_store;
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TRACEMS1( cinfo, 1, JTRC_XMS_OPEN, ctx.dx );
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return TRUE; /* succeeded */
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}
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#endif /* XMS_SUPPORTED */
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/*
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* Access methods for expanded memory.
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*/
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#if EMS_SUPPORTED
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/* The EMS move specification structure requires word and long fields aligned
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* at odd byte boundaries. Some compilers will align struct fields at even
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* byte boundaries. While it's usually possible to force byte alignment,
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* that causes an overall performance penalty and may pose problems in merging
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* JPEG into a larger application. Instead we accept some rather dirty code
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* here. Note this code would fail if the hardware did not allow odd-byte
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* word & long accesses, but all 80x86 CPUs do.
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*/
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typedef void far * EMSPTR;
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typedef union { /* EMS move specification structure */
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long length; /* It's easy to access first 4 bytes */
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char bytes[18]; /* Misaligned fields in here! */
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} EMSspec;
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/* Macros for accessing misaligned fields */
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#define FIELD_AT( spec, offset, type ) ( *( (type *) &( spec.bytes[offset] ) ) )
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#define SRC_TYPE( spec ) FIELD_AT( spec, 4, char )
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#define SRC_HANDLE( spec ) FIELD_AT( spec, 5, EMSH )
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#define SRC_OFFSET( spec ) FIELD_AT( spec, 7, unsigned short )
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#define SRC_PAGE( spec ) FIELD_AT( spec, 9, unsigned short )
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#define SRC_PTR( spec ) FIELD_AT( spec, 7, EMSPTR )
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#define DST_TYPE( spec ) FIELD_AT( spec, 11, char )
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#define DST_HANDLE( spec ) FIELD_AT( spec, 12, EMSH )
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#define DST_OFFSET( spec ) FIELD_AT( spec, 14, unsigned short )
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#define DST_PAGE( spec ) FIELD_AT( spec, 16, unsigned short )
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#define DST_PTR( spec ) FIELD_AT( spec, 14, EMSPTR )
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#define EMSPAGESIZE 16384L /* gospel, see the EMS specs */
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#define HIBYTE( W ) ( ( ( W ) >> 8 ) & 0xFF )
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#define LOBYTE( W ) ( ( W ) & 0xFF )
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METHODDEF void
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read_ems_store( j_common_ptr cinfo, backing_store_ptr info,
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void FAR * buffer_address,
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long file_offset, long byte_count ) {
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EMScontext ctx;
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EMSspec spec;
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spec.length = byte_count;
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SRC_TYPE( spec ) = 1;
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SRC_HANDLE( spec ) = info->handle.ems_handle;
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SRC_PAGE( spec ) = (unsigned short) ( file_offset / EMSPAGESIZE );
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SRC_OFFSET( spec ) = (unsigned short) ( file_offset % EMSPAGESIZE );
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DST_TYPE( spec ) = 0;
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DST_HANDLE( spec ) = 0;
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DST_PTR( spec ) = buffer_address;
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ctx.ds_si = (void far *) &spec;
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ctx.ax = 0x5700; /* move memory region */
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jems_calldriver( (EMScontext far *) &ctx );
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if ( HIBYTE( ctx.ax ) != 0 ) {
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ERREXIT( cinfo, JERR_EMS_READ );
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}
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}
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METHODDEF void
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write_ems_store( j_common_ptr cinfo, backing_store_ptr info,
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void FAR * buffer_address,
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long file_offset, long byte_count ) {
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EMScontext ctx;
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EMSspec spec;
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spec.length = byte_count;
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SRC_TYPE( spec ) = 0;
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SRC_HANDLE( spec ) = 0;
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SRC_PTR( spec ) = buffer_address;
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DST_TYPE( spec ) = 1;
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DST_HANDLE( spec ) = info->handle.ems_handle;
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DST_PAGE( spec ) = (unsigned short) ( file_offset / EMSPAGESIZE );
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DST_OFFSET( spec ) = (unsigned short) ( file_offset % EMSPAGESIZE );
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ctx.ds_si = (void far *) &spec;
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ctx.ax = 0x5700; /* move memory region */
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jems_calldriver( (EMScontext far *) &ctx );
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if ( HIBYTE( ctx.ax ) != 0 ) {
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ERREXIT( cinfo, JERR_EMS_WRITE );
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}
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}
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METHODDEF void
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close_ems_store( j_common_ptr cinfo, backing_store_ptr info ) {
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EMScontext ctx;
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ctx.ax = 0x4500;
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ctx.dx = info->handle.ems_handle;
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jems_calldriver( (EMScontext far *) &ctx );
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TRACEMS1( cinfo, 1, JTRC_EMS_CLOSE, info->handle.ems_handle );
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/* we ignore any error return from the driver */
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}
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LOCAL boolean
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open_ems_store( j_common_ptr cinfo, backing_store_ptr info,
|
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long total_bytes_needed ) {
|
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EMScontext ctx;
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|
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/* Is EMS driver there? */
|
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if ( !jems_available() ) {
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return FALSE;
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}
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|
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/* Get status, make sure EMS is OK */
|
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ctx.ax = 0x4000;
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jems_calldriver( (EMScontext far *) &ctx );
|
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if ( HIBYTE( ctx.ax ) != 0 ) {
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return FALSE;
|
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}
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|
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/* Get version, must be >= 4.0 */
|
|
ctx.ax = 0x4600;
|
|
jems_calldriver( (EMScontext far *) &ctx );
|
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if ( ( HIBYTE( ctx.ax ) != 0 ) || ( LOBYTE( ctx.ax ) < 0x40 ) ) {
|
|
return FALSE;
|
|
}
|
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|
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/* Try to allocate requested space */
|
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ctx.ax = 0x4300;
|
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ctx.bx = (unsigned short) ( ( total_bytes_needed + EMSPAGESIZE - 1L ) / EMSPAGESIZE );
|
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jems_calldriver( (EMScontext far *) &ctx );
|
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if ( HIBYTE( ctx.ax ) != 0 ) {
|
|
return FALSE;
|
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}
|
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|
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/* Succeeded, save the handle and away we go */
|
|
info->handle.ems_handle = ctx.dx;
|
|
info->read_backing_store = read_ems_store;
|
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info->write_backing_store = write_ems_store;
|
|
info->close_backing_store = close_ems_store;
|
|
TRACEMS1( cinfo, 1, JTRC_EMS_OPEN, ctx.dx );
|
|
return TRUE; /* succeeded */
|
|
}
|
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|
|
#endif /* EMS_SUPPORTED */
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|
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|
|
/*
|
|
* Initial opening of a backing-store object.
|
|
*/
|
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|
|
GLOBAL void
|
|
jpeg_open_backing_store( j_common_ptr cinfo, backing_store_ptr info,
|
|
long total_bytes_needed ) {
|
|
/* Try extended memory, then expanded memory, then regular file. */
|
|
#if XMS_SUPPORTED
|
|
if ( open_xms_store( cinfo, info, total_bytes_needed ) ) {
|
|
return;
|
|
}
|
|
#endif
|
|
#if EMS_SUPPORTED
|
|
if ( open_ems_store( cinfo, info, total_bytes_needed ) ) {
|
|
return;
|
|
}
|
|
#endif
|
|
if ( open_file_store( cinfo, info, total_bytes_needed ) ) {
|
|
return;
|
|
}
|
|
ERREXITS( cinfo, JERR_TFILE_CREATE, "" );
|
|
}
|
|
|
|
|
|
/*
|
|
* These routines take care of any system-dependent initialization and
|
|
* cleanup required.
|
|
*/
|
|
|
|
GLOBAL long
|
|
jpeg_mem_init( j_common_ptr cinfo ) {
|
|
next_file_num = 0; /* initialize temp file name generator */
|
|
return DEFAULT_MAX_MEM; /* default for max_memory_to_use */
|
|
}
|
|
|
|
GLOBAL void
|
|
jpeg_mem_term( j_common_ptr cinfo ) {
|
|
/* Microsoft C, at least in v6.00A, will not successfully reclaim freed
|
|
* blocks of size > 32Kbytes unless we give it a kick in the rear, like so:
|
|
*/
|
|
#ifdef NEED_FHEAPMIN
|
|
_fheapmin();
|
|
#endif
|
|
}
|