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src/Source/LibJPEG/jmemmac.c  view on Meta::CPAN

 * 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 */