Alien-FreeImage
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src/Source/LibJPEG/jmemdos.c view on Meta::CPAN
/*
* jmemdos.c
*
* 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 file provides an MS-DOS-compatible implementation of the system-
* dependent portion of the JPEG memory manager. Temporary data can be
* stored in extended or expanded memory as well as in regular DOS files.
*
* If you use this file, you must be sure that NEED_FAR_POINTERS is defined
* if you compile in a small-data memory model; it should NOT be defined if
* you use a large-data memory model. This file is not recommended if you
* are using a flat-memory-space 386 environment such as DJGCC or Watcom C.
* Also, this code will NOT work if struct fields are aligned on greater than
* 2-byte boundaries.
*
* Based on code contributed by Ge' Weijers.
*/
/*
* If you have both extended and expanded memory, you may want to change the
* order in which they are tried in jopen_backing_store. On a 286 machine
* expanded memory is usually faster, since extended memory access involves
* an expensive protected-mode-and-back switch. On 386 and better, extended
* memory is usually faster. As distributed, the code tries extended memory
* first (what? not everyone has a 386? :-).
*
* You can disable use of extended/expanded memory entirely by altering these
* definitions or overriding them from the Makefile (eg, -DEMS_SUPPORTED=0).
*/
#ifndef XMS_SUPPORTED
#define XMS_SUPPORTED 1
#endif
#ifndef EMS_SUPPORTED
#define EMS_SUPPORTED 1
#endif
#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"
#include "jmemsys.h" /* import the system-dependent declarations */
#ifndef HAVE_STDLIB_H /* <stdlib.h> should declare these */
extern void * malloc JPP((size_t size));
extern void free JPP((void *ptr));
extern char * getenv JPP((const char * name));
#endif
#ifdef NEED_FAR_POINTERS
#ifdef __TURBOC__
/* These definitions work for Borland C (Turbo C) */
#include <alloc.h> /* need farmalloc(), farfree() */
#define far_malloc(x) farmalloc(x)
#define far_free(x) farfree(x)
#else
/* These definitions work for Microsoft C and compatible compilers */
#include <malloc.h> /* need _fmalloc(), _ffree() */
#define far_malloc(x) _fmalloc(x)
#define far_free(x) _ffree(x)
#endif
#else /* not NEED_FAR_POINTERS */
#define far_malloc(x) malloc(x)
#define far_free(x) free(x)
#endif /* NEED_FAR_POINTERS */
#ifdef DONT_USE_B_MODE /* define mode parameters for fopen() */
#define READ_BINARY "r"
#else
#define READ_BINARY "rb"
#endif
#ifndef USE_MSDOS_MEMMGR /* make sure user got configuration right */
You forgot to define USE_MSDOS_MEMMGR in jconfig.h. /* deliberate syntax error */
#endif
#if MAX_ALLOC_CHUNK >= 65535L /* make sure jconfig.h got this right */
MAX_ALLOC_CHUNK should be less than 64K. /* deliberate syntax error */
#endif
/*
* Declarations for assembly-language support routines (see jmemdosa.asm).
src/Source/LibJPEG/jmemdos.c view on Meta::CPAN
if (ODD(byte_count)) {
read_xms_store(cinfo, info, (void FAR *) endbuffer,
file_offset + byte_count - 1L, 2L);
endbuffer[0] = ((char FAR *) buffer_address)[byte_count - 1L];
write_xms_store(cinfo, info, (void FAR *) endbuffer,
file_offset + byte_count - 1L, 2L);
}
}
METHODDEF(void)
close_xms_store (j_common_ptr cinfo, backing_store_ptr info)
{
XMScontext ctx;
ctx.dx = info->handle.xms_handle;
ctx.ax = 0x0a00;
jxms_calldriver(xms_driver, (XMScontext far *) & ctx);
TRACEMS1(cinfo, 1, JTRC_XMS_CLOSE, info->handle.xms_handle);
/* we ignore any error return from the driver */
}
LOCAL(boolean)
open_xms_store (j_common_ptr cinfo, backing_store_ptr info,
long total_bytes_needed)
{
XMScontext ctx;
/* Get address of XMS driver */
jxms_getdriver((XMSDRIVER far *) & xms_driver);
if (xms_driver == NULL)
return FALSE; /* no driver to be had */
/* Get version number, must be >= 2.00 */
ctx.ax = 0x0000;
jxms_calldriver(xms_driver, (XMScontext far *) & ctx);
if (ctx.ax < (unsigned short) 0x0200)
return FALSE;
/* Try to get space (expressed in kilobytes) */
ctx.dx = (unsigned short) ((total_bytes_needed + 1023L) >> 10);
ctx.ax = 0x0900;
jxms_calldriver(xms_driver, (XMScontext far *) & ctx);
if (ctx.ax != 1)
return FALSE;
/* Succeeded, save the handle and away we go */
info->handle.xms_handle = ctx.dx;
info->read_backing_store = read_xms_store;
info->write_backing_store = write_xms_store;
info->close_backing_store = close_xms_store;
TRACEMS1(cinfo, 1, JTRC_XMS_OPEN, ctx.dx);
return TRUE; /* succeeded */
}
#endif /* XMS_SUPPORTED */
/*
* Access methods for expanded memory.
*/
#if EMS_SUPPORTED
/* The EMS move specification structure requires word and long fields aligned
* at odd byte boundaries. Some compilers will align struct fields at even
* byte boundaries. While it's usually possible to force byte alignment,
* that causes an overall performance penalty and may pose problems in merging
* JPEG into a larger application. Instead we accept some rather dirty code
* here. Note this code would fail if the hardware did not allow odd-byte
* word & long accesses, but all 80x86 CPUs do.
*/
typedef void far * EMSPTR;
typedef union { /* EMS move specification structure */
long length; /* It's easy to access first 4 bytes */
char bytes[18]; /* Misaligned fields in here! */
} EMSspec;
/* Macros for accessing misaligned fields */
#define FIELD_AT(spec,offset,type) (*((type *) &(spec.bytes[offset])))
#define SRC_TYPE(spec) FIELD_AT(spec,4,char)
#define SRC_HANDLE(spec) FIELD_AT(spec,5,EMSH)
#define SRC_OFFSET(spec) FIELD_AT(spec,7,unsigned short)
#define SRC_PAGE(spec) FIELD_AT(spec,9,unsigned short)
#define SRC_PTR(spec) FIELD_AT(spec,7,EMSPTR)
#define DST_TYPE(spec) FIELD_AT(spec,11,char)
#define DST_HANDLE(spec) FIELD_AT(spec,12,EMSH)
#define DST_OFFSET(spec) FIELD_AT(spec,14,unsigned short)
#define DST_PAGE(spec) FIELD_AT(spec,16,unsigned short)
#define DST_PTR(spec) FIELD_AT(spec,14,EMSPTR)
#define EMSPAGESIZE 16384L /* gospel, see the EMS specs */
#define HIBYTE(W) (((W) >> 8) & 0xFF)
#define LOBYTE(W) ((W) & 0xFF)
METHODDEF(void)
read_ems_store (j_common_ptr cinfo, backing_store_ptr info,
void FAR * buffer_address,
long file_offset, long byte_count)
{
EMScontext ctx;
EMSspec spec;
spec.length = byte_count;
SRC_TYPE(spec) = 1;
SRC_HANDLE(spec) = info->handle.ems_handle;
SRC_PAGE(spec) = (unsigned short) (file_offset / EMSPAGESIZE);
SRC_OFFSET(spec) = (unsigned short) (file_offset % EMSPAGESIZE);
DST_TYPE(spec) = 0;
DST_HANDLE(spec) = 0;
DST_PTR(spec) = buffer_address;
ctx.ds_si = (void far *) & spec;
ctx.ax = 0x5700; /* move memory region */
jems_calldriver((EMScontext far *) & ctx);
if (HIBYTE(ctx.ax) != 0)
src/Source/LibJPEG/jmemdos.c view on Meta::CPAN
{
EMScontext ctx;
ctx.ax = 0x4500;
ctx.dx = info->handle.ems_handle;
jems_calldriver((EMScontext far *) & ctx);
TRACEMS1(cinfo, 1, JTRC_EMS_CLOSE, info->handle.ems_handle);
/* we ignore any error return from the driver */
}
LOCAL(boolean)
open_ems_store (j_common_ptr cinfo, backing_store_ptr info,
long total_bytes_needed)
{
EMScontext ctx;
/* Is EMS driver there? */
if (! jems_available())
return FALSE;
/* Get status, make sure EMS is OK */
ctx.ax = 0x4000;
jems_calldriver((EMScontext far *) & ctx);
if (HIBYTE(ctx.ax) != 0)
return FALSE;
/* Get version, must be >= 4.0 */
ctx.ax = 0x4600;
jems_calldriver((EMScontext far *) & ctx);
if (HIBYTE(ctx.ax) != 0 || LOBYTE(ctx.ax) < 0x40)
return FALSE;
/* Try to allocate requested space */
ctx.ax = 0x4300;
ctx.bx = (unsigned short) ((total_bytes_needed + EMSPAGESIZE-1L) / EMSPAGESIZE);
jems_calldriver((EMScontext far *) & ctx);
if (HIBYTE(ctx.ax) != 0)
return FALSE;
/* Succeeded, save the handle and away we go */
info->handle.ems_handle = ctx.dx;
info->read_backing_store = read_ems_store;
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 */
}
#endif /* EMS_SUPPORTED */
/*
* Initial opening of a backing-store object.
*/
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
}
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