1/*
2 * jmemmgr.c
3 *
4 * Copyright (C) 1991-1997, Thomas G. Lane.
5 * This file is part of the Independent JPEG Group's software.
6 * For conditions of distribution and use, see the accompanying README file.
7 *
8 * This file contains the JPEG system-independent memory management
9 * routines.  This code is usable across a wide variety of machines; most
10 * of the system dependencies have been isolated in a separate file.
11 * The major functions provided here are:
12 *   * pool-based allocation and freeing of memory;
13 *   * policy decisions about how to divide available memory among the
14 *     virtual arrays;
15 *   * control logic for swapping virtual arrays between main memory and
16 *     backing storage.
17 * The separate system-dependent file provides the actual backing-storage
18 * access code, and it contains the policy decision about how much total
19 * main memory to use.
20 * This file is system-dependent in the sense that some of its functions
21 * are unnecessary in some systems.  For example, if there is enough virtual
22 * memory so that backing storage will never be used, much of the virtual
23 * array control logic could be removed.  (Of course, if you have that much
24 * memory then you shouldn't care about a little bit of unused code...)
25 */
26
27#define JPEG_INTERNALS
28#define AM_MEMORY_MANAGER	/* we define jvirt_Xarray_control structs */
29#include "jinclude.h"
30#include "jpeglib.h"
31#include "jmemsys.h"		/* import the system-dependent declarations */
32
33#ifndef NO_GETENV
34#ifndef HAVE_STDLIB_H		/* <stdlib.h> should declare getenv() */
35extern char * getenv JPP((const char * name));
36#endif
37#endif
38
39
40/*
41 * Some important notes:
42 *   The allocation routines provided here must never return NULL.
43 *   They should exit to error_exit if unsuccessful.
44 *
45 *   It's not a good idea to try to merge the sarray and barray routines,
46 *   even though they are textually almost the same, because samples are
47 *   usually stored as bytes while coefficients are shorts or ints.  Thus,
48 *   in machines where byte pointers have a different representation from
49 *   word pointers, the resulting machine code could not be the same.
50 */
51
52
53/*
54 * Many machines require storage alignment: longs must start on 4-byte
55 * boundaries, doubles on 8-byte boundaries, etc.  On such machines, malloc()
56 * always returns pointers that are multiples of the worst-case alignment
57 * requirement, and we had better do so too.
58 * There isn't any really portable way to determine the worst-case alignment
59 * requirement.  This module assumes that the alignment requirement is
60 * multiples of sizeof(ALIGN_TYPE).
61 * By default, we define ALIGN_TYPE as double.  This is necessary on some
62 * workstations (where doubles really do need 8-byte alignment) and will work
63 * fine on nearly everything.  If your machine has lesser alignment needs,
64 * you can save a few bytes by making ALIGN_TYPE smaller.
65 * The only place I know of where this will NOT work is certain Macintosh
66 * 680x0 compilers that define double as a 10-byte IEEE extended float.
67 * Doing 10-byte alignment is counterproductive because longwords won't be
68 * aligned well.  Put "#define ALIGN_TYPE long" in jconfig.h if you have
69 * such a compiler.
70 */
71
72#ifndef ALIGN_TYPE		/* so can override from jconfig.h */
73#define ALIGN_TYPE  double
74#endif
75
76
77/*
78 * We allocate objects from "pools", where each pool is gotten with a single
79 * request to jpeg_get_small() or jpeg_get_large().  There is no per-object
80 * overhead within a pool, except for alignment padding.  Each pool has a
81 * header with a link to the next pool of the same class.
82 * Small and large pool headers are identical except that the latter's
83 * link pointer must be FAR on 80x86 machines.
84 * Notice that the "real" header fields are union'ed with a dummy ALIGN_TYPE
85 * field.  This forces the compiler to make SIZEOF(small_pool_hdr) a multiple
86 * of the alignment requirement of ALIGN_TYPE.
87 */
88
89typedef union small_pool_struct * small_pool_ptr;
90
91typedef union small_pool_struct {
92  struct {
93    small_pool_ptr next;	/* next in list of pools */
94    size_t bytes_used;		/* how many bytes already used within pool */
95    size_t bytes_left;		/* bytes still available in this pool */
96  } hdr;
97  ALIGN_TYPE dummy;		/* included in union to ensure alignment */
98} small_pool_hdr;
99
100typedef union large_pool_struct FAR * large_pool_ptr;
101
102typedef union large_pool_struct {
103  struct {
104    large_pool_ptr next;	/* next in list of pools */
105    size_t bytes_used;		/* how many bytes already used within pool */
106    size_t bytes_left;		/* bytes still available in this pool */
107  } hdr;
108  ALIGN_TYPE dummy;		/* included in union to ensure alignment */
109} large_pool_hdr;
110
111
112/*
113 * Here is the full definition of a memory manager object.
114 */
115
116typedef struct {
117  struct jpeg_memory_mgr pub;	/* public fields */
118
119  /* Each pool identifier (lifetime class) names a linked list of pools. */
120  small_pool_ptr small_list[JPOOL_NUMPOOLS];
121  large_pool_ptr large_list[JPOOL_NUMPOOLS];
122
123  /* Since we only have one lifetime class of virtual arrays, only one
124   * linked list is necessary (for each datatype).  Note that the virtual
125   * array control blocks being linked together are actually stored somewhere
126   * in the small-pool list.
127   */
128  jvirt_sarray_ptr virt_sarray_list;
129  jvirt_barray_ptr virt_barray_list;
130
131  /* This counts total space obtained from jpeg_get_small/large */
132  long total_space_allocated;
133
134  /* alloc_sarray and alloc_barray set this value for use by virtual
135   * array routines.
136   */
137  JDIMENSION last_rowsperchunk;	/* from most recent alloc_sarray/barray */
138} my_memory_mgr;
139
140typedef my_memory_mgr * my_mem_ptr;
141
142
143/*
144 * The control blocks for virtual arrays.
145 * Note that these blocks are allocated in the "small" pool area.
146 * System-dependent info for the associated backing store (if any) is hidden
147 * inside the backing_store_info struct.
148 */
149
150struct jvirt_sarray_control {
151  JSAMPARRAY mem_buffer;	/* => the in-memory buffer */
152  JDIMENSION rows_in_array;	/* total virtual array height */
153  JDIMENSION samplesperrow;	/* width of array (and of memory buffer) */
154  JDIMENSION maxaccess;		/* max rows accessed by access_virt_sarray */
155  JDIMENSION rows_in_mem;	/* height of memory buffer */
156  JDIMENSION rowsperchunk;	/* allocation chunk size in mem_buffer */
157  JDIMENSION cur_start_row;	/* first logical row # in the buffer */
158  JDIMENSION first_undef_row;	/* row # of first uninitialized row */
159  boolean pre_zero;		/* pre-zero mode requested? */
160  boolean dirty;		/* do current buffer contents need written? */
161  boolean b_s_open;		/* is backing-store data valid? */
162  jvirt_sarray_ptr next;	/* link to next virtual sarray control block */
163  backing_store_info b_s_info;	/* System-dependent control info */
164};
165
166struct jvirt_barray_control {
167  JBLOCKARRAY mem_buffer;	/* => the in-memory buffer */
168  JDIMENSION rows_in_array;	/* total virtual array height */
169  JDIMENSION blocksperrow;	/* width of array (and of memory buffer) */
170  JDIMENSION maxaccess;		/* max rows accessed by access_virt_barray */
171  JDIMENSION rows_in_mem;	/* height of memory buffer */
172  JDIMENSION rowsperchunk;	/* allocation chunk size in mem_buffer */
173  JDIMENSION cur_start_row;	/* first logical row # in the buffer */
174  JDIMENSION first_undef_row;	/* row # of first uninitialized row */
175  boolean pre_zero;		/* pre-zero mode requested? */
176  boolean dirty;		/* do current buffer contents need written? */
177  boolean b_s_open;		/* is backing-store data valid? */
178  jvirt_barray_ptr next;	/* link to next virtual barray control block */
179  backing_store_info b_s_info;	/* System-dependent control info */
180};
181
182
183#ifdef MEM_STATS		/* optional extra stuff for statistics */
184
185LOCAL(void)
186print_mem_stats (j_common_ptr cinfo, int pool_id)
187{
188  my_mem_ptr mem = (my_mem_ptr) cinfo->mem;
189  small_pool_ptr shdr_ptr;
190  large_pool_ptr lhdr_ptr;
191
192  /* Since this is only a debugging stub, we can cheat a little by using
193   * fprintf directly rather than going through the trace message code.
194   * This is helpful because message parm array can't handle longs.
195   */
196  fprintf(stderr, "Freeing pool %d, total space = %ld\n",
197	  pool_id, mem->total_space_allocated);
198
199  for (lhdr_ptr = mem->large_list[pool_id]; lhdr_ptr != NULL;
200       lhdr_ptr = lhdr_ptr->hdr.next) {
201    fprintf(stderr, "  Large chunk used %ld\n",
202	    (long) lhdr_ptr->hdr.bytes_used);
203  }
204
205  for (shdr_ptr = mem->small_list[pool_id]; shdr_ptr != NULL;
206       shdr_ptr = shdr_ptr->hdr.next) {
207    fprintf(stderr, "  Small chunk used %ld free %ld\n",
208	    (long) shdr_ptr->hdr.bytes_used,
209	    (long) shdr_ptr->hdr.bytes_left);
210  }
211}
212
213#endif /* MEM_STATS */
214
215
216LOCAL(void)
217out_of_memory (j_common_ptr cinfo, int which)
218/* Report an out-of-memory error and stop execution */
219/* If we compiled MEM_STATS support, report alloc requests before dying */
220{
221#ifdef MEM_STATS
222  cinfo->err->trace_level = 2;	/* force self_destruct to report stats */
223#endif
224  ERREXIT1(cinfo, JERR_OUT_OF_MEMORY, which);
225}
226
227
228/*
229 * Allocation of "small" objects.
230 *
231 * For these, we use pooled storage.  When a new pool must be created,
232 * we try to get enough space for the current request plus a "slop" factor,
233 * where the slop will be the amount of leftover space in the new pool.
234 * The speed vs. space tradeoff is largely determined by the slop values.
235 * A different slop value is provided for each pool class (lifetime),
236 * and we also distinguish the first pool of a class from later ones.
237 * NOTE: the values given work fairly well on both 16- and 32-bit-int
238 * machines, but may be too small if longs are 64 bits or more.
239 */
240
241static const size_t first_pool_slop[JPOOL_NUMPOOLS] =
242{
243	1600,			/* first PERMANENT pool */
244	16000			/* first IMAGE pool */
245};
246
247static const size_t extra_pool_slop[JPOOL_NUMPOOLS] =
248{
249	0,			/* additional PERMANENT pools */
250	5000			/* additional IMAGE pools */
251};
252
253#define MIN_SLOP  50		/* greater than 0 to avoid futile looping */
254
255
256METHODDEF(void *)
257alloc_small (j_common_ptr cinfo, int pool_id, size_t sizeofobject)
258/* Allocate a "small" object */
259{
260  my_mem_ptr mem = (my_mem_ptr) cinfo->mem;
261  small_pool_ptr hdr_ptr, prev_hdr_ptr;
262  char * data_ptr;
263  size_t odd_bytes, min_request, slop;
264
265  /* Check for unsatisfiable request (do now to ensure no overflow below) */
266  if (sizeofobject > (size_t) (MAX_ALLOC_CHUNK-SIZEOF(small_pool_hdr)))
267    out_of_memory(cinfo, 1);	/* request exceeds malloc's ability */
268
269  /* Round up the requested size to a multiple of SIZEOF(ALIGN_TYPE) */
270  odd_bytes = sizeofobject % SIZEOF(ALIGN_TYPE);
271  if (odd_bytes > 0)
272    sizeofobject += SIZEOF(ALIGN_TYPE) - odd_bytes;
273
274  /* See if space is available in any existing pool */
275  if (pool_id < 0 || pool_id >= JPOOL_NUMPOOLS)
276    ERREXIT1(cinfo, JERR_BAD_POOL_ID, pool_id);	/* safety check */
277  prev_hdr_ptr = NULL;
278  hdr_ptr = mem->small_list[pool_id];
279  while (hdr_ptr != NULL) {
280    if (hdr_ptr->hdr.bytes_left >= sizeofobject)
281      break;			/* found pool with enough space */
282    prev_hdr_ptr = hdr_ptr;
283    hdr_ptr = hdr_ptr->hdr.next;
284  }
285
286  /* Time to make a new pool? */
287  if (hdr_ptr == NULL) {
288    /* min_request is what we need now, slop is what will be leftover */
289    min_request = sizeofobject + SIZEOF(small_pool_hdr);
290    if (prev_hdr_ptr == NULL)	/* first pool in class? */
291      slop = first_pool_slop[pool_id];
292    else
293      slop = extra_pool_slop[pool_id];
294    /* Don't ask for more than MAX_ALLOC_CHUNK */
295    if (slop > (size_t) (MAX_ALLOC_CHUNK-min_request))
296      slop = (size_t) (MAX_ALLOC_CHUNK-min_request);
297    /* Try to get space, if fail reduce slop and try again */
298    for (;;) {
299      hdr_ptr = (small_pool_ptr) jpeg_get_small(cinfo, min_request + slop);
300      if (hdr_ptr != NULL)
301	break;
302      slop /= 2;
303      if (slop < MIN_SLOP)	/* give up when it gets real small */
304	out_of_memory(cinfo, 2); /* jpeg_get_small failed */
305    }
306    mem->total_space_allocated += min_request + slop;
307    /* Success, initialize the new pool header and add to end of list */
308    hdr_ptr->hdr.next = NULL;
309    hdr_ptr->hdr.bytes_used = 0;
310    hdr_ptr->hdr.bytes_left = sizeofobject + slop;
311    if (prev_hdr_ptr == NULL)	/* first pool in class? */
312      mem->small_list[pool_id] = hdr_ptr;
313    else
314      prev_hdr_ptr->hdr.next = hdr_ptr;
315  }
316
317  /* OK, allocate the object from the current pool */
318  data_ptr = (char *) (hdr_ptr + 1); /* point to first data byte in pool */
319  data_ptr += hdr_ptr->hdr.bytes_used; /* point to place for object */
320  hdr_ptr->hdr.bytes_used += sizeofobject;
321  hdr_ptr->hdr.bytes_left -= sizeofobject;
322
323  return (void *) data_ptr;
324}
325
326
327/*
328 * Allocation of "large" objects.
329 *
330 * The external semantics of these are the same as "small" objects,
331 * except that FAR pointers are used on 80x86.  However the pool
332 * management heuristics are quite different.  We assume that each
333 * request is large enough that it may as well be passed directly to
334 * jpeg_get_large; the pool management just links everything together
335 * so that we can free it all on demand.
336 * Note: the major use of "large" objects is in JSAMPARRAY and JBLOCKARRAY
337 * structures.  The routines that create these structures (see below)
338 * deliberately bunch rows together to ensure a large request size.
339 */
340
341METHODDEF(void FAR *)
342alloc_large (j_common_ptr cinfo, int pool_id, size_t sizeofobject)
343/* Allocate a "large" object */
344{
345  my_mem_ptr mem = (my_mem_ptr) cinfo->mem;
346  large_pool_ptr hdr_ptr;
347  size_t odd_bytes;
348
349  /* Check for unsatisfiable request (do now to ensure no overflow below) */
350  if (sizeofobject > (size_t) (MAX_ALLOC_CHUNK-SIZEOF(large_pool_hdr)))
351    out_of_memory(cinfo, 3);	/* request exceeds malloc's ability */
352
353  /* Round up the requested size to a multiple of SIZEOF(ALIGN_TYPE) */
354  odd_bytes = sizeofobject % SIZEOF(ALIGN_TYPE);
355  if (odd_bytes > 0)
356    sizeofobject += SIZEOF(ALIGN_TYPE) - odd_bytes;
357
358  /* Always make a new pool */
359  if (pool_id < 0 || pool_id >= JPOOL_NUMPOOLS)
360    ERREXIT1(cinfo, JERR_BAD_POOL_ID, pool_id);	/* safety check */
361
362  hdr_ptr = (large_pool_ptr) jpeg_get_large(cinfo, sizeofobject +
363					    SIZEOF(large_pool_hdr));
364  if (hdr_ptr == NULL)
365    out_of_memory(cinfo, 4);	/* jpeg_get_large failed */
366  mem->total_space_allocated += sizeofobject + SIZEOF(large_pool_hdr);
367
368  /* Success, initialize the new pool header and add to list */
369  hdr_ptr->hdr.next = mem->large_list[pool_id];
370  /* We maintain space counts in each pool header for statistical purposes,
371   * even though they are not needed for allocation.
372   */
373  hdr_ptr->hdr.bytes_used = sizeofobject;
374  hdr_ptr->hdr.bytes_left = 0;
375  mem->large_list[pool_id] = hdr_ptr;
376
377  return (void FAR *) (hdr_ptr + 1); /* point to first data byte in pool */
378}
379
380
381/*
382 * Creation of 2-D sample arrays.
383 * The pointers are in near heap, the samples themselves in FAR heap.
384 *
385 * To minimize allocation overhead and to allow I/O of large contiguous
386 * blocks, we allocate the sample rows in groups of as many rows as possible
387 * without exceeding MAX_ALLOC_CHUNK total bytes per allocation request.
388 * NB: the virtual array control routines, later in this file, know about
389 * this chunking of rows.  The rowsperchunk value is left in the mem manager
390 * object so that it can be saved away if this sarray is the workspace for
391 * a virtual array.
392 */
393
394METHODDEF(JSAMPARRAY)
395alloc_sarray (j_common_ptr cinfo, int pool_id,
396	      JDIMENSION samplesperrow, JDIMENSION numrows)
397/* Allocate a 2-D sample array */
398{
399  my_mem_ptr mem = (my_mem_ptr) cinfo->mem;
400  JSAMPARRAY result;
401  JSAMPROW workspace;
402  JDIMENSION rowsperchunk, currow, i;
403  long ltemp;
404
405  /* Calculate max # of rows allowed in one allocation chunk */
406  ltemp = (MAX_ALLOC_CHUNK-SIZEOF(large_pool_hdr)) /
407	  ((long) samplesperrow * SIZEOF(JSAMPLE));
408  if (ltemp <= 0)
409    ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);
410  if (ltemp < (long) numrows)
411    rowsperchunk = (JDIMENSION) ltemp;
412  else
413    rowsperchunk = numrows;
414  mem->last_rowsperchunk = rowsperchunk;
415
416  /* Get space for row pointers (small object) */
417  result = (JSAMPARRAY) alloc_small(cinfo, pool_id,
418				    (size_t) (numrows * SIZEOF(JSAMPROW)));
419
420  /* Get the rows themselves (large objects) */
421  currow = 0;
422  while (currow < numrows) {
423    rowsperchunk = MIN(rowsperchunk, numrows - currow);
424    workspace = (JSAMPROW) alloc_large(cinfo, pool_id,
425	(size_t) ((size_t) rowsperchunk * (size_t) samplesperrow
426		  * SIZEOF(JSAMPLE)));
427    for (i = rowsperchunk; i > 0; i--) {
428      result[currow++] = workspace;
429      workspace += samplesperrow;
430    }
431  }
432
433  return result;
434}
435
436
437/*
438 * Creation of 2-D coefficient-block arrays.
439 * This is essentially the same as the code for sample arrays, above.
440 */
441
442METHODDEF(JBLOCKARRAY)
443alloc_barray (j_common_ptr cinfo, int pool_id,
444	      JDIMENSION blocksperrow, JDIMENSION numrows)
445/* Allocate a 2-D coefficient-block array */
446{
447  my_mem_ptr mem = (my_mem_ptr) cinfo->mem;
448  JBLOCKARRAY result;
449  JBLOCKROW workspace;
450  JDIMENSION rowsperchunk, currow, i;
451  long ltemp;
452
453  /* Calculate max # of rows allowed in one allocation chunk */
454  ltemp = (MAX_ALLOC_CHUNK-SIZEOF(large_pool_hdr)) /
455	  ((long) blocksperrow * SIZEOF(JBLOCK));
456  if (ltemp <= 0)
457    ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);
458  if (ltemp < (long) numrows)
459    rowsperchunk = (JDIMENSION) ltemp;
460  else
461    rowsperchunk = numrows;
462  mem->last_rowsperchunk = rowsperchunk;
463
464  /* Get space for row pointers (small object) */
465  result = (JBLOCKARRAY) alloc_small(cinfo, pool_id,
466				     (size_t) (numrows * SIZEOF(JBLOCKROW)));
467
468  /* Get the rows themselves (large objects) */
469  currow = 0;
470  while (currow < numrows) {
471    rowsperchunk = MIN(rowsperchunk, numrows - currow);
472    workspace = (JBLOCKROW) alloc_large(cinfo, pool_id,
473	(size_t) ((size_t) rowsperchunk * (size_t) blocksperrow
474		  * SIZEOF(JBLOCK)));
475    for (i = rowsperchunk; i > 0; i--) {
476      result[currow++] = workspace;
477      workspace += blocksperrow;
478    }
479  }
480
481  return result;
482}
483
484
485/*
486 * About virtual array management:
487 *
488 * The above "normal" array routines are only used to allocate strip buffers
489 * (as wide as the image, but just a few rows high).  Full-image-sized buffers
490 * are handled as "virtual" arrays.  The array is still accessed a strip at a
491 * time, but the memory manager must save the whole array for repeated
492 * accesses.  The intended implementation is that there is a strip buffer in
493 * memory (as high as is possible given the desired memory limit), plus a
494 * backing file that holds the rest of the array.
495 *
496 * The request_virt_array routines are told the total size of the image and
497 * the maximum number of rows that will be accessed at once.  The in-memory
498 * buffer must be at least as large as the maxaccess value.
499 *
500 * The request routines create control blocks but not the in-memory buffers.
501 * That is postponed until realize_virt_arrays is called.  At that time the
502 * total amount of space needed is known (approximately, anyway), so free
503 * memory can be divided up fairly.
504 *
505 * The access_virt_array routines are responsible for making a specific strip
506 * area accessible (after reading or writing the backing file, if necessary).
507 * Note that the access routines are told whether the caller intends to modify
508 * the accessed strip; during a read-only pass this saves having to rewrite
509 * data to disk.  The access routines are also responsible for pre-zeroing
510 * any newly accessed rows, if pre-zeroing was requested.
511 *
512 * In current usage, the access requests are usually for nonoverlapping
513 * strips; that is, successive access start_row numbers differ by exactly
514 * num_rows = maxaccess.  This means we can get good performance with simple
515 * buffer dump/reload logic, by making the in-memory buffer be a multiple
516 * of the access height; then there will never be accesses across bufferload
517 * boundaries.  The code will still work with overlapping access requests,
518 * but it doesn't handle bufferload overlaps very efficiently.
519 */
520
521
522METHODDEF(jvirt_sarray_ptr)
523request_virt_sarray (j_common_ptr cinfo, int pool_id, boolean pre_zero,
524		     JDIMENSION samplesperrow, JDIMENSION numrows,
525		     JDIMENSION maxaccess)
526/* Request a virtual 2-D sample array */
527{
528  my_mem_ptr mem = (my_mem_ptr) cinfo->mem;
529  jvirt_sarray_ptr result;
530
531  /* Only IMAGE-lifetime virtual arrays are currently supported */
532  if (pool_id != JPOOL_IMAGE)
533    ERREXIT1(cinfo, JERR_BAD_POOL_ID, pool_id);	/* safety check */
534
535  /* get control block */
536  result = (jvirt_sarray_ptr) alloc_small(cinfo, pool_id,
537					  SIZEOF(struct jvirt_sarray_control));
538
539  result->mem_buffer = NULL;	/* marks array not yet realized */
540  result->rows_in_array = numrows;
541  result->samplesperrow = samplesperrow;
542  result->maxaccess = maxaccess;
543  result->pre_zero = pre_zero;
544  result->b_s_open = FALSE;	/* no associated backing-store object */
545  result->next = mem->virt_sarray_list; /* add to list of virtual arrays */
546  mem->virt_sarray_list = result;
547
548  return result;
549}
550
551
552METHODDEF(jvirt_barray_ptr)
553request_virt_barray (j_common_ptr cinfo, int pool_id, boolean pre_zero,
554		     JDIMENSION blocksperrow, JDIMENSION numrows,
555		     JDIMENSION maxaccess)
556/* Request a virtual 2-D coefficient-block array */
557{
558  my_mem_ptr mem = (my_mem_ptr) cinfo->mem;
559  jvirt_barray_ptr result;
560
561  /* Only IMAGE-lifetime virtual arrays are currently supported */
562  if (pool_id != JPOOL_IMAGE)
563    ERREXIT1(cinfo, JERR_BAD_POOL_ID, pool_id);	/* safety check */
564
565  /* get control block */
566  result = (jvirt_barray_ptr) alloc_small(cinfo, pool_id,
567					  SIZEOF(struct jvirt_barray_control));
568
569  result->mem_buffer = NULL;	/* marks array not yet realized */
570  result->rows_in_array = numrows;
571  result->blocksperrow = blocksperrow;
572  result->maxaccess = maxaccess;
573  result->pre_zero = pre_zero;
574  result->b_s_open = FALSE;	/* no associated backing-store object */
575  result->next = mem->virt_barray_list; /* add to list of virtual arrays */
576  mem->virt_barray_list = result;
577
578  return result;
579}
580
581
582METHODDEF(void)
583realize_virt_arrays (j_common_ptr cinfo)
584/* Allocate the in-memory buffers for any unrealized virtual arrays */
585{
586  my_mem_ptr mem = (my_mem_ptr) cinfo->mem;
587  long space_per_minheight, maximum_space, avail_mem;
588  long minheights, max_minheights;
589  jvirt_sarray_ptr sptr;
590  jvirt_barray_ptr bptr;
591
592  /* Compute the minimum space needed (maxaccess rows in each buffer)
593   * and the maximum space needed (full image height in each buffer).
594   * These may be of use to the system-dependent jpeg_mem_available routine.
595   */
596  space_per_minheight = 0;
597  maximum_space = 0;
598  for (sptr = mem->virt_sarray_list; sptr != NULL; sptr = sptr->next) {
599    if (sptr->mem_buffer == NULL) { /* if not realized yet */
600      space_per_minheight += (long) sptr->maxaccess *
601			     (long) sptr->samplesperrow * SIZEOF(JSAMPLE);
602      maximum_space += (long) sptr->rows_in_array *
603		       (long) sptr->samplesperrow * SIZEOF(JSAMPLE);
604    }
605  }
606  for (bptr = mem->virt_barray_list; bptr != NULL; bptr = bptr->next) {
607    if (bptr->mem_buffer == NULL) { /* if not realized yet */
608      space_per_minheight += (long) bptr->maxaccess *
609			     (long) bptr->blocksperrow * SIZEOF(JBLOCK);
610      maximum_space += (long) bptr->rows_in_array *
611		       (long) bptr->blocksperrow * SIZEOF(JBLOCK);
612    }
613  }
614
615  if (space_per_minheight <= 0)
616    return;			/* no unrealized arrays, no work */
617
618  /* Determine amount of memory to actually use; this is system-dependent. */
619  avail_mem = jpeg_mem_available(cinfo, space_per_minheight, maximum_space,
620				 mem->total_space_allocated);
621
622  /* If the maximum space needed is available, make all the buffers full
623   * height; otherwise parcel it out with the same number of minheights
624   * in each buffer.
625   */
626  if (avail_mem >= maximum_space)
627    max_minheights = 1000000000L;
628  else {
629    max_minheights = avail_mem / space_per_minheight;
630    /* If there doesn't seem to be enough space, try to get the minimum
631     * anyway.  This allows a "stub" implementation of jpeg_mem_available().
632     */
633    if (max_minheights <= 0)
634      max_minheights = 1;
635  }
636
637  /* Allocate the in-memory buffers and initialize backing store as needed. */
638
639  for (sptr = mem->virt_sarray_list; sptr != NULL; sptr = sptr->next) {
640    if (sptr->mem_buffer == NULL) { /* if not realized yet */
641      minheights = ((long) sptr->rows_in_array - 1L) / sptr->maxaccess + 1L;
642      if (minheights <= max_minheights) {
643	/* This buffer fits in memory */
644	sptr->rows_in_mem = sptr->rows_in_array;
645      } else {
646	/* It doesn't fit in memory, create backing store. */
647	sptr->rows_in_mem = (JDIMENSION) (max_minheights * sptr->maxaccess);
648	jpeg_open_backing_store(cinfo, & sptr->b_s_info,
649				(long) sptr->rows_in_array *
650				(long) sptr->samplesperrow *
651				(long) SIZEOF(JSAMPLE));
652	sptr->b_s_open = TRUE;
653      }
654      sptr->mem_buffer = alloc_sarray(cinfo, JPOOL_IMAGE,
655				      sptr->samplesperrow, sptr->rows_in_mem);
656      sptr->rowsperchunk = mem->last_rowsperchunk;
657      sptr->cur_start_row = 0;
658      sptr->first_undef_row = 0;
659      sptr->dirty = FALSE;
660    }
661  }
662
663  for (bptr = mem->virt_barray_list; bptr != NULL; bptr = bptr->next) {
664    if (bptr->mem_buffer == NULL) { /* if not realized yet */
665      minheights = ((long) bptr->rows_in_array - 1L) / bptr->maxaccess + 1L;
666      if (minheights <= max_minheights) {
667	/* This buffer fits in memory */
668	bptr->rows_in_mem = bptr->rows_in_array;
669      } else {
670	/* It doesn't fit in memory, create backing store. */
671	bptr->rows_in_mem = (JDIMENSION) (max_minheights * bptr->maxaccess);
672	jpeg_open_backing_store(cinfo, & bptr->b_s_info,
673				(long) bptr->rows_in_array *
674				(long) bptr->blocksperrow *
675				(long) SIZEOF(JBLOCK));
676	bptr->b_s_open = TRUE;
677      }
678      bptr->mem_buffer = alloc_barray(cinfo, JPOOL_IMAGE,
679				      bptr->blocksperrow, bptr->rows_in_mem);
680      bptr->rowsperchunk = mem->last_rowsperchunk;
681      bptr->cur_start_row = 0;
682      bptr->first_undef_row = 0;
683      bptr->dirty = FALSE;
684    }
685  }
686}
687
688
689LOCAL(void)
690do_sarray_io (j_common_ptr cinfo, jvirt_sarray_ptr ptr, boolean writing)
691/* Do backing store read or write of a virtual sample array */
692{
693  long bytesperrow, file_offset, byte_count, rows, thisrow, i;
694
695  bytesperrow = (long) ptr->samplesperrow * SIZEOF(JSAMPLE);
696  file_offset = ptr->cur_start_row * bytesperrow;
697  /* Loop to read or write each allocation chunk in mem_buffer */
698  for (i = 0; i < (long) ptr->rows_in_mem; i += ptr->rowsperchunk) {
699    /* One chunk, but check for short chunk at end of buffer */
700    rows = MIN((long) ptr->rowsperchunk, (long) ptr->rows_in_mem - i);
701    /* Transfer no more than is currently defined */
702    thisrow = (long) ptr->cur_start_row + i;
703    rows = MIN(rows, (long) ptr->first_undef_row - thisrow);
704    /* Transfer no more than fits in file */
705    rows = MIN(rows, (long) ptr->rows_in_array - thisrow);
706    if (rows <= 0)		/* this chunk might be past end of file! */
707      break;
708    byte_count = rows * bytesperrow;
709    if (writing)
710      (*ptr->b_s_info.write_backing_store) (cinfo, & ptr->b_s_info,
711					    (void FAR *) ptr->mem_buffer[i],
712					    file_offset, byte_count);
713    else
714      (*ptr->b_s_info.read_backing_store) (cinfo, & ptr->b_s_info,
715					   (void FAR *) ptr->mem_buffer[i],
716					   file_offset, byte_count);
717    file_offset += byte_count;
718  }
719}
720
721
722LOCAL(void)
723do_barray_io (j_common_ptr cinfo, jvirt_barray_ptr ptr, boolean writing)
724/* Do backing store read or write of a virtual coefficient-block array */
725{
726  long bytesperrow, file_offset, byte_count, rows, thisrow, i;
727
728  bytesperrow = (long) ptr->blocksperrow * SIZEOF(JBLOCK);
729  file_offset = ptr->cur_start_row * bytesperrow;
730  /* Loop to read or write each allocation chunk in mem_buffer */
731  for (i = 0; i < (long) ptr->rows_in_mem; i += ptr->rowsperchunk) {
732    /* One chunk, but check for short chunk at end of buffer */
733    rows = MIN((long) ptr->rowsperchunk, (long) ptr->rows_in_mem - i);
734    /* Transfer no more than is currently defined */
735    thisrow = (long) ptr->cur_start_row + i;
736    rows = MIN(rows, (long) ptr->first_undef_row - thisrow);
737    /* Transfer no more than fits in file */
738    rows = MIN(rows, (long) ptr->rows_in_array - thisrow);
739    if (rows <= 0)		/* this chunk might be past end of file! */
740      break;
741    byte_count = rows * bytesperrow;
742    if (writing)
743      (*ptr->b_s_info.write_backing_store) (cinfo, & ptr->b_s_info,
744					    (void FAR *) ptr->mem_buffer[i],
745					    file_offset, byte_count);
746    else
747      (*ptr->b_s_info.read_backing_store) (cinfo, & ptr->b_s_info,
748					   (void FAR *) ptr->mem_buffer[i],
749					   file_offset, byte_count);
750    file_offset += byte_count;
751  }
752}
753
754
755METHODDEF(JSAMPARRAY)
756access_virt_sarray (j_common_ptr cinfo, jvirt_sarray_ptr ptr,
757		    JDIMENSION start_row, JDIMENSION num_rows,
758		    boolean writable)
759/* Access the part of a virtual sample array starting at start_row */
760/* and extending for num_rows rows.  writable is true if  */
761/* caller intends to modify the accessed area. */
762{
763  JDIMENSION end_row = start_row + num_rows;
764  JDIMENSION undef_row;
765
766  /* debugging check */
767  if (end_row > ptr->rows_in_array || num_rows > ptr->maxaccess ||
768      ptr->mem_buffer == NULL)
769    ERREXIT(cinfo, JERR_BAD_VIRTUAL_ACCESS);
770
771  /* Make the desired part of the virtual array accessible */
772  if (start_row < ptr->cur_start_row ||
773      end_row > ptr->cur_start_row+ptr->rows_in_mem) {
774    if (! ptr->b_s_open)
775      ERREXIT(cinfo, JERR_VIRTUAL_BUG);
776    /* Flush old buffer contents if necessary */
777    if (ptr->dirty) {
778      do_sarray_io(cinfo, ptr, TRUE);
779      ptr->dirty = FALSE;
780    }
781    /* Decide what part of virtual array to access.
782     * Algorithm: if target address > current window, assume forward scan,
783     * load starting at target address.  If target address < current window,
784     * assume backward scan, load so that target area is top of window.
785     * Note that when switching from forward write to forward read, will have
786     * start_row = 0, so the limiting case applies and we load from 0 anyway.
787     */
788    if (start_row > ptr->cur_start_row) {
789      ptr->cur_start_row = start_row;
790    } else {
791      /* use long arithmetic here to avoid overflow & unsigned problems */
792      long ltemp;
793
794      ltemp = (long) end_row - (long) ptr->rows_in_mem;
795      if (ltemp < 0)
796	ltemp = 0;		/* don't fall off front end of file */
797      ptr->cur_start_row = (JDIMENSION) ltemp;
798    }
799    /* Read in the selected part of the array.
800     * During the initial write pass, we will do no actual read
801     * because the selected part is all undefined.
802     */
803    do_sarray_io(cinfo, ptr, FALSE);
804  }
805  /* Ensure the accessed part of the array is defined; prezero if needed.
806   * To improve locality of access, we only prezero the part of the array
807   * that the caller is about to access, not the entire in-memory array.
808   */
809  if (ptr->first_undef_row < end_row) {
810    if (ptr->first_undef_row < start_row) {
811      if (writable)		/* writer skipped over a section of array */
812	ERREXIT(cinfo, JERR_BAD_VIRTUAL_ACCESS);
813      undef_row = start_row;	/* but reader is allowed to read ahead */
814    } else {
815      undef_row = ptr->first_undef_row;
816    }
817    if (writable)
818      ptr->first_undef_row = end_row;
819    if (ptr->pre_zero) {
820      size_t bytesperrow = (size_t) ptr->samplesperrow * SIZEOF(JSAMPLE);
821      undef_row -= ptr->cur_start_row; /* make indexes relative to buffer */
822      end_row -= ptr->cur_start_row;
823      while (undef_row < end_row) {
824	jzero_far((void FAR *) ptr->mem_buffer[undef_row], bytesperrow);
825	undef_row++;
826      }
827    } else {
828      if (! writable)		/* reader looking at undefined data */
829	ERREXIT(cinfo, JERR_BAD_VIRTUAL_ACCESS);
830    }
831  }
832  /* Flag the buffer dirty if caller will write in it */
833  if (writable)
834    ptr->dirty = TRUE;
835  /* Return address of proper part of the buffer */
836  return ptr->mem_buffer + (start_row - ptr->cur_start_row);
837}
838
839
840METHODDEF(JBLOCKARRAY)
841access_virt_barray (j_common_ptr cinfo, jvirt_barray_ptr ptr,
842		    JDIMENSION start_row, JDIMENSION num_rows,
843		    boolean writable)
844/* Access the part of a virtual block array starting at start_row */
845/* and extending for num_rows rows.  writable is true if  */
846/* caller intends to modify the accessed area. */
847{
848  JDIMENSION end_row = start_row + num_rows;
849  JDIMENSION undef_row;
850
851  /* debugging check */
852  if (end_row > ptr->rows_in_array || num_rows > ptr->maxaccess ||
853      ptr->mem_buffer == NULL)
854    ERREXIT(cinfo, JERR_BAD_VIRTUAL_ACCESS);
855
856  /* Make the desired part of the virtual array accessible */
857  if (start_row < ptr->cur_start_row ||
858      end_row > ptr->cur_start_row+ptr->rows_in_mem) {
859    if (! ptr->b_s_open)
860      ERREXIT(cinfo, JERR_VIRTUAL_BUG);
861    /* Flush old buffer contents if necessary */
862    if (ptr->dirty) {
863      do_barray_io(cinfo, ptr, TRUE);
864      ptr->dirty = FALSE;
865    }
866    /* Decide what part of virtual array to access.
867     * Algorithm: if target address > current window, assume forward scan,
868     * load starting at target address.  If target address < current window,
869     * assume backward scan, load so that target area is top of window.
870     * Note that when switching from forward write to forward read, will have
871     * start_row = 0, so the limiting case applies and we load from 0 anyway.
872     */
873    if (start_row > ptr->cur_start_row) {
874      ptr->cur_start_row = start_row;
875    } else {
876      /* use long arithmetic here to avoid overflow & unsigned problems */
877      long ltemp;
878
879      ltemp = (long) end_row - (long) ptr->rows_in_mem;
880      if (ltemp < 0)
881	ltemp = 0;		/* don't fall off front end of file */
882      ptr->cur_start_row = (JDIMENSION) ltemp;
883    }
884    /* Read in the selected part of the array.
885     * During the initial write pass, we will do no actual read
886     * because the selected part is all undefined.
887     */
888    do_barray_io(cinfo, ptr, FALSE);
889  }
890  /* Ensure the accessed part of the array is defined; prezero if needed.
891   * To improve locality of access, we only prezero the part of the array
892   * that the caller is about to access, not the entire in-memory array.
893   */
894  if (ptr->first_undef_row < end_row) {
895    if (ptr->first_undef_row < start_row) {
896      if (writable)		/* writer skipped over a section of array */
897	ERREXIT(cinfo, JERR_BAD_VIRTUAL_ACCESS);
898      undef_row = start_row;	/* but reader is allowed to read ahead */
899    } else {
900      undef_row = ptr->first_undef_row;
901    }
902    if (writable)
903      ptr->first_undef_row = end_row;
904    if (ptr->pre_zero) {
905      size_t bytesperrow = (size_t) ptr->blocksperrow * SIZEOF(JBLOCK);
906      undef_row -= ptr->cur_start_row; /* make indexes relative to buffer */
907      end_row -= ptr->cur_start_row;
908      while (undef_row < end_row) {
909	jzero_far((void FAR *) ptr->mem_buffer[undef_row], bytesperrow);
910	undef_row++;
911      }
912    } else {
913      if (! writable)		/* reader looking at undefined data */
914	ERREXIT(cinfo, JERR_BAD_VIRTUAL_ACCESS);
915    }
916  }
917  /* Flag the buffer dirty if caller will write in it */
918  if (writable)
919    ptr->dirty = TRUE;
920  /* Return address of proper part of the buffer */
921  return ptr->mem_buffer + (start_row - ptr->cur_start_row);
922}
923
924
925/*
926 * Release all objects belonging to a specified pool.
927 */
928
929METHODDEF(void)
930free_pool (j_common_ptr cinfo, int pool_id)
931{
932  my_mem_ptr mem = (my_mem_ptr) cinfo->mem;
933  small_pool_ptr shdr_ptr;
934  large_pool_ptr lhdr_ptr;
935  size_t space_freed;
936
937  if (pool_id < 0 || pool_id >= JPOOL_NUMPOOLS)
938    ERREXIT1(cinfo, JERR_BAD_POOL_ID, pool_id);	/* safety check */
939
940#ifdef MEM_STATS
941  if (cinfo->err->trace_level > 1)
942    print_mem_stats(cinfo, pool_id); /* print pool's memory usage statistics */
943#endif
944
945  /* If freeing IMAGE pool, close any virtual arrays first */
946  if (pool_id == JPOOL_IMAGE) {
947    jvirt_sarray_ptr sptr;
948    jvirt_barray_ptr bptr;
949
950    for (sptr = mem->virt_sarray_list; sptr != NULL; sptr = sptr->next) {
951      if (sptr->b_s_open) {	/* there may be no backing store */
952	sptr->b_s_open = FALSE;	/* prevent recursive close if error */
953	(*sptr->b_s_info.close_backing_store) (cinfo, & sptr->b_s_info);
954      }
955    }
956    mem->virt_sarray_list = NULL;
957    for (bptr = mem->virt_barray_list; bptr != NULL; bptr = bptr->next) {
958      if (bptr->b_s_open) {	/* there may be no backing store */
959	bptr->b_s_open = FALSE;	/* prevent recursive close if error */
960	(*bptr->b_s_info.close_backing_store) (cinfo, & bptr->b_s_info);
961      }
962    }
963    mem->virt_barray_list = NULL;
964  }
965
966  /* Release large objects */
967  lhdr_ptr = mem->large_list[pool_id];
968  mem->large_list[pool_id] = NULL;
969
970  while (lhdr_ptr != NULL) {
971    large_pool_ptr next_lhdr_ptr = lhdr_ptr->hdr.next;
972    space_freed = lhdr_ptr->hdr.bytes_used +
973		  lhdr_ptr->hdr.bytes_left +
974		  SIZEOF(large_pool_hdr);
975    jpeg_free_large(cinfo, (void FAR *) lhdr_ptr, space_freed);
976    mem->total_space_allocated -= space_freed;
977    lhdr_ptr = next_lhdr_ptr;
978  }
979
980  /* Release small objects */
981  shdr_ptr = mem->small_list[pool_id];
982  mem->small_list[pool_id] = NULL;
983
984  while (shdr_ptr != NULL) {
985    small_pool_ptr next_shdr_ptr = shdr_ptr->hdr.next;
986    space_freed = shdr_ptr->hdr.bytes_used +
987		  shdr_ptr->hdr.bytes_left +
988		  SIZEOF(small_pool_hdr);
989    jpeg_free_small(cinfo, (void *) shdr_ptr, space_freed);
990    mem->total_space_allocated -= space_freed;
991    shdr_ptr = next_shdr_ptr;
992  }
993}
994
995
996/*
997 * Close up shop entirely.
998 * Note that this cannot be called unless cinfo->mem is non-NULL.
999 */
1000
1001METHODDEF(void)
1002self_destruct (j_common_ptr cinfo)
1003{
1004  int pool;
1005
1006  /* Close all backing store, release all memory.
1007   * Releasing pools in reverse order might help avoid fragmentation
1008   * with some (brain-damaged) malloc libraries.
1009   */
1010  for (pool = JPOOL_NUMPOOLS-1; pool >= JPOOL_PERMANENT; pool--) {
1011    free_pool(cinfo, pool);
1012  }
1013
1014  /* Release the memory manager control block too. */
1015  jpeg_free_small(cinfo, (void *) cinfo->mem, SIZEOF(my_memory_mgr));
1016  cinfo->mem = NULL;		/* ensures I will be called only once */
1017
1018  jpeg_mem_term(cinfo);		/* system-dependent cleanup */
1019}
1020
1021
1022/*
1023 * Memory manager initialization.
1024 * When this is called, only the error manager pointer is valid in cinfo!
1025 */
1026
1027GLOBAL(void)
1028jinit_memory_mgr (j_common_ptr cinfo)
1029{
1030  my_mem_ptr mem;
1031  long max_to_use;
1032  int pool;
1033  size_t test_mac;
1034
1035  cinfo->mem = NULL;		/* for safety if init fails */
1036
1037  /* Check for configuration errors.
1038   * SIZEOF(ALIGN_TYPE) should be a power of 2; otherwise, it probably
1039   * doesn't reflect any real hardware alignment requirement.
1040   * The test is a little tricky: for X>0, X and X-1 have no one-bits
1041   * in common if and only if X is a power of 2, ie has only one one-bit.
1042   * Some compilers may give an "unreachable code" warning here; ignore it.
1043   */
1044  if ((SIZEOF(ALIGN_TYPE) & (SIZEOF(ALIGN_TYPE)-1)) != 0)
1045    ERREXIT(cinfo, JERR_BAD_ALIGN_TYPE);
1046  /* MAX_ALLOC_CHUNK must be representable as type size_t, and must be
1047   * a multiple of SIZEOF(ALIGN_TYPE).
1048   * Again, an "unreachable code" warning may be ignored here.
1049   * But a "constant too large" warning means you need to fix MAX_ALLOC_CHUNK.
1050   */
1051  test_mac = (size_t) MAX_ALLOC_CHUNK;
1052  if ((long) test_mac != MAX_ALLOC_CHUNK ||
1053      (MAX_ALLOC_CHUNK % SIZEOF(ALIGN_TYPE)) != 0)
1054    ERREXIT(cinfo, JERR_BAD_ALLOC_CHUNK);
1055
1056  max_to_use = jpeg_mem_init(cinfo); /* system-dependent initialization */
1057
1058  /* Attempt to allocate memory manager's control block */
1059  mem = (my_mem_ptr) jpeg_get_small(cinfo, SIZEOF(my_memory_mgr));
1060
1061  if (mem == NULL) {
1062    jpeg_mem_term(cinfo);	/* system-dependent cleanup */
1063    ERREXIT1(cinfo, JERR_OUT_OF_MEMORY, 0);
1064  }
1065
1066  /* OK, fill in the method pointers */
1067  mem->pub.alloc_small = alloc_small;
1068  mem->pub.alloc_large = alloc_large;
1069  mem->pub.alloc_sarray = alloc_sarray;
1070  mem->pub.alloc_barray = alloc_barray;
1071  mem->pub.request_virt_sarray = request_virt_sarray;
1072  mem->pub.request_virt_barray = request_virt_barray;
1073  mem->pub.realize_virt_arrays = realize_virt_arrays;
1074  mem->pub.access_virt_sarray = access_virt_sarray;
1075  mem->pub.access_virt_barray = access_virt_barray;
1076  mem->pub.free_pool = free_pool;
1077  mem->pub.self_destruct = self_destruct;
1078
1079  /* Make MAX_ALLOC_CHUNK accessible to other modules */
1080  mem->pub.max_alloc_chunk = MAX_ALLOC_CHUNK;
1081
1082  /* Initialize working state */
1083  mem->pub.max_memory_to_use = max_to_use;
1084
1085  for (pool = JPOOL_NUMPOOLS-1; pool >= JPOOL_PERMANENT; pool--) {
1086    mem->small_list[pool] = NULL;
1087    mem->large_list[pool] = NULL;
1088  }
1089  mem->virt_sarray_list = NULL;
1090  mem->virt_barray_list = NULL;
1091
1092  mem->total_space_allocated = SIZEOF(my_memory_mgr);
1093
1094  /* Declare ourselves open for business */
1095  cinfo->mem = & mem->pub;
1096
1097  /* Check for an environment variable JPEGMEM; if found, override the
1098   * default max_memory setting from jpeg_mem_init.  Note that the
1099   * surrounding application may again override this value.
1100   * If your system doesn't support getenv(), define NO_GETENV to disable
1101   * this feature.
1102   */
1103#ifndef NO_GETENV
1104  { char * memenv;
1105
1106    if ((memenv = getenv("JPEGMEM")) != NULL) {
1107      char ch = 'x';
1108
1109      if (sscanf(memenv, "%ld%c", &max_to_use, &ch) > 0) {
1110	if (ch == 'm' || ch == 'M')
1111	  max_to_use *= 1000L;
1112	mem->pub.max_memory_to_use = max_to_use * 1000L;
1113      }
1114    }
1115  }
1116#endif
1117
1118}
1119