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/*
* jvirtmem.c
*
* Copyright (C) 1991, 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 the system-dependent memory allocation routines
* for the case where we can rely on virtual memory to handle large arrays.
*
* This includes some MS-DOS code just for trial purposes; "big" arrays will
* have to be handled with temp files on MS-DOS, so a real implementation of
* a DOS memory manager will probably be a separate file. (See additional
* comments about big arrays, below.)
*
* NB: allocation routines never return NULL.
* They should exit to error_exit if unsuccessful.
*/
#include "jinclude.h"
#ifdef __STDC__
#include <stdlib.h> /* to declare malloc(), free() */
#else
extern void * malloc PP((size_t size));
extern void free PP((void *ptr));
#endif
/* Insert system-specific definitions of far_malloc, far_free here. */
#ifndef NEED_FAR_POINTERS /* Generic for non-braindamaged CPUs */
#define far_malloc(x) malloc(x)
#define far_free(x) free(x)
#else /* NEED_FAR_POINTERS */
#ifdef __TURBOC__
/* These definitions work for Turbo C */
#include <alloc.h> /* need farmalloc(), farfree() */
#define far_malloc(x) farmalloc(x)
#define far_free(x) farfree(x)
#else
#ifdef MSDOS
/* 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
#endif
#endif /* NEED_FAR_POINTERS */
/*
* Some important notes:
* The array alloc/dealloc routines are not merely a convenience;
* on 80x86 machines the bottom-level pointers in an array are FAR
* and thus may not be allocatable by alloc_small.
*
* Also, it's not a good idea to try to merge the sarray and barray
* routines, even though they are textually almost the same, because
* samples are usually stored as bytes while coefficients are shorts.
* Thus, in machines where byte pointers have a different representation
* from word pointers, the resulting machine code could not be the same.
*/
static external_methods_ptr methods; /* saved for access to error_exit */
#ifdef MEM_STATS /* optional extra stuff for statistics */
#define MALLOC_OVERHEAD (SIZEOF(char *)) /* assumed overhead per request */
#define MALLOC_FAR_OVERHEAD (SIZEOF(char FAR *)) /* for "far" storage */
static long total_num_small = 0; /* total # of small objects alloced */
static long total_bytes_small = 0; /* total bytes requested */
static long cur_num_small = 0; /* # currently alloced */
static long max_num_small = 0; /* max simultaneously alloced */
#ifdef NEED_FAR_POINTERS
static long total_num_medium = 0; /* total # of medium objects alloced */
static long total_bytes_medium = 0; /* total bytes requested */
static long cur_num_medium = 0; /* # currently alloced */
static long max_num_medium = 0; /* max simultaneously alloced */
#endif
static long total_num_sarray = 0; /* total # of sarray objects alloced */
static long total_bytes_sarray = 0; /* total bytes requested */
static long cur_num_sarray = 0; /* # currently alloced */
static long max_num_sarray = 0; /* max simultaneously alloced */
static long total_num_barray = 0; /* total # of barray objects alloced */
static long total_bytes_barray = 0; /* total bytes requested */
static long cur_num_barray = 0; /* # currently alloced */
static long max_num_barray = 0; /* max simultaneously alloced */
GLOBAL void
j_mem_stats (void)
{
/* since this is only a debugging stub, we can cheat a little on the
* trace message mechanism... helps 'cuz trace can't handle longs.
*/
fprintf(stderr, "total_num_small = %ld\n", total_num_small);
fprintf(stderr, "total_bytes_small = %ld\n", total_bytes_small);
if (cur_num_small)
fprintf(stderr, "CUR_NUM_SMALL = %ld\n", cur_num_small);
fprintf(stderr, "max_num_small = %ld\n", max_num_small);
#ifdef NEED_FAR_POINTERS
fprintf(stderr, "total_num_medium = %ld\n", total_num_medium);
fprintf(stderr, "total_bytes_medium = %ld\n", total_bytes_medium);
if (cur_num_medium)
fprintf(stderr, "CUR_NUM_MEDIUM = %ld\n", cur_num_medium);
fprintf(stderr, "max_num_medium = %ld\n", max_num_medium);
#endif
fprintf(stderr, "total_num_sarray = %ld\n", total_num_sarray);
fprintf(stderr, "total_bytes_sarray = %ld\n", total_bytes_sarray);
if (cur_num_sarray)
fprintf(stderr, "CUR_NUM_SARRAY = %ld\n", cur_num_sarray);
fprintf(stderr, "max_num_sarray = %ld\n", max_num_sarray);
fprintf(stderr, "total_num_barray = %ld\n", total_num_barray);
fprintf(stderr, "total_bytes_barray = %ld\n", total_bytes_barray);
if (cur_num_barray)
fprintf(stderr, "CUR_NUM_BARRAY = %ld\n", cur_num_barray);
fprintf(stderr, "max_num_barray = %ld\n", max_num_barray);
}
#endif /* MEM_STATS */
LOCAL void
out_of_memory (int which)
/* Report an out-of-memory error and stop execution */
/* If we compiled MEM_STATS support, report alloc requests before dying */
{
#ifdef MEM_STATS
j_mem_stats();
#endif
ERREXIT1(methods, "Insufficient memory (case %d)", which);
}
METHODDEF void *
alloc_small (size_t sizeofobject)
/* Allocate a "small" (all-in-memory) object */
{
void * result;
#ifdef MEM_STATS
total_num_small++;
total_bytes_small += sizeofobject + MALLOC_OVERHEAD;
cur_num_small++;
if (cur_num_small > max_num_small) max_num_small = cur_num_small;
#endif
result = malloc(sizeofobject);
if (result == NULL)
out_of_memory(1);
return result;
}
METHODDEF void
free_small (void *ptr)
/* Free a "small" (all-in-memory) object */
{
free(ptr);
#ifdef MEM_STATS
cur_num_small--;
#endif
}
#ifdef NEED_FAR_POINTERS
METHODDEF void FAR *
alloc_medium (size_t sizeofobject)
/* Allocate a "medium" (all in memory, but in far heap) object */
{
void FAR * result;
#ifdef MEM_STATS
total_num_medium++;
total_bytes_medium += sizeofobject + MALLOC_FAR_OVERHEAD;
cur_num_medium++;
if (cur_num_medium > max_num_medium) max_num_medium = cur_num_medium;
#endif
result = far_malloc(sizeofobject);
if (result == NULL)
out_of_memory(2);
return result;
}
METHODDEF void
free_medium (void FAR *ptr)
/* Free a "medium" (all in memory, but in far heap) object */
{
far_free(ptr);
#ifdef MEM_STATS
cur_num_medium--;
#endif
}
#endif /* NEED_FAR_POINTERS */
METHODDEF JSAMPARRAY
alloc_small_sarray (long samplesperrow, long numrows)
/* Allocate a "small" (all-in-memory) 2-D sample array */
{
JSAMPARRAY result;
long i;
#ifdef MEM_STATS
total_num_sarray++;
total_bytes_sarray += (samplesperrow * SIZEOF(JSAMPLE) + MALLOC_FAR_OVERHEAD)
* numrows;
cur_num_sarray++;
if (cur_num_sarray > max_num_sarray) max_num_sarray = cur_num_sarray;
#endif
/* Get space for row pointers; this is always "near" on 80x86 */
result = (JSAMPARRAY) alloc_small((size_t) (numrows * SIZEOF(JSAMPROW)));
/* Get the rows themselves; on 80x86 these are "far" */
for (i = 0; i < numrows; i++) {
result[i] = (JSAMPROW) far_malloc((size_t) (samplesperrow * SIZEOF(JSAMPLE)));
if (result[i] == NULL)
out_of_memory(3);
}
return result;
}
METHODDEF void
free_small_sarray (JSAMPARRAY ptr, long numrows)
/* Free a "small" (all-in-memory) 2-D sample array */
{
long i;
/* Free the rows themselves; on 80x86 these are "far" */
for (i = 0; i < numrows; i++) {
far_free((void FAR *) ptr[i]);
}
/* Free space for row pointers; this is always "near" on 80x86 */
free_small((void *) ptr);
#ifdef MEM_STATS
cur_num_sarray--;
#endif
}
METHODDEF JBLOCKARRAY
alloc_small_barray (long blocksperrow, long numrows)
/* Allocate a "small" (all-in-memory) 2-D coefficient-block array */
{
JBLOCKARRAY result;
long i;
#ifdef MEM_STATS
total_num_barray++;
total_bytes_barray += (blocksperrow * SIZEOF(JBLOCK) + MALLOC_FAR_OVERHEAD)
* numrows;
cur_num_barray++;
if (cur_num_barray > max_num_barray) max_num_barray = cur_num_barray;
#endif
/* Get space for row pointers; this is always "near" on 80x86 */
result = (JBLOCKARRAY) alloc_small((size_t) (numrows * SIZEOF(JBLOCKROW)));
/* Get the rows themselves; on 80x86 these are "far" */
for (i = 0; i < numrows; i++) {
result[i] = (JBLOCKROW) far_malloc((size_t) (blocksperrow * SIZEOF(JBLOCK)));
if (result[i] == NULL)
out_of_memory(4);
}
return result;
}
METHODDEF void
free_small_barray (JBLOCKARRAY ptr, long numrows)
/* Free a "small" (all-in-memory) 2-D coefficient-block array */
{
long i;
/* Free the rows themselves; on 80x86 these are "far" */
for (i = 0; i < numrows; i++) {
far_free((void FAR *) ptr[i]);
}
/* Free space for row pointers; this is always "near" on 80x86 */
free_small((void *) ptr);
#ifdef MEM_STATS
cur_num_barray--;
#endif
}
/*
* About "big" array management:
*
* To allow machines with limited memory to handle large images,
* all processing in the JPEG system is done a few pixel or block rows
* at a time. The above "small" array routines are only used to allocate
* strip buffers (as wide as the image, but just a few rows high).
* In some cases multiple passes must be made over the data. In these
* cases the "big" array routines are used. The array is still accessed
* a strip at a time, but the memory manager must save the whole array
* for repeated accesses. The intended implementation is that there is
* a strip buffer in memory (as high as is possible given the desired memory
* limit), plus a backing file that holds the rest of the array.
*
* The request_big_array routines are told the total size of the image (in case
* it is useful to know the total file size that will be needed). They are
* also given the unit height, which is the number of rows that will be
* accessed at once; the in-memory buffer should usually be made a multiple of
* this height for best efficiency.
*
* The request routines create control blocks (and may open backing files),
* but they don't create the in-memory buffers. This is postponed until
* alloc_big_arrays is called. At that time the total amount of space needed
* is known (approximately, anyway), so free memory can be divided up fairly.
*
* The access_big_array routines are responsible for making a specific strip
* area accessible (after reading or writing the backing file, if necessary).
* Note that the access routines are told whether the caller intends to modify
* the accessed strip; during a read-only pass this saves having to rewrite
* data to disk.
*
* The typical access pattern is one top-to-bottom pass to write the data,
* followed by one or more read-only top-to-bottom passes. However, other
* access patterns may occur while reading. For example, translation of image
* formats that use bottom-to-top scan order will require bottom-to-top read
* passes. The memory manager need not support multiple write passes nor
* funny write orders (meaning that rearranging rows must be handled while
* reading data out of the big array, not while putting it in).
*
* In current usage, the access requests are always for nonoverlapping strips;
* that is, successive access start_row numbers always differ by exactly the
* unitheight. This allows fairly simple buffer dump/reload logic if the
* in-memory buffer is made a multiple of the unitheight. It would be
* possible to keep subsampled rather than fullsize data in the "big" arrays,
* thus reducing temp file size, if we supported overlapping strip access
* (access requests differing by less than the unitheight). At the moment
* I don't believe this is worth the extra complexity.
*
* This particular implementation doesn't use temp files; the whole of a big
* array is allocated in (virtual) memory, and any swapping is done behind the
* scenes by the operating system.
*/
/* The control blocks for virtual arrays.
* These are pretty minimal in this implementation.
* Note: in this implementation we could realize big arrays
* at request time and make alloc_big_arrays a no-op;
* however, doing it separately keeps callers honest.
*/
struct big_sarray_control {
JSAMPARRAY mem_buffer; /* memory buffer (the whole thing, here) */
long rows_in_mem; /* Height of memory buffer */
long samplesperrow; /* Width of memory buffer */
long unitheight; /* # of rows accessed by access_big_sarray() */
big_sarray_ptr next; /* list link for unrealized arrays */
};
struct big_barray_control {
JBLOCKARRAY mem_buffer; /* memory buffer (the whole thing, here) */
long rows_in_mem; /* Height of memory buffer */
long blocksperrow; /* Width of memory buffer */
long unitheight; /* # of rows accessed by access_big_barray() */
big_barray_ptr next; /* list link for unrealized arrays */
};
/* Headers of lists of control blocks for unrealized big arrays */
static big_sarray_ptr unalloced_sarrays;
static big_barray_ptr unalloced_barrays;
METHODDEF big_sarray_ptr
request_big_sarray (long samplesperrow, long numrows, long unitheight)
/* Request a "big" (virtual-memory) 2-D sample array */
{
big_sarray_ptr result;
/* get control block */
result = (big_sarray_ptr) alloc_small(SIZEOF(struct big_sarray_control));
result->mem_buffer = NULL; /* lets access routine spot premature access */
result->rows_in_mem = numrows;
result->samplesperrow = samplesperrow;
result->unitheight = unitheight;
result->next = unalloced_sarrays; /* add to list of unallocated arrays */
unalloced_sarrays = result;
return result;
}
METHODDEF big_barray_ptr
request_big_barray (long blocksperrow, long numrows, long unitheight)
/* Request a "big" (virtual-memory) 2-D coefficient-block array */
{
big_barray_ptr result;
/* get control block */
result = (big_barray_ptr) alloc_small(SIZEOF(struct big_barray_control));
result->mem_buffer = NULL; /* lets access routine spot premature access */
result->rows_in_mem = numrows;
result->blocksperrow = blocksperrow;
result->unitheight = unitheight;
result->next = unalloced_barrays; /* add to list of unallocated arrays */
unalloced_barrays = result;
return result;
}
METHODDEF void
alloc_big_arrays (long extra_small_samples, long extra_small_blocks,
long extra_medium_space)
/* Allocate the in-memory buffers for any unrealized "big" arrays */
/* 'extra' values are upper bounds for total future small-array requests */
/* and far-heap requests */
{
/* In this implementation we just malloc the whole arrays */
/* and expect the system's virtual memory to worry about swapping them */
big_sarray_ptr sptr;
big_barray_ptr bptr;
for (sptr = unalloced_sarrays; sptr != NULL; sptr = sptr->next) {
sptr->mem_buffer = alloc_small_sarray(sptr->samplesperrow,
sptr->rows_in_mem);
}
for (bptr = unalloced_barrays; bptr != NULL; bptr = bptr->next) {
bptr->mem_buffer = alloc_small_barray(bptr->blocksperrow,
bptr->rows_in_mem);
}
unalloced_sarrays = NULL; /* reset for possible future cycles */
unalloced_barrays = NULL;
}
METHODDEF JSAMPARRAY
access_big_sarray (big_sarray_ptr ptr, long start_row, boolean writable)
/* Access the part of a "big" sample array starting at start_row */
/* and extending for ptr->unitheight rows. writable is true if */
/* caller intends to modify the accessed area. */
{
/* debugging check */
if (start_row < 0 || start_row+ptr->unitheight > ptr->rows_in_mem ||
ptr->mem_buffer == NULL)
ERREXIT(methods, "Bogus access_big_sarray request");
return ptr->mem_buffer + start_row;
}
METHODDEF JBLOCKARRAY
access_big_barray (big_barray_ptr ptr, long start_row, boolean writable)
/* Access the part of a "big" coefficient-block array starting at start_row */
/* and extending for ptr->unitheight rows. writable is true if */
/* caller intends to modify the accessed area. */
{
/* debugging check */
if (start_row < 0 || start_row+ptr->unitheight > ptr->rows_in_mem ||
ptr->mem_buffer == NULL)
ERREXIT(methods, "Bogus access_big_barray request");
return ptr->mem_buffer + start_row;
}
METHODDEF void
free_big_sarray (big_sarray_ptr ptr)
/* Free a "big" (virtual-memory) 2-D sample array */
{
free_small_sarray(ptr->mem_buffer, ptr->rows_in_mem);
free_small((void *) ptr); /* free the control block too */
}
METHODDEF void
free_big_barray (big_barray_ptr ptr)
/* Free a "big" (virtual-memory) 2-D coefficient-block array */
{
free_small_barray(ptr->mem_buffer, ptr->rows_in_mem);
free_small((void *) ptr); /* free the control block too */
}
/*
* The method selection routine for virtual memory systems.
* The system-dependent setup routine should call this routine
* to install the necessary method pointers in the supplied struct.
*/
GLOBAL void
jselvirtmem (external_methods_ptr emethods)
{
methods = emethods; /* save struct addr for error exit access */
emethods->alloc_small = alloc_small;
emethods->free_small = free_small;
#ifdef NEED_FAR_POINTERS
emethods->alloc_medium = alloc_medium;
emethods->free_medium = free_medium;
#endif
emethods->alloc_small_sarray = alloc_small_sarray;
emethods->free_small_sarray = free_small_sarray;
emethods->alloc_small_barray = alloc_small_barray;
emethods->free_small_barray = free_small_barray;
emethods->request_big_sarray = request_big_sarray;
emethods->request_big_barray = request_big_barray;
emethods->alloc_big_arrays = alloc_big_arrays;
emethods->access_big_sarray = access_big_sarray;
emethods->access_big_barray = access_big_barray;
emethods->free_big_sarray = free_big_sarray;
emethods->free_big_barray = free_big_barray;
unalloced_sarrays = NULL; /* make sure list headers are empty */
unalloced_barrays = NULL;
}
These are the contents of the former NiCE NeXT User Group NeXTSTEP/OpenStep software archive, currently hosted by Netfuture.ch.