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- /*
- * 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 */
- }
-