source: golgotha/src/i4/loaders/jpg/jmemmgr.cc @ 80

Last change on this file since 80 was 80, checked in by Sam Hocevar, 12 years ago
  • Adding the Golgotha source code. Not sure what's going to be interesting in there, but since it's all public domain, there's certainly stuff to pick up.
File size: 41.5 KB
Line 
1/********************************************************************** <BR>
2  This file is part of Crack dot Com's free source code release of
3  Golgotha. <a href="http://www.crack.com/golgotha_release"> <BR> for
4  information about compiling & licensing issues visit this URL</a>
5  <PRE> If that doesn't help, contact Jonathan Clark at
6  golgotha_source@usa.net (Subject should have "GOLG" in it)
7***********************************************************************/
8
9/*
10 * jmemmgr.c
11 *
12 * Copyright (C) 1991-1996, Thomas G. Lane.
13 * This file is part of the Independent JPEG Group's software.
14 * For conditions of distribution and use, see the accompanying README file.
15 *
16 * This file contains the JPEG system-independent memory management
17 * routines.  This code is usable across a wide variety of machines; most
18 * of the system dependencies have been isolated in a separate file.
19 * The major functions provided here are:
20 *   * pool-based allocation and freeing of memory;
21 *   * policy decisions about how to divide available memory among the
22 *     virtual arrays;
23 *   * control logic for swapping virtual arrays between main memory and
24 *     backing storage.
25 * The separate system-dependent file provides the actual backing-storage
26 * access code, and it contains the policy decision about how much total
27 * main memory to use.
28 * This file is system-dependent in the sense that some of its functions
29 * are unnecessary in some systems.  For example, if there is enough virtual
30 * memory so that backing storage will never be used, much of the virtual
31 * array control logic could be removed.  (Of course, if you have that much
32 * memory then you shouldn't care about a little bit of unused code...)
33 */
34
35#define JPEG_INTERNALS
36#define AM_MEMORY_MANAGER       /* we define jvirt_Xarray_control structs */
37#include "loaders/jpg/jinclude.h"
38#include "loaders/jpg/jpeglib.h"
39#include "loaders/jpg/jmemsys.h"                /* import the system-dependent declarations */
40
41#ifndef NO_GETENV
42#ifndef HAVE_STDLIB_H           /* <stdlib.h> should declare getenv() */
43extern char * getenv JPP((const char * name));
44#endif
45#endif
46
47
48/*
49 * Some important notes:
50 *   The allocation routines provided here must never return NULL.
51 *   They should exit to error_exit if unsuccessful.
52 *
53 *   It's not a good idea to try to merge the sarray and barray routines,
54 *   even though they are textually almost the same, because samples are
55 *   usually stored as bytes while coefficients are shorts or ints.  Thus,
56 *   in machines where byte pointers have a different representation from
57 *   word pointers, the resulting machine code could not be the same.
58 */
59
60
61/*
62 * Many machines require storage alignment: longs must start on 4-byte
63 * boundaries, doubles on 8-byte boundaries, etc.  On such machines, malloc()
64 * always returns pointers that are multiples of the worst-case alignment
65 * requirement, and we had better do so too.
66 * There isn't any really portable way to determine the worst-case alignment
67 * requirement.  This module assumes that the alignment requirement is
68 * multiples of sizeof(ALIGN_TYPE).
69 * By default, we define ALIGN_TYPE as double.  This is necessary on some
70 * workstations (where doubles really do need 8-byte alignment) and will work
71 * fine on nearly everything.  If your machine has lesser alignment needs,
72 * you can save a few bytes by making ALIGN_TYPE smaller.
73 * The only place I know of where this will NOT work is certain Macintosh
74 * 680x0 compilers that define double as a 10-byte IEEE extended float.
75 * Doing 10-byte alignment is counterproductive because longwords won't be
76 * aligned well.  Put "#define ALIGN_TYPE long" in jconfig.h if you have
77 * such a compiler.
78 */
79
80#ifndef ALIGN_TYPE              /* so can override from jconfig.h */
81#define ALIGN_TYPE  double
82#endif
83
84
85/*
86 * We allocate objects from "pools", where each pool is gotten with a single
87 * request to jpeg_get_small() or jpeg_get_large().  There is no per-object
88 * overhead within a pool, except for alignment padding.  Each pool has a
89 * header with a link to the next pool of the same class.
90 * Small and large pool headers are identical except that the latter's
91 * link pointer must be FAR on 80x86 machines.
92 * Notice that the "real" header fields are union'ed with a dummy ALIGN_TYPE
93 * field.  This forces the compiler to make SIZEOF(small_pool_hdr) a multiple
94 * of the alignment requirement of ALIGN_TYPE.
95 */
96
97typedef union small_pool_struct * small_pool_ptr;
98
99typedef union small_pool_struct {
100  struct {
101    small_pool_ptr next;        /* next in list of pools */
102    size_t bytes_used;          /* how many bytes already used within pool */
103    size_t bytes_left;          /* bytes still available in this pool */
104  } hdr;
105  ALIGN_TYPE dummy;             /* included in union to ensure alignment */
106} small_pool_hdr;
107
108typedef union large_pool_struct FAR * large_pool_ptr;
109
110typedef union large_pool_struct {
111  struct {
112    large_pool_ptr next;        /* next in list of pools */
113    size_t bytes_used;          /* how many bytes already used within pool */
114    size_t bytes_left;          /* bytes still available in this pool */
115  } hdr;
116  ALIGN_TYPE dummy;             /* included in union to ensure alignment */
117} large_pool_hdr;
118
119
120/*
121 * Here is the full definition of a memory manager object.
122 */
123
124typedef struct {
125  struct jpeg_memory_mgr pub;   /* public fields */
126
127  /* Each pool identifier (lifetime class) names a linked list of pools. */
128  small_pool_ptr small_list[JPOOL_NUMPOOLS];
129  large_pool_ptr large_list[JPOOL_NUMPOOLS];
130
131  /* Since we only have one lifetime class of virtual arrays, only one
132   * linked list is necessary (for each datatype).  Note that the virtual
133   * array control blocks being linked together are actually stored somewhere
134   * in the small-pool list.
135   */
136  jvirt_sarray_ptr virt_sarray_list;
137  jvirt_barray_ptr virt_barray_list;
138
139  /* This counts total space obtained from jpeg_get_small/large */
140  long total_space_allocated;
141
142  /* alloc_sarray and alloc_barray set this value for use by virtual
143   * array routines.
144   */
145  JDIMENSION last_rowsperchunk; /* from most recent alloc_sarray/barray */
146} my_memory_mgr;
147
148typedef my_memory_mgr * my_mem_ptr;
149
150
151/*
152 * The control blocks for virtual arrays.
153 * Note that these blocks are allocated in the "small" pool area.
154 * System-dependent info for the associated backing store (if any) is hidden
155 * inside the backing_store_info struct.
156 */
157
158struct jvirt_sarray_control {
159  JSAMPARRAY mem_buffer;        /* => the in-memory buffer */
160  JDIMENSION rows_in_array;     /* total virtual array height */
161  JDIMENSION samplesperrow;     /* width of array (and of memory buffer) */
162  JDIMENSION maxaccess;         /* max rows accessed by access_virt_sarray */
163  JDIMENSION rows_in_mem;       /* height of memory buffer */
164  JDIMENSION rowsperchunk;      /* allocation chunk size in mem_buffer */
165  JDIMENSION cur_start_row;     /* first logical row # in the buffer */
166  JDIMENSION first_undef_row;   /* row # of first uninitialized row */
167  boolean pre_zero;             /* pre-zero mode requested? */
168  boolean dirty;                /* do current buffer contents need written? */
169  boolean b_s_open;             /* is backing-store data valid? */
170  jvirt_sarray_ptr next;        /* link to next virtual sarray control block */
171  backing_store_info b_s_info;  /* System-dependent control info */
172};
173
174struct jvirt_barray_control {
175  JBLOCKARRAY mem_buffer;       /* => the in-memory buffer */
176  JDIMENSION rows_in_array;     /* total virtual array height */
177  JDIMENSION blocksperrow;      /* width of array (and of memory buffer) */
178  JDIMENSION maxaccess;         /* max rows accessed by access_virt_barray */
179  JDIMENSION rows_in_mem;       /* height of memory buffer */
180  JDIMENSION rowsperchunk;      /* allocation chunk size in mem_buffer */
181  JDIMENSION cur_start_row;     /* first logical row # in the buffer */
182  JDIMENSION first_undef_row;   /* row # of first uninitialized row */
183  boolean pre_zero;             /* pre-zero mode requested? */
184  boolean dirty;                /* do current buffer contents need written? */
185  boolean b_s_open;             /* is backing-store data valid? */
186  jvirt_barray_ptr next;        /* link to next virtual barray control block */
187  backing_store_info b_s_info;  /* System-dependent control info */
188};
189
190
191#ifdef MEM_STATS                /* optional extra stuff for statistics */
192
193LOCAL(void)
194print_mem_stats (j_common_ptr cinfo, int pool_id)
195{
196  my_mem_ptr mem = (my_mem_ptr) cinfo->mem;
197  small_pool_ptr shdr_ptr;
198  large_pool_ptr lhdr_ptr;
199
200  /* Since this is only a debugging stub, we can cheat a little by using
201   * fprintf directly rather than going through the trace message code.
202   * This is helpful because message parm array can't handle longs.
203   */
204  fprintf(stderr, "Freeing pool %d, total space = %ld\n",
205          pool_id, mem->total_space_allocated);
206
207  for (lhdr_ptr = mem->large_list[pool_id]; lhdr_ptr != NULL;
208       lhdr_ptr = lhdr_ptr->hdr.next) {
209    fprintf(stderr, "  Large chunk used %ld\n",
210            (long) lhdr_ptr->hdr.bytes_used);
211  }
212
213  for (shdr_ptr = mem->small_list[pool_id]; shdr_ptr != NULL;
214       shdr_ptr = shdr_ptr->hdr.next) {
215    fprintf(stderr, "  Small chunk used %ld free %ld\n",
216            (long) shdr_ptr->hdr.bytes_used,
217            (long) shdr_ptr->hdr.bytes_left);
218  }
219}
220
221#endif /* MEM_STATS */
222
223
224LOCAL(void)
225out_of_memory (j_common_ptr cinfo, int which)
226/* Report an out-of-memory error and stop execution */
227/* If we compiled MEM_STATS support, report alloc requests before dying */
228{
229#ifdef MEM_STATS
230  cinfo->err->trace_level = 2;  /* force self_destruct to report stats */
231#endif
232  ERREXIT1(cinfo, JERR_OUT_OF_MEMORY, which);
233}
234
235
236/*
237 * Allocation of "small" objects.
238 *
239 * For these, we use pooled storage.  When a new pool must be created,
240 * we try to get enough space for the current request plus a "slop" factor,
241 * where the slop will be the amount of leftover space in the new pool.
242 * The speed vs. space tradeoff is largely determined by the slop values.
243 * A different slop value is provided for each pool class (lifetime),
244 * and we also distinguish the first pool of a class from later ones.
245 * NOTE: the values given work fairly well on both 16- and 32-bit-int
246 * machines, but may be too small if longs are 64 bits or more.
247 */
248
249static const size_t first_pool_slop[JPOOL_NUMPOOLS] =
250{
251        1600,                   /* first PERMANENT pool */
252        16000                   /* first IMAGE pool */
253};
254
255static const size_t extra_pool_slop[JPOOL_NUMPOOLS] =
256{
257        0,                      /* additional PERMANENT pools */
258        5000                    /* additional IMAGE pools */
259};
260
261#define MIN_SLOP  50            /* greater than 0 to avoid futile looping */
262
263
264METHODDEF(void *)
265alloc_small (j_common_ptr cinfo, int pool_id, size_t sizeofobject)
266/* Allocate a "small" object */
267{
268  my_mem_ptr mem = (my_mem_ptr) cinfo->mem;
269  small_pool_ptr hdr_ptr, prev_hdr_ptr;
270  char * data_ptr;
271  size_t odd_bytes, min_request, slop;
272
273  /* Check for unsatisfiable request (do now to ensure no overflow below) */
274  if (sizeofobject > (size_t) (MAX_ALLOC_CHUNK-SIZEOF(small_pool_hdr)))
275    out_of_memory(cinfo, 1);    /* request exceeds malloc's ability */
276
277  /* Round up the requested size to a multiple of SIZEOF(ALIGN_TYPE) */
278  odd_bytes = sizeofobject % SIZEOF(ALIGN_TYPE);
279  if (odd_bytes > 0)
280    sizeofobject += SIZEOF(ALIGN_TYPE) - odd_bytes;
281
282  /* See if space is available in any existing pool */
283  if (pool_id < 0 || pool_id >= JPOOL_NUMPOOLS)
284    ERREXIT1(cinfo, JERR_BAD_POOL_ID, pool_id); /* safety check */
285  prev_hdr_ptr = NULL;
286  hdr_ptr = mem->small_list[pool_id];
287  while (hdr_ptr != NULL) {
288    if (hdr_ptr->hdr.bytes_left >= sizeofobject)
289      break;                    /* found pool with enough space */
290    prev_hdr_ptr = hdr_ptr;
291    hdr_ptr = hdr_ptr->hdr.next;
292  }
293
294  /* Time to make a new pool? */
295  if (hdr_ptr == NULL) {
296    /* min_request is what we need now, slop is what will be leftover */
297    min_request = sizeofobject + SIZEOF(small_pool_hdr);
298    if (prev_hdr_ptr == NULL)   /* first pool in class? */
299      slop = first_pool_slop[pool_id];
300    else
301      slop = extra_pool_slop[pool_id];
302    /* Don't ask for more than MAX_ALLOC_CHUNK */
303    if (slop > (size_t) (MAX_ALLOC_CHUNK-min_request))
304      slop = (size_t) (MAX_ALLOC_CHUNK-min_request);
305    /* Try to get space, if fail reduce slop and try again */
306    for (;;) {
307      hdr_ptr = (small_pool_ptr) jpeg_get_small(cinfo, min_request + slop);
308      if (hdr_ptr != NULL)
309        break;
310      slop /= 2;
311      if (slop < MIN_SLOP)      /* give up when it gets real small */
312        out_of_memory(cinfo, 2); /* jpeg_get_small failed */
313    }
314    mem->total_space_allocated += min_request + slop;
315    /* Success, initialize the new pool header and add to end of list */
316    hdr_ptr->hdr.next = NULL;
317    hdr_ptr->hdr.bytes_used = 0;
318    hdr_ptr->hdr.bytes_left = sizeofobject + slop;
319    if (prev_hdr_ptr == NULL)   /* first pool in class? */
320      mem->small_list[pool_id] = hdr_ptr;
321    else
322      prev_hdr_ptr->hdr.next = hdr_ptr;
323  }
324
325  /* OK, allocate the object from the current pool */
326  data_ptr = (char *) (hdr_ptr + 1); /* point to first data byte in pool */
327  data_ptr += hdr_ptr->hdr.bytes_used; /* point to place for object */
328  hdr_ptr->hdr.bytes_used += sizeofobject;
329  hdr_ptr->hdr.bytes_left -= sizeofobject;
330
331  return (void *) data_ptr;
332}
333
334
335/*
336 * Allocation of "large" objects.
337 *
338 * The external semantics of these are the same as "small" objects,
339 * except that FAR pointers are used on 80x86.  However the pool
340 * management heuristics are quite different.  We assume that each
341 * request is large enough that it may as well be passed directly to
342 * jpeg_get_large; the pool management just links everything together
343 * so that we can free it all on demand.
344 * Note: the major use of "large" objects is in JSAMPARRAY and JBLOCKARRAY
345 * structures.  The routines that create these structures (see below)
346 * deliberately bunch rows together to ensure a large request size.
347 */
348
349METHODDEF(void FAR *)
350alloc_large (j_common_ptr cinfo, int pool_id, size_t sizeofobject)
351/* Allocate a "large" object */
352{
353  my_mem_ptr mem = (my_mem_ptr) cinfo->mem;
354  large_pool_ptr hdr_ptr;
355  size_t odd_bytes;
356
357  /* Check for unsatisfiable request (do now to ensure no overflow below) */
358  if (sizeofobject > (size_t) (MAX_ALLOC_CHUNK-SIZEOF(large_pool_hdr)))
359    out_of_memory(cinfo, 3);    /* request exceeds malloc's ability */
360
361  /* Round up the requested size to a multiple of SIZEOF(ALIGN_TYPE) */
362  odd_bytes = sizeofobject % SIZEOF(ALIGN_TYPE);
363  if (odd_bytes > 0)
364    sizeofobject += SIZEOF(ALIGN_TYPE) - odd_bytes;
365
366  /* Always make a new pool */
367  if (pool_id < 0 || pool_id >= JPOOL_NUMPOOLS)
368    ERREXIT1(cinfo, JERR_BAD_POOL_ID, pool_id); /* safety check */
369
370  hdr_ptr = (large_pool_ptr) jpeg_get_large(cinfo, sizeofobject +
371                                            SIZEOF(large_pool_hdr));
372  if (hdr_ptr == NULL)
373    out_of_memory(cinfo, 4);    /* jpeg_get_large failed */
374  mem->total_space_allocated += sizeofobject + SIZEOF(large_pool_hdr);
375
376  /* Success, initialize the new pool header and add to list */
377  hdr_ptr->hdr.next = mem->large_list[pool_id];
378  /* We maintain space counts in each pool header for statistical purposes,
379   * even though they are not needed for allocation.
380   */
381  hdr_ptr->hdr.bytes_used = sizeofobject;
382  hdr_ptr->hdr.bytes_left = 0;
383  mem->large_list[pool_id] = hdr_ptr;
384
385  return (void FAR *) (hdr_ptr + 1); /* point to first data byte in pool */
386}
387
388
389/*
390 * Creation of 2-D sample arrays.
391 * The pointers are in near heap, the samples themselves in FAR heap.
392 *
393 * To minimize allocation overhead and to allow I/O of large contiguous
394 * blocks, we allocate the sample rows in groups of as many rows as possible
395 * without exceeding MAX_ALLOC_CHUNK total bytes per allocation request.
396 * NB: the virtual array control routines, later in this file, know about
397 * this chunking of rows.  The rowsperchunk value is left in the mem manager
398 * object so that it can be saved away if this sarray is the workspace for
399 * a virtual array.
400 */
401
402METHODDEF(JSAMPARRAY)
403alloc_sarray (j_common_ptr cinfo, int pool_id,
404              JDIMENSION samplesperrow, JDIMENSION numrows)
405/* Allocate a 2-D sample array */
406{
407  my_mem_ptr mem = (my_mem_ptr) cinfo->mem;
408  JSAMPARRAY result;
409  JSAMPROW workspace;
410  JDIMENSION rowsperchunk, currow, i;
411  long ltemp;
412
413  /* Calculate max # of rows allowed in one allocation chunk */
414  ltemp = (MAX_ALLOC_CHUNK-SIZEOF(large_pool_hdr)) /
415          ((long) samplesperrow * SIZEOF(JSAMPLE));
416  if (ltemp <= 0)
417    ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);
418  if (ltemp < (long) numrows)
419    rowsperchunk = (JDIMENSION) ltemp;
420  else
421    rowsperchunk = numrows;
422  mem->last_rowsperchunk = rowsperchunk;
423
424  /* Get space for row pointers (small object) */
425  result = (JSAMPARRAY) alloc_small(cinfo, pool_id,
426                                    (size_t) (numrows * SIZEOF(JSAMPROW)));
427
428  /* Get the rows themselves (large objects) */
429  currow = 0;
430  while (currow < numrows) {
431    rowsperchunk = MIN(rowsperchunk, numrows - currow);
432    workspace = (JSAMPROW) alloc_large(cinfo, pool_id,
433        (size_t) ((size_t) rowsperchunk * (size_t) samplesperrow
434                  * SIZEOF(JSAMPLE)));
435    for (i = rowsperchunk; i > 0; i--) {
436      result[currow++] = workspace;
437      workspace += samplesperrow;
438    }
439  }
440
441  return result;
442}
443
444
445/*
446 * Creation of 2-D coefficient-block arrays.
447 * This is essentially the same as the code for sample arrays, above.
448 */
449
450METHODDEF(JBLOCKARRAY)
451alloc_barray (j_common_ptr cinfo, int pool_id,
452              JDIMENSION blocksperrow, JDIMENSION numrows)
453/* Allocate a 2-D coefficient-block array */
454{
455  my_mem_ptr mem = (my_mem_ptr) cinfo->mem;
456  JBLOCKARRAY result;
457  JBLOCKROW workspace;
458  JDIMENSION rowsperchunk, currow, i;
459  long ltemp;
460
461  /* Calculate max # of rows allowed in one allocation chunk */
462  ltemp = (MAX_ALLOC_CHUNK-SIZEOF(large_pool_hdr)) /
463          ((long) blocksperrow * SIZEOF(JBLOCK));
464  if (ltemp <= 0)
465    ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);
466  if (ltemp < (long) numrows)
467    rowsperchunk = (JDIMENSION) ltemp;
468  else
469    rowsperchunk = numrows;
470  mem->last_rowsperchunk = rowsperchunk;
471
472  /* Get space for row pointers (small object) */
473  result = (JBLOCKARRAY) alloc_small(cinfo, pool_id,
474                                     (size_t) (numrows * SIZEOF(JBLOCKROW)));
475
476  /* Get the rows themselves (large objects) */
477  currow = 0;
478  while (currow < numrows) {
479    rowsperchunk = MIN(rowsperchunk, numrows - currow);
480    workspace = (JBLOCKROW) alloc_large(cinfo, pool_id,
481        (size_t) ((size_t) rowsperchunk * (size_t) blocksperrow
482                  * SIZEOF(JBLOCK)));
483    for (i = rowsperchunk; i > 0; i--) {
484      result[currow++] = workspace;
485      workspace += blocksperrow;
486    }
487  }
488
489  return result;
490}
491
492
493/*
494 * About virtual array management:
495 *
496 * The above "normal" array routines are only used to allocate strip buffers
497 * (as wide as the image, but just a few rows high).  Full-image-sized buffers
498 * are handled as "virtual" arrays.  The array is still accessed a strip at a
499 * time, but the memory manager must save the whole array for repeated
500 * accesses.  The intended implementation is that there is a strip buffer in
501 * memory (as high as is possible given the desired memory limit), plus a
502 * backing file that holds the rest of the array.
503 *
504 * The request_virt_array routines are told the total size of the image and
505 * the maximum number of rows that will be accessed at once.  The in-memory
506 * buffer must be at least as large as the maxaccess value.
507 *
508 * The request routines create control blocks but not the in-memory buffers.
509 * That is postponed until realize_virt_arrays is called.  At that time the
510 * total amount of space needed is known (approximately, anyway), so free
511 * memory can be divided up fairly.
512 *
513 * The access_virt_array routines are responsible for making a specific strip
514 * area accessible (after reading or writing the backing file, if necessary).
515 * Note that the access routines are told whether the caller intends to modify
516 * the accessed strip; during a read-only pass this saves having to rewrite
517 * data to disk.  The access routines are also responsible for pre-zeroing
518 * any newly accessed rows, if pre-zeroing was requested.
519 *
520 * In current usage, the access requests are usually for nonoverlapping
521 * strips; that is, successive access start_row numbers differ by exactly
522 * num_rows = maxaccess.  This means we can get good performance with simple
523 * buffer dump/reload logic, by making the in-memory buffer be a multiple
524 * of the access height; then there will never be accesses across bufferload
525 * boundaries.  The code will still work with overlapping access requests,
526 * but it doesn't handle bufferload overlaps very efficiently.
527 */
528
529
530METHODDEF(jvirt_sarray_ptr)
531request_virt_sarray (j_common_ptr cinfo, int pool_id, boolean pre_zero,
532                     JDIMENSION samplesperrow, JDIMENSION numrows,
533                     JDIMENSION maxaccess)
534/* Request a virtual 2-D sample array */
535{
536  my_mem_ptr mem = (my_mem_ptr) cinfo->mem;
537  jvirt_sarray_ptr result;
538
539  /* Only IMAGE-lifetime virtual arrays are currently supported */
540  if (pool_id != JPOOL_IMAGE)
541    ERREXIT1(cinfo, JERR_BAD_POOL_ID, pool_id); /* safety check */
542
543  /* get control block */
544  result = (jvirt_sarray_ptr) alloc_small(cinfo, pool_id,
545                                          SIZEOF(struct jvirt_sarray_control));
546
547  result->mem_buffer = NULL;    /* marks array not yet realized */
548  result->rows_in_array = numrows;
549  result->samplesperrow = samplesperrow;
550  result->maxaccess = maxaccess;
551  result->pre_zero = pre_zero;
552  result->b_s_open = FALSE;     /* no associated backing-store object */
553  result->next = mem->virt_sarray_list; /* add to list of virtual arrays */
554  mem->virt_sarray_list = result;
555
556  return result;
557}
558
559
560METHODDEF(jvirt_barray_ptr)
561request_virt_barray (j_common_ptr cinfo, int pool_id, boolean pre_zero,
562                     JDIMENSION blocksperrow, JDIMENSION numrows,
563                     JDIMENSION maxaccess)
564/* Request a virtual 2-D coefficient-block array */
565{
566  my_mem_ptr mem = (my_mem_ptr) cinfo->mem;
567  jvirt_barray_ptr result;
568
569  /* Only IMAGE-lifetime virtual arrays are currently supported */
570  if (pool_id != JPOOL_IMAGE)
571    ERREXIT1(cinfo, JERR_BAD_POOL_ID, pool_id); /* safety check */
572
573  /* get control block */
574  result = (jvirt_barray_ptr) alloc_small(cinfo, pool_id,
575                                          SIZEOF(struct jvirt_barray_control));
576
577  result->mem_buffer = NULL;    /* marks array not yet realized */
578  result->rows_in_array = numrows;
579  result->blocksperrow = blocksperrow;
580  result->maxaccess = maxaccess;
581  result->pre_zero = pre_zero;
582  result->b_s_open = FALSE;     /* no associated backing-store object */
583  result->next = mem->virt_barray_list; /* add to list of virtual arrays */
584  mem->virt_barray_list = result;
585
586  return result;
587}
588
589
590METHODDEF(void)
591realize_virt_arrays (j_common_ptr cinfo)
592/* Allocate the in-memory buffers for any unrealized virtual arrays */
593{
594  my_mem_ptr mem = (my_mem_ptr) cinfo->mem;
595  long space_per_minheight, maximum_space, avail_mem;
596  long minheights, max_minheights;
597  jvirt_sarray_ptr sptr;
598  jvirt_barray_ptr bptr;
599
600  /* Compute the minimum space needed (maxaccess rows in each buffer)
601   * and the maximum space needed (full image height in each buffer).
602   * These may be of use to the system-dependent jpeg_mem_available routine.
603   */
604  space_per_minheight = 0;
605  maximum_space = 0;
606  for (sptr = mem->virt_sarray_list; sptr != NULL; sptr = sptr->next) {
607    if (sptr->mem_buffer == NULL) { /* if not realized yet */
608      space_per_minheight += (long) sptr->maxaccess *
609                             (long) sptr->samplesperrow * SIZEOF(JSAMPLE);
610      maximum_space += (long) sptr->rows_in_array *
611                       (long) sptr->samplesperrow * SIZEOF(JSAMPLE);
612    }
613  }
614  for (bptr = mem->virt_barray_list; bptr != NULL; bptr = bptr->next) {
615    if (bptr->mem_buffer == NULL) { /* if not realized yet */
616      space_per_minheight += (long) bptr->maxaccess *
617                             (long) bptr->blocksperrow * SIZEOF(JBLOCK);
618      maximum_space += (long) bptr->rows_in_array *
619                       (long) bptr->blocksperrow * SIZEOF(JBLOCK);
620    }
621  }
622
623  if (space_per_minheight <= 0)
624    return;                     /* no unrealized arrays, no work */
625
626  /* Determine amount of memory to actually use; this is system-dependent. */
627  avail_mem = jpeg_mem_available(cinfo, space_per_minheight, maximum_space,
628                                 mem->total_space_allocated);
629
630  /* If the maximum space needed is available, make all the buffers full
631   * height; otherwise parcel it out with the same number of minheights
632   * in each buffer.
633   */
634  if (avail_mem >= maximum_space)
635    max_minheights = 1000000000L;
636  else {
637    max_minheights = avail_mem / space_per_minheight;
638    /* If there doesn't seem to be enough space, try to get the minimum
639     * anyway.  This allows a "stub" implementation of jpeg_mem_available().
640     */
641    if (max_minheights <= 0)
642      max_minheights = 1;
643  }
644
645  /* Allocate the in-memory buffers and initialize backing store as needed. */
646
647  for (sptr = mem->virt_sarray_list; sptr != NULL; sptr = sptr->next) {
648    if (sptr->mem_buffer == NULL) { /* if not realized yet */
649      minheights = ((long) sptr->rows_in_array - 1L) / sptr->maxaccess + 1L;
650      if (minheights <= max_minheights) {
651        /* This buffer fits in memory */
652        sptr->rows_in_mem = sptr->rows_in_array;
653      } else {
654        /* It doesn't fit in memory, create backing store. */
655        sptr->rows_in_mem = (JDIMENSION) (max_minheights * sptr->maxaccess);
656        jpeg_open_backing_store(cinfo, & sptr->b_s_info,
657                                (long) sptr->rows_in_array *
658                                (long) sptr->samplesperrow *
659                                (long) SIZEOF(JSAMPLE));
660        sptr->b_s_open = TRUE;
661      }
662      sptr->mem_buffer = alloc_sarray(cinfo, JPOOL_IMAGE,
663                                      sptr->samplesperrow, sptr->rows_in_mem);
664      sptr->rowsperchunk = mem->last_rowsperchunk;
665      sptr->cur_start_row = 0;
666      sptr->first_undef_row = 0;
667      sptr->dirty = FALSE;
668    }
669  }
670
671  for (bptr = mem->virt_barray_list; bptr != NULL; bptr = bptr->next) {
672    if (bptr->mem_buffer == NULL) { /* if not realized yet */
673      minheights = ((long) bptr->rows_in_array - 1L) / bptr->maxaccess + 1L;
674      if (minheights <= max_minheights) {
675        /* This buffer fits in memory */
676        bptr->rows_in_mem = bptr->rows_in_array;
677      } else {
678        /* It doesn't fit in memory, create backing store. */
679        bptr->rows_in_mem = (JDIMENSION) (max_minheights * bptr->maxaccess);
680        jpeg_open_backing_store(cinfo, & bptr->b_s_info,
681                                (long) bptr->rows_in_array *
682                                (long) bptr->blocksperrow *
683                                (long) SIZEOF(JBLOCK));
684        bptr->b_s_open = TRUE;
685      }
686      bptr->mem_buffer = alloc_barray(cinfo, JPOOL_IMAGE,
687                                      bptr->blocksperrow, bptr->rows_in_mem);
688      bptr->rowsperchunk = mem->last_rowsperchunk;
689      bptr->cur_start_row = 0;
690      bptr->first_undef_row = 0;
691      bptr->dirty = FALSE;
692    }
693  }
694}
695
696
697LOCAL(void)
698do_sarray_io (j_common_ptr cinfo, jvirt_sarray_ptr ptr, boolean writing)
699/* Do backing store read or write of a virtual sample array */
700{
701  long bytesperrow, file_offset, byte_count, rows, thisrow, i;
702
703  bytesperrow = (long) ptr->samplesperrow * SIZEOF(JSAMPLE);
704  file_offset = ptr->cur_start_row * bytesperrow;
705  /* Loop to read or write each allocation chunk in mem_buffer */
706  for (i = 0; i < (long) ptr->rows_in_mem; i += ptr->rowsperchunk) {
707    /* One chunk, but check for short chunk at end of buffer */
708    rows = MIN((long) ptr->rowsperchunk, (long) ptr->rows_in_mem - i);
709    /* Transfer no more than is currently defined */
710    thisrow = (long) ptr->cur_start_row + i;
711    rows = MIN(rows, (long) ptr->first_undef_row - thisrow);
712    /* Transfer no more than fits in file */
713    rows = MIN(rows, (long) ptr->rows_in_array - thisrow);
714    if (rows <= 0)              /* this chunk might be past end of file! */
715      break;
716    byte_count = rows * bytesperrow;
717    if (writing)
718      (*ptr->b_s_info.write_backing_store) (cinfo, & ptr->b_s_info,
719                                            (void FAR *) ptr->mem_buffer[i],
720                                            file_offset, byte_count);
721    else
722      (*ptr->b_s_info.read_backing_store) (cinfo, & ptr->b_s_info,
723                                           (void FAR *) ptr->mem_buffer[i],
724                                           file_offset, byte_count);
725    file_offset += byte_count;
726  }
727}
728
729
730LOCAL(void)
731do_barray_io (j_common_ptr cinfo, jvirt_barray_ptr ptr, boolean writing)
732/* Do backing store read or write of a virtual coefficient-block array */
733{
734  long bytesperrow, file_offset, byte_count, rows, thisrow, i;
735
736  bytesperrow = (long) ptr->blocksperrow * SIZEOF(JBLOCK);
737  file_offset = ptr->cur_start_row * bytesperrow;
738  /* Loop to read or write each allocation chunk in mem_buffer */
739  for (i = 0; i < (long) ptr->rows_in_mem; i += ptr->rowsperchunk) {
740    /* One chunk, but check for short chunk at end of buffer */
741    rows = MIN((long) ptr->rowsperchunk, (long) ptr->rows_in_mem - i);
742    /* Transfer no more than is currently defined */
743    thisrow = (long) ptr->cur_start_row + i;
744    rows = MIN(rows, (long) ptr->first_undef_row - thisrow);
745    /* Transfer no more than fits in file */
746    rows = MIN(rows, (long) ptr->rows_in_array - thisrow);
747    if (rows <= 0)              /* this chunk might be past end of file! */
748      break;
749    byte_count = rows * bytesperrow;
750    if (writing)
751      (*ptr->b_s_info.write_backing_store) (cinfo, & ptr->b_s_info,
752                                            (void FAR *) ptr->mem_buffer[i],
753                                            file_offset, byte_count);
754    else
755      (*ptr->b_s_info.read_backing_store) (cinfo, & ptr->b_s_info,
756                                           (void FAR *) ptr->mem_buffer[i],
757                                           file_offset, byte_count);
758    file_offset += byte_count;
759  }
760}
761
762
763METHODDEF(JSAMPARRAY)
764access_virt_sarray (j_common_ptr cinfo, jvirt_sarray_ptr ptr,
765                    JDIMENSION start_row, JDIMENSION num_rows,
766                    boolean writable)
767/* Access the part of a virtual sample array starting at start_row */
768/* and extending for num_rows rows.  writable is true if  */
769/* caller intends to modify the accessed area. */
770{
771  JDIMENSION end_row = start_row + num_rows;
772  JDIMENSION undef_row;
773
774  /* debugging check */
775  if (end_row > ptr->rows_in_array || num_rows > ptr->maxaccess ||
776      ptr->mem_buffer == NULL)
777    ERREXIT(cinfo, JERR_BAD_VIRTUAL_ACCESS);
778
779  /* Make the desired part of the virtual array accessible */
780  if (start_row < ptr->cur_start_row ||
781      end_row > ptr->cur_start_row+ptr->rows_in_mem) {
782    if (! ptr->b_s_open)
783      ERREXIT(cinfo, JERR_VIRTUAL_BUG);
784    /* Flush old buffer contents if necessary */
785    if (ptr->dirty) {
786      do_sarray_io(cinfo, ptr, TRUE);
787      ptr->dirty = FALSE;
788    }
789    /* Decide what part of virtual array to access.
790     * Algorithm: if target address > current window, assume forward scan,
791     * load starting at target address.  If target address < current window,
792     * assume backward scan, load so that target area is top of window.
793     * Note that when switching from forward write to forward read, will have
794     * start_row = 0, so the limiting case applies and we load from 0 anyway.
795     */
796    if (start_row > ptr->cur_start_row) {
797      ptr->cur_start_row = start_row;
798    } else {
799      /* use long arithmetic here to avoid overflow & unsigned problems */
800      long ltemp;
801
802      ltemp = (long) end_row - (long) ptr->rows_in_mem;
803      if (ltemp < 0)
804        ltemp = 0;              /* don't fall off front end of file */
805      ptr->cur_start_row = (JDIMENSION) ltemp;
806    }
807    /* Read in the selected part of the array.
808     * During the initial write pass, we will do no actual read
809     * because the selected part is all undefined.
810     */
811    do_sarray_io(cinfo, ptr, FALSE);
812  }
813  /* Ensure the accessed part of the array is defined; prezero if needed.
814   * To improve locality of access, we only prezero the part of the array
815   * that the caller is about to access, not the entire in-memory array.
816   */
817  if (ptr->first_undef_row < end_row) {
818    if (ptr->first_undef_row < start_row) {
819      if (writable)             /* writer skipped over a section of array */
820        ERREXIT(cinfo, JERR_BAD_VIRTUAL_ACCESS);
821      undef_row = start_row;    /* but reader is allowed to read ahead */
822    } else {
823      undef_row = ptr->first_undef_row;
824    }
825    if (writable)
826      ptr->first_undef_row = end_row;
827    if (ptr->pre_zero) {
828      size_t bytesperrow = (size_t) ptr->samplesperrow * SIZEOF(JSAMPLE);
829      undef_row -= ptr->cur_start_row; /* make indexes relative to buffer */
830      end_row -= ptr->cur_start_row;
831      while (undef_row < end_row) {
832        jzero_far((void FAR *) ptr->mem_buffer[undef_row], bytesperrow);
833        undef_row++;
834      }
835    } else {
836      if (! writable)           /* reader looking at undefined data */
837        ERREXIT(cinfo, JERR_BAD_VIRTUAL_ACCESS);
838    }
839  }
840  /* Flag the buffer dirty if caller will write in it */
841  if (writable)
842    ptr->dirty = TRUE;
843  /* Return address of proper part of the buffer */
844  return ptr->mem_buffer + (start_row - ptr->cur_start_row);
845}
846
847
848METHODDEF(JBLOCKARRAY)
849access_virt_barray (j_common_ptr cinfo, jvirt_barray_ptr ptr,
850                    JDIMENSION start_row, JDIMENSION num_rows,
851                    boolean writable)
852/* Access the part of a virtual block array starting at start_row */
853/* and extending for num_rows rows.  writable is true if  */
854/* caller intends to modify the accessed area. */
855{
856  JDIMENSION end_row = start_row + num_rows;
857  JDIMENSION undef_row;
858
859  /* debugging check */
860  if (end_row > ptr->rows_in_array || num_rows > ptr->maxaccess ||
861      ptr->mem_buffer == NULL)
862    ERREXIT(cinfo, JERR_BAD_VIRTUAL_ACCESS);
863
864  /* Make the desired part of the virtual array accessible */
865  if (start_row < ptr->cur_start_row ||
866      end_row > ptr->cur_start_row+ptr->rows_in_mem) {
867    if (! ptr->b_s_open)
868      ERREXIT(cinfo, JERR_VIRTUAL_BUG);
869    /* Flush old buffer contents if necessary */
870    if (ptr->dirty) {
871      do_barray_io(cinfo, ptr, TRUE);
872      ptr->dirty = FALSE;
873    }
874    /* Decide what part of virtual array to access.
875     * Algorithm: if target address > current window, assume forward scan,
876     * load starting at target address.  If target address < current window,
877     * assume backward scan, load so that target area is top of window.
878     * Note that when switching from forward write to forward read, will have
879     * start_row = 0, so the limiting case applies and we load from 0 anyway.
880     */
881    if (start_row > ptr->cur_start_row) {
882      ptr->cur_start_row = start_row;
883    } else {
884      /* use long arithmetic here to avoid overflow & unsigned problems */
885      long ltemp;
886
887      ltemp = (long) end_row - (long) ptr->rows_in_mem;
888      if (ltemp < 0)
889        ltemp = 0;              /* don't fall off front end of file */
890      ptr->cur_start_row = (JDIMENSION) ltemp;
891    }
892    /* Read in the selected part of the array.
893     * During the initial write pass, we will do no actual read
894     * because the selected part is all undefined.
895     */
896    do_barray_io(cinfo, ptr, FALSE);
897  }
898  /* Ensure the accessed part of the array is defined; prezero if needed.
899   * To improve locality of access, we only prezero the part of the array
900   * that the caller is about to access, not the entire in-memory array.
901   */
902  if (ptr->first_undef_row < end_row) {
903    if (ptr->first_undef_row < start_row) {
904      if (writable)             /* writer skipped over a section of array */
905        ERREXIT(cinfo, JERR_BAD_VIRTUAL_ACCESS);
906      undef_row = start_row;    /* but reader is allowed to read ahead */
907    } else {
908      undef_row = ptr->first_undef_row;
909    }
910    if (writable)
911      ptr->first_undef_row = end_row;
912    if (ptr->pre_zero) {
913      size_t bytesperrow = (size_t) ptr->blocksperrow * SIZEOF(JBLOCK);
914      undef_row -= ptr->cur_start_row; /* make indexes relative to buffer */
915      end_row -= ptr->cur_start_row;
916      while (undef_row < end_row) {
917        jzero_far((void FAR *) ptr->mem_buffer[undef_row], bytesperrow);
918        undef_row++;
919      }
920    } else {
921      if (! writable)           /* reader looking at undefined data */
922        ERREXIT(cinfo, JERR_BAD_VIRTUAL_ACCESS);
923    }
924  }
925  /* Flag the buffer dirty if caller will write in it */
926  if (writable)
927    ptr->dirty = TRUE;
928  /* Return address of proper part of the buffer */
929  return ptr->mem_buffer + (start_row - ptr->cur_start_row);
930}
931
932
933/*
934 * Release all objects belonging to a specified pool.
935 */
936
937METHODDEF(void)
938free_pool (j_common_ptr cinfo, int pool_id)
939{
940  my_mem_ptr mem = (my_mem_ptr) cinfo->mem;
941  small_pool_ptr shdr_ptr;
942  large_pool_ptr lhdr_ptr;
943  size_t space_freed;
944
945  if (pool_id < 0 || pool_id >= JPOOL_NUMPOOLS)
946    ERREXIT1(cinfo, JERR_BAD_POOL_ID, pool_id); /* safety check */
947
948#ifdef MEM_STATS
949  if (cinfo->err->trace_level > 1)
950    print_mem_stats(cinfo, pool_id); /* print pool's memory usage statistics */
951#endif
952
953  /* If freeing IMAGE pool, close any virtual arrays first */
954  if (pool_id == JPOOL_IMAGE) {
955    jvirt_sarray_ptr sptr;
956    jvirt_barray_ptr bptr;
957
958    for (sptr = mem->virt_sarray_list; sptr != NULL; sptr = sptr->next) {
959      if (sptr->b_s_open) {     /* there may be no backing store */
960        sptr->b_s_open = FALSE; /* prevent recursive close if error */
961        (*sptr->b_s_info.close_backing_store) (cinfo, & sptr->b_s_info);
962      }
963    }
964    mem->virt_sarray_list = NULL;
965    for (bptr = mem->virt_barray_list; bptr != NULL; bptr = bptr->next) {
966      if (bptr->b_s_open) {     /* there may be no backing store */
967        bptr->b_s_open = FALSE; /* prevent recursive close if error */
968        (*bptr->b_s_info.close_backing_store) (cinfo, & bptr->b_s_info);
969      }
970    }
971    mem->virt_barray_list = NULL;
972  }
973
974  /* Release large objects */
975  lhdr_ptr = mem->large_list[pool_id];
976  mem->large_list[pool_id] = NULL;
977
978  while (lhdr_ptr != NULL) {
979    large_pool_ptr next_lhdr_ptr = lhdr_ptr->hdr.next;
980    space_freed = lhdr_ptr->hdr.bytes_used +
981                  lhdr_ptr->hdr.bytes_left +
982                  SIZEOF(large_pool_hdr);
983    jpeg_free_large(cinfo, (void FAR *) lhdr_ptr, space_freed);
984    mem->total_space_allocated -= space_freed;
985    lhdr_ptr = next_lhdr_ptr;
986  }
987
988  /* Release small objects */
989  shdr_ptr = mem->small_list[pool_id];
990  mem->small_list[pool_id] = NULL;
991
992  while (shdr_ptr != NULL) {
993    small_pool_ptr next_shdr_ptr = shdr_ptr->hdr.next;
994    space_freed = shdr_ptr->hdr.bytes_used +
995                  shdr_ptr->hdr.bytes_left +
996                  SIZEOF(small_pool_hdr);
997    jpeg_free_small(cinfo, (void *) shdr_ptr, space_freed);
998    mem->total_space_allocated -= space_freed;
999    shdr_ptr = next_shdr_ptr;
1000  }
1001}
1002
1003
1004/*
1005 * Close up shop entirely.
1006 * Note that this cannot be called unless cinfo->mem is non-NULL.
1007 */
1008
1009METHODDEF(void)
1010self_destruct (j_common_ptr cinfo)
1011{
1012  int pool;
1013
1014  /* Close all backing store, release all memory.
1015   * Releasing pools in reverse order might help avoid fragmentation
1016   * with some (brain-damaged) malloc libraries.
1017   */
1018  for (pool = JPOOL_NUMPOOLS-1; pool >= JPOOL_PERMANENT; pool--) {
1019    free_pool(cinfo, pool);
1020  }
1021
1022  /* Release the memory manager control block too. */
1023  jpeg_free_small(cinfo, (void *) cinfo->mem, SIZEOF(my_memory_mgr));
1024  cinfo->mem = NULL;            /* ensures I will be called only once */
1025
1026  jpeg_mem_term(cinfo);         /* system-dependent cleanup */
1027}
1028
1029
1030/*
1031 * Memory manager initialization.
1032 * When this is called, only the error manager pointer is valid in cinfo!
1033 */
1034
1035GLOBAL(void)
1036jinit_memory_mgr (j_common_ptr cinfo)
1037{
1038  my_mem_ptr mem;
1039  long max_to_use;
1040  int pool;
1041  size_t test_mac;
1042
1043  cinfo->mem = NULL;            /* for safety if init fails */
1044
1045  /* Check for configuration errors.
1046   * SIZEOF(ALIGN_TYPE) should be a power of 2; otherwise, it probably
1047   * doesn't reflect any real hardware alignment requirement.
1048   * The test is a little tricky: for X>0, X and X-1 have no one-bits
1049   * in common if and only if X is a power of 2, ie has only one one-bit.
1050   * Some compilers may give an "unreachable code" warning here; ignore it.
1051   */
1052  if ((SIZEOF(ALIGN_TYPE) & (SIZEOF(ALIGN_TYPE)-1)) != 0)
1053    ERREXIT(cinfo, JERR_BAD_ALIGN_TYPE);
1054  /* MAX_ALLOC_CHUNK must be representable as type size_t, and must be
1055   * a multiple of SIZEOF(ALIGN_TYPE).
1056   * Again, an "unreachable code" warning may be ignored here.
1057   * But a "constant too large" warning means you need to fix MAX_ALLOC_CHUNK.
1058   */
1059  test_mac = (size_t) MAX_ALLOC_CHUNK;
1060  if ((long) test_mac != MAX_ALLOC_CHUNK ||
1061      (MAX_ALLOC_CHUNK % SIZEOF(ALIGN_TYPE)) != 0)
1062    ERREXIT(cinfo, JERR_BAD_ALLOC_CHUNK);
1063
1064  max_to_use = jpeg_mem_init(cinfo); /* system-dependent initialization */
1065
1066  /* Attempt to allocate memory manager's control block */
1067  mem = (my_mem_ptr) jpeg_get_small(cinfo, SIZEOF(my_memory_mgr));
1068
1069  if (mem == NULL) {
1070    jpeg_mem_term(cinfo);       /* system-dependent cleanup */
1071    ERREXIT1(cinfo, JERR_OUT_OF_MEMORY, 0);
1072  }
1073
1074  /* OK, fill in the method pointers */
1075  mem->pub.alloc_small = alloc_small;
1076  mem->pub.alloc_large = alloc_large;
1077  mem->pub.alloc_sarray = alloc_sarray;
1078  mem->pub.alloc_barray = alloc_barray;
1079  mem->pub.request_virt_sarray = request_virt_sarray;
1080  mem->pub.request_virt_barray = request_virt_barray;
1081  mem->pub.realize_virt_arrays = realize_virt_arrays;
1082  mem->pub.access_virt_sarray = access_virt_sarray;
1083  mem->pub.access_virt_barray = access_virt_barray;
1084  mem->pub.free_pool = free_pool;
1085  mem->pub.self_destruct = self_destruct;
1086
1087  /* Initialize working state */
1088  mem->pub.max_memory_to_use = max_to_use;
1089
1090  for (pool = JPOOL_NUMPOOLS-1; pool >= JPOOL_PERMANENT; pool--) {
1091    mem->small_list[pool] = NULL;
1092    mem->large_list[pool] = NULL;
1093  }
1094  mem->virt_sarray_list = NULL;
1095  mem->virt_barray_list = NULL;
1096
1097  mem->total_space_allocated = SIZEOF(my_memory_mgr);
1098
1099  /* Declare ourselves open for business */
1100  cinfo->mem = & mem->pub;
1101
1102  /* Check for an environment variable JPEGMEM; if found, override the
1103   * default max_memory setting from jpeg_mem_init.  Note that the
1104   * surrounding application may again override this value.
1105   * If your system doesn't support getenv(), define NO_GETENV to disable
1106   * this feature.
1107   */
1108#ifndef NO_GETENV
1109  { char * memenv;
1110
1111    if ((memenv = getenv("JPEGMEM")) != NULL) {
1112      char ch = 'x';
1113
1114      if (sscanf(memenv, "%ld%c", &max_to_use, &ch) > 0) {
1115        if (ch == 'm' || ch == 'M')
1116          max_to_use *= 1000L;
1117        mem->pub.max_memory_to_use = max_to_use * 1000L;
1118      }
1119    }
1120  }
1121#endif
1122
1123}
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