/*
* jmemmac.c
*
* Copyright (C) 1992-1996, 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.
*
* 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 created with
* tmpfile(); that part of the module is the same as in jmemansi.c.
* Metrowerks CodeWarrior's implementation of tmpfile() isn't quite what
* we want: it puts the files in the local directory and makes them
* user-visible -- and only deletes them when the application quits,
* which means they stick around in the event of a crash.
* It would be better to create the temp files in the system's temporary
* items folder. Perhaps someday we'll get around to doing that.
*
* Contributed by Sam Bushell (jsam@iagu.on.net).
*/
#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"
#include "jmemsys.h" /* import the system-dependent declarations */
#include <Memory.h> /* we use the MacOS memory manager */
#ifndef SEEK_SET /* pre-ANSI systems may not define this; */
#define SEEK_SET 0 /* if not, assume 0 is correct */
#endif
/*
* 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)
{
if (fseek(info->temp_file, file_offset, SEEK_SET))
ERREXIT(cinfo, JERR_TFILE_SEEK);
if (JFREAD(info->temp_file, buffer_address, byte_count)
!= (size_t) 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)
{
if (fseek(info->temp_file, file_offset, SEEK_SET))
ERREXIT(cinfo, JERR_TFILE_SEEK);
if (JFWRITE(info->temp_file, buffer_address, byte_count)
!= (size_t) byte_count)
ERREXIT(cinfo, JERR_TFILE_WRITE);
}
METHODDEF(void)
close_backing_store (j_common_ptr cinfo, backing_store_ptr info)
{
fclose(info->temp_file);
/* Since this implementation uses tmpfile() to create the file,
* no explicit file deletion is needed.
*/
}
/*
* Initial opening of a backing-store object.
*
* This version uses tmpfile(), which constructs a suitable file name
* behind the scenes. We don't have to use info->temp_name[] at all;
* indeed, we can't even find out the actual name of the temp file.
*/
GLOBAL(void)
jpeg_open_backing_store (j_common_ptr cinfo, backing_store_ptr info,
long total_bytes_needed)
{
if ((info->temp_file = tmpfile()) == NULL)
ERREXITS(cinfo, JERR_TFILE_CREATE, "");
info->read_backing_store = read_backing_store;
info->write_backing_store = write_backing_store;
info->close_backing_store = close_backing_store;
}
/*
* These routines take care of any system-dependent initialization and
* cleanup required.
*/
GLOBAL(long)
jpeg_mem_init (j_common_ptr cinfo)
{
/* 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 */
}