www.pudn.com > imgport.rar > jmemmac.c, change:2008-11-05,size:9796b


/* 
 * jmemmac.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. 
 * 
 * jmemmac.c provides an Apple Macintosh implementation of the system- 
 * dependent portion of the JPEG memory manager. 
 * 
 * If you use jmemmac.c, then you must define USE_MAC_MEMMGR in the 
 * JPEG_INTERNALS part of jconfig.h. 
 * 
 * jmemmac.c uses the Macintosh toolbox routines NewPtr and DisposePtr 
 * instead of malloc and free.  It accurately determines the amount of 
 * memory available by using CompactMem.  Notice that if left to its 
 * own devices, this code can chew up all available space in the 
 * application's zone, with the exception of the rather small "slop" 
 * factor computed in jpeg_mem_available().  The application can ensure 
 * that more space is left over by reducing max_memory_to_use. 
 * 
 * Large images are swapped to disk using temporary files and System 7.0+'s 
 * temporary folder functionality. 
 * 
 * Note that jmemmac.c depends on two features of MacOS that were first 
 * introduced in System 7: FindFolder and the FSSpec-based calls. 
 * If your application uses jmemmac.c and is run under System 6 or earlier, 
 * and the jpeg library decides it needs a temporary file, it will abort, 
 * printing error messages about requiring System 7.  (If no temporary files 
 * are created, it will run fine.) 
 * 
 * If you want to use jmemmac.c in an application that might be used with 
 * System 6 or earlier, then you should remove dependencies on FindFolder 
 * and the FSSpec calls.  You will need to replace FindFolder with some 
 * other mechanism for finding a place to put temporary files, and you 
 * should replace the FSSpec calls with their HFS equivalents: 
 * 
 *     FSpDelete     ->  HDelete 
 *     FSpGetFInfo   ->  HGetFInfo 
 *     FSpCreate     ->  HCreate 
 *     FSpOpenDF     ->  HOpen      *** Note: not HOpenDF *** 
 *     FSMakeFSSpec  ->  (fill in spec by hand.) 
 * 
 * (Use HOpen instead of HOpenDF.  HOpen is just a glue-interface to PBHOpen, 
 * which is on all HFS macs.  HOpenDF is a System 7 addition which avoids the 
 * ages-old problem of names starting with a period.) 
 * 
 * Contributed by Sam Bushell (jsam@iagu.on.net) and 
 * Dan Gildor (gyld@in-touch.com). 
 */ 
 
#define JPEG_INTERNALS 
#include "jinclude.h" 
#include "jpeglib.h" 
#include "jmemsys.h"    /* import the system-dependent declarations */ 
 
#ifndef USE_MAC_MEMMGR	/* make sure user got configuration right */ 
  You forgot to define USE_MAC_MEMMGR in jconfig.h. /* deliberate syntax error */ 
#endif 
 
#include <Memory.h>     /* we use the MacOS memory manager */ 
#include <Files.h>      /* we use the MacOS File stuff */ 
#include <Folders.h>    /* we use the MacOS HFS stuff */ 
#include <Script.h>     /* for smSystemScript */ 
#include <Gestalt.h>    /* we use Gestalt to test for specific functionality */ 
 
#ifndef TEMP_FILE_NAME		/* can override from jconfig.h or Makefile */ 
#define TEMP_FILE_NAME  "JPG%03d.TMP" 
#endif 
 
static int next_file_num;	/* to distinguish among several temp files */ 
 
 
/* 
 * Memory allocation and freeing are controlled by the MacOS library 
 * routines NewPtr() and DisposePtr(), which allocate fixed-address 
 * storage.  Unfortunately, the IJG library isn't smart enough to cope 
 * with relocatable storage. 
 */ 
 
GLOBAL(void *) 
jpeg_get_small (j_common_ptr cinfo, size_t sizeofobject) 
{ 
  return (void *) NewPtr(sizeofobject); 
} 
 
GLOBAL(void) 
jpeg_free_small (j_common_ptr cinfo, void * object, size_t sizeofobject) 
{ 
  DisposePtr((Ptr) object); 
} 
 
 
/* 
 * "Large" objects are treated the same as "small" ones. 
 * NB: we include FAR keywords in the routine declarations simply for 
 * consistency with the rest of the IJG code; FAR should expand to empty 
 * on rational architectures like the Mac. 
 */ 
 
GLOBAL(void FAR *) 
jpeg_get_large (j_common_ptr cinfo, size_t sizeofobject) 
{ 
  return (void FAR *) NewPtr(sizeofobject); 
} 
 
GLOBAL(void) 
jpeg_free_large (j_common_ptr cinfo, void FAR * object, size_t sizeofobject) 
{ 
  DisposePtr((Ptr) object); 
} 
 
 
/* 
 * This routine computes the total memory space available for allocation. 
 */ 
 
GLOBAL(long) 
jpeg_mem_available (j_common_ptr cinfo, long min_bytes_needed, 
		    long max_bytes_needed, long already_allocated) 
{ 
  long limit = cinfo->mem->max_memory_to_use - already_allocated; 
  long slop, mem; 
 
  /* Don't ask for more than what application has told us we may use */ 
  if (max_bytes_needed > limit && limit > 0) 
    max_bytes_needed = limit; 
  /* Find whether there's a big enough free block in the heap. 
   * CompactMem tries to create a contiguous block of the requested size, 
   * and then returns the size of the largest free block (which could be 
   * much more or much less than we asked for). 
   * We add some slop to ensure we don't use up all available memory. 
   */ 
  slop = max_bytes_needed / 16 + 32768L; 
  mem = CompactMem(max_bytes_needed + slop) - slop; 
  if (mem < 0) 
    mem = 0;			/* sigh, couldn't even get the slop */ 
  /* Don't take more than the application says we can have */ 
  if (mem > limit && limit > 0) 
    mem = limit; 
  return mem; 
} 
 
 
/* 
 * Backing store (temporary file) management. 
 * Backing store objects are only used when the value returned by 
 * jpeg_mem_available is less than the total space needed.  You can dispense 
 * with these routines if you have plenty of virtual memory; see jmemnobs.c. 
 */ 
 
 
METHODDEF(void) 
read_backing_store (j_common_ptr cinfo, backing_store_ptr info, 
		    void FAR * buffer_address, 
		    long file_offset, long byte_count) 
{ 
  long bytes = byte_count; 
  long retVal; 
 
  if ( SetFPos ( info->temp_file, fsFromStart, file_offset ) != noErr ) 
    ERREXIT(cinfo, JERR_TFILE_SEEK); 
 
  retVal = FSRead ( info->temp_file, &bytes, 
		    (unsigned char *) buffer_address ); 
  if ( retVal != noErr || bytes != byte_count ) 
    ERREXIT(cinfo, JERR_TFILE_READ); 
} 
 
 
METHODDEF(void) 
write_backing_store (j_common_ptr cinfo, backing_store_ptr info, 
		     void FAR * buffer_address, 
		     long file_offset, long byte_count) 
{ 
  long bytes = byte_count; 
  long retVal; 
 
  if ( SetFPos ( info->temp_file, fsFromStart, file_offset ) != noErr ) 
    ERREXIT(cinfo, JERR_TFILE_SEEK); 
 
  retVal = FSWrite ( info->temp_file, &bytes, 
		     (unsigned char *) buffer_address ); 
  if ( retVal != noErr || bytes != byte_count ) 
    ERREXIT(cinfo, JERR_TFILE_WRITE); 
} 
 
 
METHODDEF(void) 
close_backing_store (j_common_ptr cinfo, backing_store_ptr info) 
{ 
  FSClose ( info->temp_file ); 
  FSpDelete ( &(info->tempSpec) ); 
} 
 
 
/* 
 * Initial opening of a backing-store object. 
 * 
 * This version uses FindFolder to find the Temporary Items folder, 
 * and puts the temporary file in there. 
 */ 
 
GLOBAL(void) 
jpeg_open_backing_store (j_common_ptr cinfo, backing_store_ptr info, 
			 long total_bytes_needed) 
{ 
  short         tmpRef, vRefNum; 
  long          dirID; 
  FInfo         finderInfo; 
  FSSpec        theSpec; 
  Str255        fName; 
  OSErr         osErr; 
  long          gestaltResponse = 0; 
 
  /* Check that FSSpec calls are available. */ 
  osErr = Gestalt( gestaltFSAttr, &gestaltResponse ); 
  if ( ( osErr != noErr ) 
       || !( gestaltResponse & (1<<gestaltHasFSSpecCalls) ) ) 
    ERREXITS(cinfo, JERR_TFILE_CREATE, "- System 7.0 or later required"); 
  /* TO DO: add a proper error message to jerror.h. */ 
 
  /* Check that FindFolder is available. */ 
  osErr = Gestalt( gestaltFindFolderAttr, &gestaltResponse ); 
  if ( ( osErr != noErr ) 
       || !( gestaltResponse & (1<<gestaltFindFolderPresent) ) ) 
    ERREXITS(cinfo, JERR_TFILE_CREATE, "- System 7.0 or later required."); 
  /* TO DO: add a proper error message to jerror.h. */ 
 
  osErr = FindFolder ( kOnSystemDisk, kTemporaryFolderType, kCreateFolder, 
                       &vRefNum, &dirID ); 
  if ( osErr != noErr ) 
    ERREXITS(cinfo, JERR_TFILE_CREATE, "- temporary items folder unavailable"); 
  /* TO DO: Try putting the temp files somewhere else. */ 
 
  /* Keep generating file names till we find one that's not in use */ 
  for (;;) { 
    next_file_num++;		/* advance counter */ 
 
    sprintf(info->temp_name, TEMP_FILE_NAME, next_file_num); 
    strcpy ( (Ptr)fName+1, info->temp_name ); 
    *fName = strlen (info->temp_name); 
    osErr = FSMakeFSSpec ( vRefNum, dirID, fName, &theSpec ); 
 
    if ( (osErr = FSpGetFInfo ( &theSpec, &finderInfo ) ) != noErr ) 
      break; 
  } 
 
  osErr = FSpCreate ( &theSpec, '????', '????', smSystemScript ); 
  if ( osErr != noErr ) 
    ERREXITS(cinfo, JERR_TFILE_CREATE, info->temp_name); 
 
  osErr = FSpOpenDF ( &theSpec, fsRdWrPerm, &(info->temp_file) ); 
  if ( osErr != noErr ) 
    ERREXITS(cinfo, JERR_TFILE_CREATE, info->temp_name); 
 
  info->tempSpec = theSpec; 
 
  info->read_backing_store = read_backing_store; 
  info->write_backing_store = write_backing_store; 
  info->close_backing_store = close_backing_store; 
  TRACEMSS(cinfo, 1, JTRC_TFILE_OPEN, info->temp_name); 
} 
 
 
/* 
 * 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; 
 
  /* max_memory_to_use will be initialized to FreeMem()'s result; 
   * the calling application might later reduce it, for example 
   * to leave room to invoke multiple JPEG objects. 
   * Note that FreeMem returns the total number of free bytes; 
   * it may not be possible to allocate a single block of this size. 
   */ 
  return FreeMem(); 
} 
 
GLOBAL(void) 
jpeg_mem_term (j_common_ptr cinfo) 
{ 
  /* no work */ 
}