1 /*
   2  * jmemmgr.c
   3  *
   4  * Copyright (C) 1991-1997, Thomas G. Lane.
   5  * Modified 2011-2012 by Guido Vollbeding.
   6  * This file is part of the Independent JPEG Group's software.
   7  * For conditions of distribution and use, see the accompanying README file.
   8  *
   9  * This file contains the JPEG system-independent memory management
  10  * routines.  This code is usable across a wide variety of machines; most
  11  * of the system dependencies have been isolated in a separate file.
  12  * The major functions provided here are:
  13  *   * pool-based allocation and freeing of memory;
  14  *   * policy decisions about how to divide available memory among the
  15  *     virtual arrays;
  16  *   * control logic for swapping virtual arrays between main memory and
  17  *     backing storage.
  18  * The separate system-dependent file provides the actual backing-storage
  19  * access code, and it contains the policy decision about how much total
  20  * main memory to use.
  21  * This file is system-dependent in the sense that some of its functions
  22  * are unnecessary in some systems.  For example, if there is enough virtual
  23  * memory so that backing storage will never be used, much of the virtual
  24  * array control logic could be removed.  (Of course, if you have that much
  25  * memory then you shouldn't care about a little bit of unused code...)
  26  */
  27 
  28 #define JPEG_INTERNALS
  29 #define AM_MEMORY_MANAGER       /* we define jvirt_Xarray_control structs */
  30 #include "jinclude.h"
  31 #include "jpeglib.h"
  32 #include "jmemsys.h"            /* import the system-dependent declarations */
  33 
  34 #ifndef NO_GETENV
  35 #ifndef HAVE_STDLIB_H           /* <stdlib.h> should declare getenv() */
  36 extern char * getenv JPP((const char * name));
  37 #endif
  38 #endif
  39 
  40 
  41 /*
  42  * Some important notes:
  43  *   The allocation routines provided here must never return NULL.
  44  *   They should exit to error_exit if unsuccessful.
  45  *
  46  *   It's not a good idea to try to merge the sarray and barray routines,
  47  *   even though they are textually almost the same, because samples are
  48  *   usually stored as bytes while coefficients are shorts or ints.  Thus,
  49  *   in machines where byte pointers have a different representation from
  50  *   word pointers, the resulting machine code could not be the same.
  51  */
  52 
  53 
  54 /*
  55  * Many machines require storage alignment: longs must start on 4-byte
  56  * boundaries, doubles on 8-byte boundaries, etc.  On such machines, malloc()
  57  * always returns pointers that are multiples of the worst-case alignment
  58  * requirement, and we had better do so too.
  59  * There isn't any really portable way to determine the worst-case alignment
  60  * requirement.  This module assumes that the alignment requirement is
  61  * multiples of sizeof(ALIGN_TYPE).
  62  * By default, we define ALIGN_TYPE as double.  This is necessary on some
  63  * workstations (where doubles really do need 8-byte alignment) and will work
  64  * fine on nearly everything.  If your machine has lesser alignment needs,
  65  * you can save a few bytes by making ALIGN_TYPE smaller.
  66  * The only place I know of where this will NOT work is certain Macintosh
  67  * 680x0 compilers that define double as a 10-byte IEEE extended float.
  68  * Doing 10-byte alignment is counterproductive because longwords won't be
  69  * aligned well.  Put "#define ALIGN_TYPE long" in jconfig.h if you have
  70  * such a compiler.
  71  */
  72 
  73 #ifndef ALIGN_TYPE              /* so can override from jconfig.h */
  74 #define ALIGN_TYPE  double
  75 #endif
  76 
  77 
  78 /*
  79  * We allocate objects from "pools", where each pool is gotten with a single
  80  * request to jpeg_get_small() or jpeg_get_large().  There is no per-object
  81  * overhead within a pool, except for alignment padding.  Each pool has a
  82  * header with a link to the next pool of the same class.
  83  * Small and large pool headers are identical except that the latter's
  84  * link pointer must be FAR on 80x86 machines.
  85  * Notice that the "real" header fields are union'ed with a dummy ALIGN_TYPE
  86  * field.  This forces the compiler to make SIZEOF(small_pool_hdr) a multiple
  87  * of the alignment requirement of ALIGN_TYPE.
  88  */
  89 
  90 typedef union small_pool_struct * small_pool_ptr;
  91 
  92 typedef union small_pool_struct {
  93   struct {
  94     small_pool_ptr next;        /* next in list of pools */
  95     size_t bytes_used;          /* how many bytes already used within pool */
  96     size_t bytes_left;          /* bytes still available in this pool */
  97   } hdr;
  98   ALIGN_TYPE dummy;             /* included in union to ensure alignment */
  99 } small_pool_hdr;
 100 
 101 typedef union large_pool_struct FAR * large_pool_ptr;
 102 
 103 typedef union large_pool_struct {
 104   struct {
 105     large_pool_ptr next;        /* next in list of pools */
 106     size_t bytes_used;          /* how many bytes already used within pool */
 107     size_t bytes_left;          /* bytes still available in this pool */
 108   } hdr;
 109   ALIGN_TYPE dummy;             /* included in union to ensure alignment */
 110 } large_pool_hdr;
 111 
 112 
 113 /*
 114  * Here is the full definition of a memory manager object.
 115  */
 116 
 117 typedef struct {
 118   struct jpeg_memory_mgr pub;   /* public fields */
 119 
 120   /* Each pool identifier (lifetime class) names a linked list of pools. */
 121   small_pool_ptr small_list[JPOOL_NUMPOOLS];
 122   large_pool_ptr large_list[JPOOL_NUMPOOLS];
 123 
 124   /* Since we only have one lifetime class of virtual arrays, only one
 125    * linked list is necessary (for each datatype).  Note that the virtual
 126    * array control blocks being linked together are actually stored somewhere
 127    * in the small-pool list.
 128    */
 129   jvirt_sarray_ptr virt_sarray_list;
 130   jvirt_barray_ptr virt_barray_list;
 131 
 132   /* This counts total space obtained from jpeg_get_small/large */
 133   long total_space_allocated;
 134 
 135   /* alloc_sarray and alloc_barray set this value for use by virtual
 136    * array routines.
 137    */
 138   JDIMENSION last_rowsperchunk; /* from most recent alloc_sarray/barray */
 139 } my_memory_mgr;
 140 
 141 typedef my_memory_mgr * my_mem_ptr;
 142 
 143 
 144 /*
 145  * The control blocks for virtual arrays.
 146  * Note that these blocks are allocated in the "small" pool area.
 147  * System-dependent info for the associated backing store (if any) is hidden
 148  * inside the backing_store_info struct.
 149  */
 150 
 151 struct jvirt_sarray_control {
 152   JSAMPARRAY mem_buffer;        /* => the in-memory buffer */
 153   JDIMENSION rows_in_array;     /* total virtual array height */
 154   JDIMENSION samplesperrow;     /* width of array (and of memory buffer) */
 155   JDIMENSION maxaccess;         /* max rows accessed by access_virt_sarray */
 156   JDIMENSION rows_in_mem;       /* height of memory buffer */
 157   JDIMENSION rowsperchunk;      /* allocation chunk size in mem_buffer */
 158   JDIMENSION cur_start_row;     /* first logical row # in the buffer */
 159   JDIMENSION first_undef_row;   /* row # of first uninitialized row */
 160   boolean pre_zero;             /* pre-zero mode requested? */
 161   boolean dirty;                /* do current buffer contents need written? */
 162   boolean b_s_open;             /* is backing-store data valid? */
 163   jvirt_sarray_ptr next;        /* link to next virtual sarray control block */
 164   backing_store_info b_s_info;  /* System-dependent control info */
 165 };
 166 
 167 struct jvirt_barray_control {
 168   JBLOCKARRAY mem_buffer;       /* => the in-memory buffer */
 169   JDIMENSION rows_in_array;     /* total virtual array height */
 170   JDIMENSION blocksperrow;      /* width of array (and of memory buffer) */
 171   JDIMENSION maxaccess;         /* max rows accessed by access_virt_barray */
 172   JDIMENSION rows_in_mem;       /* height of memory buffer */
 173   JDIMENSION rowsperchunk;      /* allocation chunk size in mem_buffer */
 174   JDIMENSION cur_start_row;     /* first logical row # in the buffer */
 175   JDIMENSION first_undef_row;   /* row # of first uninitialized row */
 176   boolean pre_zero;             /* pre-zero mode requested? */
 177   boolean dirty;                /* do current buffer contents need written? */
 178   boolean b_s_open;             /* is backing-store data valid? */
 179   jvirt_barray_ptr next;        /* link to next virtual barray control block */
 180   backing_store_info b_s_info;  /* System-dependent control info */
 181 };
 182 
 183 
 184 #ifdef MEM_STATS                /* optional extra stuff for statistics */
 185 
 186 LOCAL(void)
 187 print_mem_stats (j_common_ptr cinfo, int pool_id)
 188 {
 189   my_mem_ptr mem = (my_mem_ptr) cinfo->mem;
 190   small_pool_ptr shdr_ptr;
 191   large_pool_ptr lhdr_ptr;
 192 
 193   /* Since this is only a debugging stub, we can cheat a little by using
 194    * fprintf directly rather than going through the trace message code.
 195    * This is helpful because message parm array can't handle longs.
 196    */
 197   fprintf(stderr, "Freeing pool %d, total space = %ld\n",
 198           pool_id, mem->total_space_allocated);
 199 
 200   for (lhdr_ptr = mem->large_list[pool_id]; lhdr_ptr != NULL;
 201        lhdr_ptr = lhdr_ptr->hdr.next) {
 202     fprintf(stderr, "  Large chunk used %ld\n",
 203             (long) lhdr_ptr->hdr.bytes_used);
 204   }
 205 
 206   for (shdr_ptr = mem->small_list[pool_id]; shdr_ptr != NULL;
 207        shdr_ptr = shdr_ptr->hdr.next) {
 208     fprintf(stderr, "  Small chunk used %ld free %ld\n",
 209             (long) shdr_ptr->hdr.bytes_used,
 210             (long) shdr_ptr->hdr.bytes_left);
 211   }
 212 }
 213 
 214 #endif /* MEM_STATS */
 215 
 216 
 217 LOCAL(noreturn_t)
 218 out_of_memory (j_common_ptr cinfo, int which)
 219 /* Report an out-of-memory error and stop execution */
 220 /* If we compiled MEM_STATS support, report alloc requests before dying */
 221 {
 222 #ifdef MEM_STATS
 223   cinfo->err->trace_level = 2;    /* force self_destruct to report stats */
 224 #endif
 225   ERREXIT1(cinfo, JERR_OUT_OF_MEMORY, which);
 226 }
 227 
 228 
 229 /*
 230  * Allocation of "small" objects.
 231  *
 232  * For these, we use pooled storage.  When a new pool must be created,
 233  * we try to get enough space for the current request plus a "slop" factor,
 234  * where the slop will be the amount of leftover space in the new pool.
 235  * The speed vs. space tradeoff is largely determined by the slop values.
 236  * A different slop value is provided for each pool class (lifetime),
 237  * and we also distinguish the first pool of a class from later ones.
 238  * NOTE: the values given work fairly well on both 16- and 32-bit-int
 239  * machines, but may be too small if longs are 64 bits or more.
 240  */
 241 
 242 static const size_t first_pool_slop[JPOOL_NUMPOOLS] = 
 243 {
 244         1600,                   /* first PERMANENT pool */
 245         16000                   /* first IMAGE pool */
 246 };
 247 
 248 static const size_t extra_pool_slop[JPOOL_NUMPOOLS] = 
 249 {
 250         0,                      /* additional PERMANENT pools */
 251         5000                    /* additional IMAGE pools */
 252 };
 253 
 254 #define MIN_SLOP  50            /* greater than 0 to avoid futile looping */
 255 
 256 
 257 METHODDEF(void *)
 258 alloc_small (j_common_ptr cinfo, int pool_id, size_t sizeofobject)
 259 /* Allocate a "small" object */
 260 {
 261   my_mem_ptr mem = (my_mem_ptr) cinfo->mem;
 262   small_pool_ptr hdr_ptr, prev_hdr_ptr;
 263   char * data_ptr;
 264   size_t odd_bytes, min_request, slop;
 265 
 266   /* Check for unsatisfiable request (do now to ensure no overflow below) */
 267   if (sizeofobject > (size_t) (MAX_ALLOC_CHUNK-SIZEOF(small_pool_hdr)))
 268     out_of_memory(cinfo, 1);    /* request exceeds malloc's ability */
 269 
 270   /* Round up the requested size to a multiple of SIZEOF(ALIGN_TYPE) */
 271   odd_bytes = sizeofobject % SIZEOF(ALIGN_TYPE);
 272   if (odd_bytes > 0)
 273     sizeofobject += SIZEOF(ALIGN_TYPE) - odd_bytes;
 274 
 275   /* See if space is available in any existing pool */
 276   if (pool_id < 0 || pool_id >= JPOOL_NUMPOOLS)
 277     ERREXIT1(cinfo, JERR_BAD_POOL_ID, pool_id); /* safety check */
 278   prev_hdr_ptr = NULL;
 279   hdr_ptr = mem->small_list[pool_id];
 280   while (hdr_ptr != NULL) {
 281     if (hdr_ptr->hdr.bytes_left >= sizeofobject)
 282       break;                    /* found pool with enough space */
 283     prev_hdr_ptr = hdr_ptr;
 284     hdr_ptr = hdr_ptr->hdr.next;
 285   }
 286 
 287   /* Time to make a new pool? */
 288   if (hdr_ptr == NULL) {
 289     /* min_request is what we need now, slop is what will be leftover */
 290     min_request = sizeofobject + SIZEOF(small_pool_hdr);
 291     if (prev_hdr_ptr == NULL)   /* first pool in class? */
 292       slop = first_pool_slop[pool_id];
 293     else
 294       slop = extra_pool_slop[pool_id];
 295     /* Don't ask for more than MAX_ALLOC_CHUNK */
 296     if (slop > (size_t) (MAX_ALLOC_CHUNK-min_request))
 297       slop = (size_t) (MAX_ALLOC_CHUNK-min_request);
 298     /* Try to get space, if fail reduce slop and try again */
 299     for (;;) {
 300       hdr_ptr = (small_pool_ptr) jpeg_get_small(cinfo, min_request + slop);
 301       if (hdr_ptr != NULL)
 302         break;
 303       slop /= 2;
 304       if (slop < MIN_SLOP)   /* give up when it gets real small */
 305         out_of_memory(cinfo, 2); /* jpeg_get_small failed */
 306     }
 307     mem->total_space_allocated += min_request + slop;
 308     /* Success, initialize the new pool header and add to end of list */
 309     hdr_ptr->hdr.next = NULL;
 310     hdr_ptr->hdr.bytes_used = 0;
 311     hdr_ptr->hdr.bytes_left = sizeofobject + slop;
 312     if (prev_hdr_ptr == NULL)   /* first pool in class? */
 313       mem->small_list[pool_id] = hdr_ptr;
 314     else
 315       prev_hdr_ptr->hdr.next = hdr_ptr;
 316   }
 317 
 318   /* OK, allocate the object from the current pool */
 319   data_ptr = (char *) (hdr_ptr + 1); /* point to first data byte in pool */
 320   data_ptr += hdr_ptr->hdr.bytes_used; /* point to place for object */
 321   hdr_ptr->hdr.bytes_used += sizeofobject;
 322   hdr_ptr->hdr.bytes_left -= sizeofobject;
 323 
 324   return (void *) data_ptr;
 325 }
 326 
 327 
 328 /*
 329  * Allocation of "large" objects.
 330  *
 331  * The external semantics of these are the same as "small" objects,
 332  * except that FAR pointers are used on 80x86.  However the pool
 333  * management heuristics are quite different.  We assume that each
 334  * request is large enough that it may as well be passed directly to
 335  * jpeg_get_large; the pool management just links everything together
 336  * so that we can free it all on demand.
 337  * Note: the major use of "large" objects is in JSAMPARRAY and JBLOCKARRAY
 338  * structures.  The routines that create these structures (see below)
 339  * deliberately bunch rows together to ensure a large request size.
 340  */
 341 
 342 METHODDEF(void FAR *)
 343 alloc_large (j_common_ptr cinfo, int pool_id, size_t sizeofobject)
 344 /* Allocate a "large" object */
 345 {
 346   my_mem_ptr mem = (my_mem_ptr) cinfo->mem;
 347   large_pool_ptr hdr_ptr;
 348   size_t odd_bytes;
 349 
 350   /* Check for unsatisfiable request (do now to ensure no overflow below) */
 351   if (sizeofobject > (size_t) (MAX_ALLOC_CHUNK-SIZEOF(large_pool_hdr)))
 352     out_of_memory(cinfo, 3);    /* request exceeds malloc's ability */
 353 
 354   /* Round up the requested size to a multiple of SIZEOF(ALIGN_TYPE) */
 355   odd_bytes = sizeofobject % SIZEOF(ALIGN_TYPE);
 356   if (odd_bytes > 0)
 357     sizeofobject += SIZEOF(ALIGN_TYPE) - odd_bytes;
 358 
 359   /* Always make a new pool */
 360   if (pool_id < 0 || pool_id >= JPOOL_NUMPOOLS)
 361     ERREXIT1(cinfo, JERR_BAD_POOL_ID, pool_id); /* safety check */
 362 
 363   hdr_ptr = (large_pool_ptr) jpeg_get_large(cinfo, sizeofobject +
 364                                             SIZEOF(large_pool_hdr));
 365   if (hdr_ptr == NULL)
 366     out_of_memory(cinfo, 4);    /* jpeg_get_large failed */
 367   mem->total_space_allocated += sizeofobject + SIZEOF(large_pool_hdr);
 368 
 369   /* Success, initialize the new pool header and add to list */
 370   hdr_ptr->hdr.next = mem->large_list[pool_id];
 371   /* We maintain space counts in each pool header for statistical purposes,
 372    * even though they are not needed for allocation.
 373    */
 374   hdr_ptr->hdr.bytes_used = sizeofobject;
 375   hdr_ptr->hdr.bytes_left = 0;
 376   mem->large_list[pool_id] = hdr_ptr;
 377 
 378   return (void FAR *) (hdr_ptr + 1); /* point to first data byte in pool */
 379 }
 380 
 381 
 382 /*
 383  * Creation of 2-D sample arrays.
 384  * The pointers are in near heap, the samples themselves in FAR heap.
 385  *
 386  * To minimize allocation overhead and to allow I/O of large contiguous
 387  * blocks, we allocate the sample rows in groups of as many rows as possible
 388  * without exceeding MAX_ALLOC_CHUNK total bytes per allocation request.
 389  * NB: the virtual array control routines, later in this file, know about
 390  * this chunking of rows.  The rowsperchunk value is left in the mem manager
 391  * object so that it can be saved away if this sarray is the workspace for
 392  * a virtual array.
 393  */
 394 
 395 METHODDEF(JSAMPARRAY)
 396 alloc_sarray (j_common_ptr cinfo, int pool_id,
 397               JDIMENSION samplesperrow, JDIMENSION numrows)
 398 /* Allocate a 2-D sample array */
 399 {
 400   my_mem_ptr mem = (my_mem_ptr) cinfo->mem;
 401   JSAMPARRAY result;
 402   JSAMPROW workspace;
 403   JDIMENSION rowsperchunk, currow, i;
 404   long ltemp;
 405 
 406   /* Calculate max # of rows allowed in one allocation chunk */
 407   ltemp = (MAX_ALLOC_CHUNK-SIZEOF(large_pool_hdr)) /
 408           ((long) samplesperrow * SIZEOF(JSAMPLE));
 409   if (ltemp <= 0)
 410     ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);
 411   if (ltemp < (long) numrows)
 412     rowsperchunk = (JDIMENSION) ltemp;
 413   else
 414     rowsperchunk = numrows;
 415   mem->last_rowsperchunk = rowsperchunk;
 416 
 417   /* Get space for row pointers (small object) */
 418   result = (JSAMPARRAY) alloc_small(cinfo, pool_id,
 419                                     (size_t) (numrows * SIZEOF(JSAMPROW)));
 420 
 421   /* Get the rows themselves (large objects) */
 422   currow = 0;
 423   while (currow < numrows) {
 424     rowsperchunk = MIN(rowsperchunk, numrows - currow);
 425     workspace = (JSAMPROW) alloc_large(cinfo, pool_id,
 426         (size_t) ((size_t) rowsperchunk * (size_t) samplesperrow
 427                   * SIZEOF(JSAMPLE)));
 428     for (i = rowsperchunk; i > 0; i--) {
 429       result[currow++] = workspace;
 430       workspace += samplesperrow;
 431     }
 432   }
 433 
 434   return result;
 435 }
 436 
 437 
 438 /*
 439  * Creation of 2-D coefficient-block arrays.
 440  * This is essentially the same as the code for sample arrays, above.
 441  */
 442 
 443 METHODDEF(JBLOCKARRAY)
 444 alloc_barray (j_common_ptr cinfo, int pool_id,
 445               JDIMENSION blocksperrow, JDIMENSION numrows)
 446 /* Allocate a 2-D coefficient-block array */
 447 {
 448   my_mem_ptr mem = (my_mem_ptr) cinfo->mem;
 449   JBLOCKARRAY result;
 450   JBLOCKROW workspace;
 451   JDIMENSION rowsperchunk, currow, i;
 452   long ltemp;
 453 
 454   /* Calculate max # of rows allowed in one allocation chunk */
 455   ltemp = (MAX_ALLOC_CHUNK-SIZEOF(large_pool_hdr)) /
 456           ((long) blocksperrow * SIZEOF(JBLOCK));
 457   if (ltemp <= 0)
 458     ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);
 459   if (ltemp < (long) numrows)
 460     rowsperchunk = (JDIMENSION) ltemp;
 461   else
 462     rowsperchunk = numrows;
 463   mem->last_rowsperchunk = rowsperchunk;
 464 
 465   /* Get space for row pointers (small object) */
 466   result = (JBLOCKARRAY) alloc_small(cinfo, pool_id,
 467                                      (size_t) (numrows * SIZEOF(JBLOCKROW)));
 468 
 469   /* Get the rows themselves (large objects) */
 470   currow = 0;
 471   while (currow < numrows) {
 472     rowsperchunk = MIN(rowsperchunk, numrows - currow);
 473     workspace = (JBLOCKROW) alloc_large(cinfo, pool_id,
 474         (size_t) ((size_t) rowsperchunk * (size_t) blocksperrow
 475                   * SIZEOF(JBLOCK)));
 476     for (i = rowsperchunk; i > 0; i--) {
 477       result[currow++] = workspace;
 478       workspace += blocksperrow;
 479     }
 480   }
 481 
 482   return result;
 483 }
 484 
 485 
 486 /*
 487  * About virtual array management:
 488  *
 489  * The above "normal" array routines are only used to allocate strip buffers
 490  * (as wide as the image, but just a few rows high).  Full-image-sized buffers
 491  * are handled as "virtual" arrays.  The array is still accessed a strip at a
 492  * time, but the memory manager must save the whole array for repeated
 493  * accesses.  The intended implementation is that there is a strip buffer in
 494  * memory (as high as is possible given the desired memory limit), plus a
 495  * backing file that holds the rest of the array.
 496  *
 497  * The request_virt_array routines are told the total size of the image and
 498  * the maximum number of rows that will be accessed at once.  The in-memory
 499  * buffer must be at least as large as the maxaccess value.
 500  *
 501  * The request routines create control blocks but not the in-memory buffers.
 502  * That is postponed until realize_virt_arrays is called.  At that time the
 503  * total amount of space needed is known (approximately, anyway), so free
 504  * memory can be divided up fairly.
 505  *
 506  * The access_virt_array routines are responsible for making a specific strip
 507  * area accessible (after reading or writing the backing file, if necessary).
 508  * Note that the access routines are told whether the caller intends to modify
 509  * the accessed strip; during a read-only pass this saves having to rewrite
 510  * data to disk.  The access routines are also responsible for pre-zeroing
 511  * any newly accessed rows, if pre-zeroing was requested.
 512  *
 513  * In current usage, the access requests are usually for nonoverlapping
 514  * strips; that is, successive access start_row numbers differ by exactly
 515  * num_rows = maxaccess.  This means we can get good performance with simple
 516  * buffer dump/reload logic, by making the in-memory buffer be a multiple
 517  * of the access height; then there will never be accesses across bufferload
 518  * boundaries.  The code will still work with overlapping access requests,
 519  * but it doesn't handle bufferload overlaps very efficiently.
 520  */
 521 
 522 
 523 METHODDEF(jvirt_sarray_ptr)
 524 request_virt_sarray (j_common_ptr cinfo, int pool_id, boolean pre_zero,
 525                      JDIMENSION samplesperrow, JDIMENSION numrows,
 526                      JDIMENSION maxaccess)
 527 /* Request a virtual 2-D sample array */
 528 {
 529   my_mem_ptr mem = (my_mem_ptr) cinfo->mem;
 530   jvirt_sarray_ptr result;
 531 
 532   /* Only IMAGE-lifetime virtual arrays are currently supported */
 533   if (pool_id != JPOOL_IMAGE)
 534     ERREXIT1(cinfo, JERR_BAD_POOL_ID, pool_id); /* safety check */
 535 
 536   /* get control block */
 537   result = (jvirt_sarray_ptr) alloc_small(cinfo, pool_id,
 538                                           SIZEOF(struct jvirt_sarray_control));
 539 
 540   result->mem_buffer = NULL; /* marks array not yet realized */
 541   result->rows_in_array = numrows;
 542   result->samplesperrow = samplesperrow;
 543   result->maxaccess = maxaccess;
 544   result->pre_zero = pre_zero;
 545   result->b_s_open = FALSE;  /* no associated backing-store object */
 546   result->next = mem->virt_sarray_list; /* add to list of virtual arrays */
 547   mem->virt_sarray_list = result;
 548 
 549   return result;
 550 }
 551 
 552 
 553 METHODDEF(jvirt_barray_ptr)
 554 request_virt_barray (j_common_ptr cinfo, int pool_id, boolean pre_zero,
 555                      JDIMENSION blocksperrow, JDIMENSION numrows,
 556                      JDIMENSION maxaccess)
 557 /* Request a virtual 2-D coefficient-block array */
 558 {
 559   my_mem_ptr mem = (my_mem_ptr) cinfo->mem;
 560   jvirt_barray_ptr result;
 561 
 562   /* Only IMAGE-lifetime virtual arrays are currently supported */
 563   if (pool_id != JPOOL_IMAGE)
 564     ERREXIT1(cinfo, JERR_BAD_POOL_ID, pool_id); /* safety check */
 565 
 566   /* get control block */
 567   result = (jvirt_barray_ptr) alloc_small(cinfo, pool_id,
 568                                           SIZEOF(struct jvirt_barray_control));
 569 
 570   result->mem_buffer = NULL; /* marks array not yet realized */
 571   result->rows_in_array = numrows;
 572   result->blocksperrow = blocksperrow;
 573   result->maxaccess = maxaccess;
 574   result->pre_zero = pre_zero;
 575   result->b_s_open = FALSE;  /* no associated backing-store object */
 576   result->next = mem->virt_barray_list; /* add to list of virtual arrays */
 577   mem->virt_barray_list = result;
 578 
 579   return result;
 580 }
 581 
 582 
 583 METHODDEF(void)
 584 realize_virt_arrays (j_common_ptr cinfo)
 585 /* Allocate the in-memory buffers for any unrealized virtual arrays */
 586 {
 587   my_mem_ptr mem = (my_mem_ptr) cinfo->mem;
 588   long space_per_minheight, maximum_space, avail_mem;
 589   long minheights, max_minheights;
 590   jvirt_sarray_ptr sptr;
 591   jvirt_barray_ptr bptr;
 592 
 593   /* Compute the minimum space needed (maxaccess rows in each buffer)
 594    * and the maximum space needed (full image height in each buffer).
 595    * These may be of use to the system-dependent jpeg_mem_available routine.
 596    */
 597   space_per_minheight = 0;
 598   maximum_space = 0;
 599   for (sptr = mem->virt_sarray_list; sptr != NULL; sptr = sptr->next) {
 600     if (sptr->mem_buffer == NULL) { /* if not realized yet */
 601       space_per_minheight += (long) sptr->maxaccess *
 602                              (long) sptr->samplesperrow * SIZEOF(JSAMPLE);
 603       maximum_space += (long) sptr->rows_in_array *
 604                        (long) sptr->samplesperrow * SIZEOF(JSAMPLE);
 605     }
 606   }
 607   for (bptr = mem->virt_barray_list; bptr != NULL; bptr = bptr->next) {
 608     if (bptr->mem_buffer == NULL) { /* if not realized yet */
 609       space_per_minheight += (long) bptr->maxaccess *
 610                              (long) bptr->blocksperrow * SIZEOF(JBLOCK);
 611       maximum_space += (long) bptr->rows_in_array *
 612                        (long) bptr->blocksperrow * SIZEOF(JBLOCK);
 613     }
 614   }
 615 
 616   if (space_per_minheight <= 0)
 617     return;                     /* no unrealized arrays, no work */
 618 
 619   /* Determine amount of memory to actually use; this is system-dependent. */
 620   avail_mem = jpeg_mem_available(cinfo, space_per_minheight, maximum_space,
 621                                  mem->total_space_allocated);
 622 
 623   /* If the maximum space needed is available, make all the buffers full
 624    * height; otherwise parcel it out with the same number of minheights
 625    * in each buffer.
 626    */
 627   if (avail_mem >= maximum_space)
 628     max_minheights = 1000000000L;
 629   else {
 630     max_minheights = avail_mem / space_per_minheight;
 631     /* If there doesn't seem to be enough space, try to get the minimum
 632      * anyway.  This allows a "stub" implementation of jpeg_mem_available().
 633      */
 634     if (max_minheights <= 0)
 635       max_minheights = 1;
 636   }
 637 
 638   /* Allocate the in-memory buffers and initialize backing store as needed. */
 639 
 640   for (sptr = mem->virt_sarray_list; sptr != NULL; sptr = sptr->next) {
 641     if (sptr->mem_buffer == NULL) { /* if not realized yet */
 642       minheights = ((long) sptr->rows_in_array - 1L) / sptr->maxaccess + 1L;
 643       if (minheights <= max_minheights) {
 644         /* This buffer fits in memory */
 645         sptr->rows_in_mem = sptr->rows_in_array;
 646       } else {
 647         /* It doesn't fit in memory, create backing store. */
 648         sptr->rows_in_mem = (JDIMENSION) (max_minheights * sptr->maxaccess);
 649         jpeg_open_backing_store(cinfo, & sptr->b_s_info,
 650                                 (long) sptr->rows_in_array *
 651                                 (long) sptr->samplesperrow *
 652                                 (long) SIZEOF(JSAMPLE));
 653         sptr->b_s_open = TRUE;
 654       }
 655       sptr->mem_buffer = alloc_sarray(cinfo, JPOOL_IMAGE,
 656                                       sptr->samplesperrow, sptr->rows_in_mem);
 657       sptr->rowsperchunk = mem->last_rowsperchunk;
 658       sptr->cur_start_row = 0;
 659       sptr->first_undef_row = 0;
 660       sptr->dirty = FALSE;
 661     }
 662   }
 663 
 664   for (bptr = mem->virt_barray_list; bptr != NULL; bptr = bptr->next) {
 665     if (bptr->mem_buffer == NULL) { /* if not realized yet */
 666       minheights = ((long) bptr->rows_in_array - 1L) / bptr->maxaccess + 1L;
 667       if (minheights <= max_minheights) {
 668         /* This buffer fits in memory */
 669         bptr->rows_in_mem = bptr->rows_in_array;
 670       } else {
 671         /* It doesn't fit in memory, create backing store. */
 672         bptr->rows_in_mem = (JDIMENSION) (max_minheights * bptr->maxaccess);
 673         jpeg_open_backing_store(cinfo, & bptr->b_s_info,
 674                                 (long) bptr->rows_in_array *
 675                                 (long) bptr->blocksperrow *
 676                                 (long) SIZEOF(JBLOCK));
 677         bptr->b_s_open = TRUE;
 678       }
 679       bptr->mem_buffer = alloc_barray(cinfo, JPOOL_IMAGE,
 680                                       bptr->blocksperrow, bptr->rows_in_mem);
 681       bptr->rowsperchunk = mem->last_rowsperchunk;
 682       bptr->cur_start_row = 0;
 683       bptr->first_undef_row = 0;
 684       bptr->dirty = FALSE;
 685     }
 686   }
 687 }
 688 
 689 
 690 LOCAL(void)
 691 do_sarray_io (j_common_ptr cinfo, jvirt_sarray_ptr ptr, boolean writing)
 692 /* Do backing store read or write of a virtual sample array */
 693 {
 694   long bytesperrow, file_offset, byte_count, rows, thisrow, i;
 695 
 696   bytesperrow = (long) ptr->samplesperrow * SIZEOF(JSAMPLE);
 697   file_offset = ptr->cur_start_row * bytesperrow;
 698   /* Loop to read or write each allocation chunk in mem_buffer */
 699   for (i = 0; i < (long) ptr->rows_in_mem; i += ptr->rowsperchunk) {
 700     /* One chunk, but check for short chunk at end of buffer */
 701     rows = MIN((long) ptr->rowsperchunk, (long) ptr->rows_in_mem - i);
 702     /* Transfer no more than is currently defined */
 703     thisrow = (long) ptr->cur_start_row + i;
 704     rows = MIN(rows, (long) ptr->first_undef_row - thisrow);
 705     /* Transfer no more than fits in file */
 706     rows = MIN(rows, (long) ptr->rows_in_array - thisrow);
 707     if (rows <= 0)           /* this chunk might be past end of file! */
 708       break;
 709     byte_count = rows * bytesperrow;
 710     if (writing)
 711       (*ptr->b_s_info.write_backing_store) (cinfo, & ptr->b_s_info,
 712                                             (void FAR *) ptr->mem_buffer[i],
 713                                             file_offset, byte_count);
 714     else
 715       (*ptr->b_s_info.read_backing_store) (cinfo, & ptr->b_s_info,
 716                                            (void FAR *) ptr->mem_buffer[i],
 717                                            file_offset, byte_count);
 718     file_offset += byte_count;
 719   }
 720 }
 721 
 722 
 723 LOCAL(void)
 724 do_barray_io (j_common_ptr cinfo, jvirt_barray_ptr ptr, boolean writing)
 725 /* Do backing store read or write of a virtual coefficient-block array */
 726 {
 727   long bytesperrow, file_offset, byte_count, rows, thisrow, i;
 728 
 729   bytesperrow = (long) ptr->blocksperrow * SIZEOF(JBLOCK);
 730   file_offset = ptr->cur_start_row * bytesperrow;
 731   /* Loop to read or write each allocation chunk in mem_buffer */
 732   for (i = 0; i < (long) ptr->rows_in_mem; i += ptr->rowsperchunk) {
 733     /* One chunk, but check for short chunk at end of buffer */
 734     rows = MIN((long) ptr->rowsperchunk, (long) ptr->rows_in_mem - i);
 735     /* Transfer no more than is currently defined */
 736     thisrow = (long) ptr->cur_start_row + i;
 737     rows = MIN(rows, (long) ptr->first_undef_row - thisrow);
 738     /* Transfer no more than fits in file */
 739     rows = MIN(rows, (long) ptr->rows_in_array - thisrow);
 740     if (rows <= 0)           /* this chunk might be past end of file! */
 741       break;
 742     byte_count = rows * bytesperrow;
 743     if (writing)
 744       (*ptr->b_s_info.write_backing_store) (cinfo, & ptr->b_s_info,
 745                                             (void FAR *) ptr->mem_buffer[i],
 746                                             file_offset, byte_count);
 747     else
 748       (*ptr->b_s_info.read_backing_store) (cinfo, & ptr->b_s_info,
 749                                            (void FAR *) ptr->mem_buffer[i],
 750                                            file_offset, byte_count);
 751     file_offset += byte_count;
 752   }
 753 }
 754 
 755 
 756 METHODDEF(JSAMPARRAY)
 757 access_virt_sarray (j_common_ptr cinfo, jvirt_sarray_ptr ptr,
 758                     JDIMENSION start_row, JDIMENSION num_rows,
 759                     boolean writable)
 760 /* Access the part of a virtual sample array starting at start_row */
 761 /* and extending for num_rows rows.  writable is true if  */
 762 /* caller intends to modify the accessed area. */
 763 {
 764   JDIMENSION end_row = start_row + num_rows;
 765   JDIMENSION undef_row;
 766 
 767   /* debugging check */
 768   if (end_row > ptr->rows_in_array || num_rows > ptr->maxaccess ||
 769       ptr->mem_buffer == NULL)
 770     ERREXIT(cinfo, JERR_BAD_VIRTUAL_ACCESS);
 771 
 772   /* Make the desired part of the virtual array accessible */
 773   if (start_row < ptr->cur_start_row ||
 774       end_row > ptr->cur_start_row+ptr->rows_in_mem) {
 775     if (! ptr->b_s_open)
 776       ERREXIT(cinfo, JERR_VIRTUAL_BUG);
 777     /* Flush old buffer contents if necessary */
 778     if (ptr->dirty) {
 779       do_sarray_io(cinfo, ptr, TRUE);
 780       ptr->dirty = FALSE;
 781     }
 782     /* Decide what part of virtual array to access.
 783      * Algorithm: if target address > current window, assume forward scan,
 784      * load starting at target address.  If target address < current window,
 785      * assume backward scan, load so that target area is top of window.
 786      * Note that when switching from forward write to forward read, will have
 787      * start_row = 0, so the limiting case applies and we load from 0 anyway.
 788      */
 789     if (start_row > ptr->cur_start_row) {
 790       ptr->cur_start_row = start_row;
 791     } else {
 792       /* use long arithmetic here to avoid overflow & unsigned problems */
 793       long ltemp;
 794 
 795       ltemp = (long) end_row - (long) ptr->rows_in_mem;
 796       if (ltemp < 0)
 797         ltemp = 0;              /* don't fall off front end of file */
 798       ptr->cur_start_row = (JDIMENSION) ltemp;
 799     }
 800     /* Read in the selected part of the array.
 801      * During the initial write pass, we will do no actual read
 802      * because the selected part is all undefined.
 803      */
 804     do_sarray_io(cinfo, ptr, FALSE);
 805   }
 806   /* Ensure the accessed part of the array is defined; prezero if needed.
 807    * To improve locality of access, we only prezero the part of the array
 808    * that the caller is about to access, not the entire in-memory array.
 809    */
 810   if (ptr->first_undef_row < end_row) {
 811     if (ptr->first_undef_row < start_row) {
 812       if (writable)             /* writer skipped over a section of array */
 813         ERREXIT(cinfo, JERR_BAD_VIRTUAL_ACCESS);
 814       undef_row = start_row;    /* but reader is allowed to read ahead */
 815     } else {
 816       undef_row = ptr->first_undef_row;
 817     }
 818     if (writable)
 819       ptr->first_undef_row = end_row;
 820     if (ptr->pre_zero) {
 821       size_t bytesperrow = (size_t) ptr->samplesperrow * SIZEOF(JSAMPLE);
 822       undef_row -= ptr->cur_start_row; /* make indexes relative to buffer */
 823       end_row -= ptr->cur_start_row;
 824       while (undef_row < end_row) {
 825         FMEMZERO((void FAR *) ptr->mem_buffer[undef_row], bytesperrow);
 826         undef_row++;
 827       }
 828     } else {
 829       if (! writable)           /* reader looking at undefined data */
 830         ERREXIT(cinfo, JERR_BAD_VIRTUAL_ACCESS);
 831     }
 832   }
 833   /* Flag the buffer dirty if caller will write in it */
 834   if (writable)
 835     ptr->dirty = TRUE;
 836   /* Return address of proper part of the buffer */
 837   return ptr->mem_buffer + (start_row - ptr->cur_start_row);
 838 }
 839 
 840 
 841 METHODDEF(JBLOCKARRAY)
 842 access_virt_barray (j_common_ptr cinfo, jvirt_barray_ptr ptr,
 843                     JDIMENSION start_row, JDIMENSION num_rows,
 844                     boolean writable)
 845 /* Access the part of a virtual block array starting at start_row */
 846 /* and extending for num_rows rows.  writable is true if  */
 847 /* caller intends to modify the accessed area. */
 848 {
 849   JDIMENSION end_row = start_row + num_rows;
 850   JDIMENSION undef_row;
 851 
 852   /* debugging check */
 853   if (end_row > ptr->rows_in_array || num_rows > ptr->maxaccess ||
 854       ptr->mem_buffer == NULL)
 855     ERREXIT(cinfo, JERR_BAD_VIRTUAL_ACCESS);
 856 
 857   /* Make the desired part of the virtual array accessible */
 858   if (start_row < ptr->cur_start_row ||
 859       end_row > ptr->cur_start_row+ptr->rows_in_mem) {
 860     if (! ptr->b_s_open)
 861       ERREXIT(cinfo, JERR_VIRTUAL_BUG);
 862     /* Flush old buffer contents if necessary */
 863     if (ptr->dirty) {
 864       do_barray_io(cinfo, ptr, TRUE);
 865       ptr->dirty = FALSE;
 866     }
 867     /* Decide what part of virtual array to access.
 868      * Algorithm: if target address > current window, assume forward scan,
 869      * load starting at target address.  If target address < current window,
 870      * assume backward scan, load so that target area is top of window.
 871      * Note that when switching from forward write to forward read, will have
 872      * start_row = 0, so the limiting case applies and we load from 0 anyway.
 873      */
 874     if (start_row > ptr->cur_start_row) {
 875       ptr->cur_start_row = start_row;
 876     } else {
 877       /* use long arithmetic here to avoid overflow & unsigned problems */
 878       long ltemp;
 879 
 880       ltemp = (long) end_row - (long) ptr->rows_in_mem;
 881       if (ltemp < 0)
 882         ltemp = 0;              /* don't fall off front end of file */
 883       ptr->cur_start_row = (JDIMENSION) ltemp;
 884     }
 885     /* Read in the selected part of the array.
 886      * During the initial write pass, we will do no actual read
 887      * because the selected part is all undefined.
 888      */
 889     do_barray_io(cinfo, ptr, FALSE);
 890   }
 891   /* Ensure the accessed part of the array is defined; prezero if needed.
 892    * To improve locality of access, we only prezero the part of the array
 893    * that the caller is about to access, not the entire in-memory array.
 894    */
 895   if (ptr->first_undef_row < end_row) {
 896     if (ptr->first_undef_row < start_row) {
 897       if (writable)             /* writer skipped over a section of array */
 898         ERREXIT(cinfo, JERR_BAD_VIRTUAL_ACCESS);
 899       undef_row = start_row;    /* but reader is allowed to read ahead */
 900     } else {
 901       undef_row = ptr->first_undef_row;
 902     }
 903     if (writable)
 904       ptr->first_undef_row = end_row;
 905     if (ptr->pre_zero) {
 906       size_t bytesperrow = (size_t) ptr->blocksperrow * SIZEOF(JBLOCK);
 907       undef_row -= ptr->cur_start_row; /* make indexes relative to buffer */
 908       end_row -= ptr->cur_start_row;
 909       while (undef_row < end_row) {
 910         FMEMZERO((void FAR *) ptr->mem_buffer[undef_row], bytesperrow);
 911         undef_row++;
 912       }
 913     } else {
 914       if (! writable)           /* reader looking at undefined data */
 915         ERREXIT(cinfo, JERR_BAD_VIRTUAL_ACCESS);
 916     }
 917   }
 918   /* Flag the buffer dirty if caller will write in it */
 919   if (writable)
 920     ptr->dirty = TRUE;
 921   /* Return address of proper part of the buffer */
 922   return ptr->mem_buffer + (start_row - ptr->cur_start_row);
 923 }
 924 
 925 
 926 /*
 927  * Release all objects belonging to a specified pool.
 928  */
 929 
 930 METHODDEF(void)
 931 free_pool (j_common_ptr cinfo, int pool_id)
 932 {
 933   my_mem_ptr mem = (my_mem_ptr) cinfo->mem;
 934   small_pool_ptr shdr_ptr;
 935   large_pool_ptr lhdr_ptr;
 936   size_t space_freed;
 937 
 938   if (pool_id < 0 || pool_id >= JPOOL_NUMPOOLS)
 939     ERREXIT1(cinfo, JERR_BAD_POOL_ID, pool_id); /* safety check */
 940 
 941 #ifdef MEM_STATS
 942   if (cinfo->err->trace_level > 1)
 943     print_mem_stats(cinfo, pool_id); /* print pool's memory usage statistics */
 944 #endif
 945 
 946   /* If freeing IMAGE pool, close any virtual arrays first */
 947   if (pool_id == JPOOL_IMAGE) {
 948     jvirt_sarray_ptr sptr;
 949     jvirt_barray_ptr bptr;
 950 
 951     for (sptr = mem->virt_sarray_list; sptr != NULL; sptr = sptr->next) {
 952       if (sptr->b_s_open) {  /* there may be no backing store */
 953         sptr->b_s_open = FALSE;      /* prevent recursive close if error */
 954         (*sptr->b_s_info.close_backing_store) (cinfo, & sptr->b_s_info);
 955       }
 956     }
 957     mem->virt_sarray_list = NULL;
 958     for (bptr = mem->virt_barray_list; bptr != NULL; bptr = bptr->next) {
 959       if (bptr->b_s_open) {  /* there may be no backing store */
 960         bptr->b_s_open = FALSE;      /* prevent recursive close if error */
 961         (*bptr->b_s_info.close_backing_store) (cinfo, & bptr->b_s_info);
 962       }
 963     }
 964     mem->virt_barray_list = NULL;
 965   }
 966 
 967   /* Release large objects */
 968   lhdr_ptr = mem->large_list[pool_id];
 969   mem->large_list[pool_id] = NULL;
 970 
 971   while (lhdr_ptr != NULL) {
 972     large_pool_ptr next_lhdr_ptr = lhdr_ptr->hdr.next;
 973     space_freed = lhdr_ptr->hdr.bytes_used +
 974                   lhdr_ptr->hdr.bytes_left +
 975                   SIZEOF(large_pool_hdr);
 976     jpeg_free_large(cinfo, (void FAR *) lhdr_ptr, space_freed);
 977     mem->total_space_allocated -= space_freed;
 978     lhdr_ptr = next_lhdr_ptr;
 979   }
 980 
 981   /* Release small objects */
 982   shdr_ptr = mem->small_list[pool_id];
 983   mem->small_list[pool_id] = NULL;
 984 
 985   while (shdr_ptr != NULL) {
 986     small_pool_ptr next_shdr_ptr = shdr_ptr->hdr.next;
 987     space_freed = shdr_ptr->hdr.bytes_used +
 988                   shdr_ptr->hdr.bytes_left +
 989                   SIZEOF(small_pool_hdr);
 990     jpeg_free_small(cinfo, (void *) shdr_ptr, space_freed);
 991     mem->total_space_allocated -= space_freed;
 992     shdr_ptr = next_shdr_ptr;
 993   }
 994 }
 995 
 996 
 997 /*
 998  * Close up shop entirely.
 999  * Note that this cannot be called unless cinfo->mem is non-NULL.
1000  */
1001 
1002 METHODDEF(void)
1003 self_destruct (j_common_ptr cinfo)
1004 {
1005   int pool;
1006 
1007   /* Close all backing store, release all memory.
1008    * Releasing pools in reverse order might help avoid fragmentation
1009    * with some (brain-damaged) malloc libraries.
1010    */
1011   for (pool = JPOOL_NUMPOOLS-1; pool >= JPOOL_PERMANENT; pool--) {
1012     free_pool(cinfo, pool);
1013   }
1014 
1015   /* Release the memory manager control block too. */
1016   jpeg_free_small(cinfo, (void *) cinfo->mem, SIZEOF(my_memory_mgr));
1017   cinfo->mem = NULL;         /* ensures I will be called only once */
1018 
1019   jpeg_mem_term(cinfo);         /* system-dependent cleanup */
1020 }
1021 
1022 
1023 /*
1024  * Memory manager initialization.
1025  * When this is called, only the error manager pointer is valid in cinfo!
1026  */
1027 
1028 GLOBAL(void)
1029 jinit_memory_mgr (j_common_ptr cinfo)
1030 {
1031   my_mem_ptr mem;
1032   long max_to_use;
1033   int pool;
1034   size_t test_mac;
1035 
1036   cinfo->mem = NULL;         /* for safety if init fails */
1037 
1038   /* Check for configuration errors.
1039    * SIZEOF(ALIGN_TYPE) should be a power of 2; otherwise, it probably
1040    * doesn't reflect any real hardware alignment requirement.
1041    * The test is a little tricky: for X>0, X and X-1 have no one-bits
1042    * in common if and only if X is a power of 2, ie has only one one-bit.
1043    * Some compilers may give an "unreachable code" warning here; ignore it.
1044    */
1045   if ((SIZEOF(ALIGN_TYPE) & (SIZEOF(ALIGN_TYPE)-1)) != 0)
1046     ERREXIT(cinfo, JERR_BAD_ALIGN_TYPE);
1047   /* MAX_ALLOC_CHUNK must be representable as type size_t, and must be
1048    * a multiple of SIZEOF(ALIGN_TYPE).
1049    * Again, an "unreachable code" warning may be ignored here.
1050    * But a "constant too large" warning means you need to fix MAX_ALLOC_CHUNK.
1051    */
1052   test_mac = (size_t) MAX_ALLOC_CHUNK;
1053   if ((long) test_mac != MAX_ALLOC_CHUNK ||
1054       (MAX_ALLOC_CHUNK % SIZEOF(ALIGN_TYPE)) != 0)
1055     ERREXIT(cinfo, JERR_BAD_ALLOC_CHUNK);
1056 
1057   max_to_use = jpeg_mem_init(cinfo); /* system-dependent initialization */
1058 
1059   /* Attempt to allocate memory manager's control block */
1060   mem = (my_mem_ptr) jpeg_get_small(cinfo, SIZEOF(my_memory_mgr));
1061 
1062   if (mem == NULL) {
1063     jpeg_mem_term(cinfo);       /* system-dependent cleanup */
1064     ERREXIT1(cinfo, JERR_OUT_OF_MEMORY, 0);
1065   }
1066 
1067   /* OK, fill in the method pointers */
1068   mem->pub.alloc_small = alloc_small;
1069   mem->pub.alloc_large = alloc_large;
1070   mem->pub.alloc_sarray = alloc_sarray;
1071   mem->pub.alloc_barray = alloc_barray;
1072   mem->pub.request_virt_sarray = request_virt_sarray;
1073   mem->pub.request_virt_barray = request_virt_barray;
1074   mem->pub.realize_virt_arrays = realize_virt_arrays;
1075   mem->pub.access_virt_sarray = access_virt_sarray;
1076   mem->pub.access_virt_barray = access_virt_barray;
1077   mem->pub.free_pool = free_pool;
1078   mem->pub.self_destruct = self_destruct;
1079 
1080   /* Make MAX_ALLOC_CHUNK accessible to other modules */
1081   mem->pub.max_alloc_chunk = MAX_ALLOC_CHUNK;
1082 
1083   /* Initialize working state */
1084   mem->pub.max_memory_to_use = max_to_use;
1085 
1086   for (pool = JPOOL_NUMPOOLS-1; pool >= JPOOL_PERMANENT; pool--) {
1087     mem->small_list[pool] = NULL;
1088     mem->large_list[pool] = NULL;
1089   }
1090   mem->virt_sarray_list = NULL;
1091   mem->virt_barray_list = NULL;
1092 
1093   mem->total_space_allocated = SIZEOF(my_memory_mgr);
1094 
1095   /* Declare ourselves open for business */
1096   cinfo->mem = & mem->pub;
1097 
1098   /* Check for an environment variable JPEGMEM; if found, override the
1099    * default max_memory setting from jpeg_mem_init.  Note that the
1100    * surrounding application may again override this value.
1101    * If your system doesn't support getenv(), define NO_GETENV to disable
1102    * this feature.
1103    */
1104 #ifndef NO_GETENV
1105   { char * memenv;
1106 
1107     if ((memenv = getenv("JPEGMEM")) != NULL) {
1108       char ch = 'x';
1109 
1110       if (sscanf(memenv, "%ld%c", &max_to_use, &ch) > 0) {
1111         if (ch == 'm' || ch == 'M')
1112           max_to_use *= 1000L;
1113         mem->pub.max_memory_to_use = max_to_use * 1000L;
1114       }
1115     }
1116   }
1117 #endif
1118 
1119 }
--- EOF ---