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() */
  35 extern 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 
  89 typedef union small_pool_struct * small_pool_ptr;
  90 
  91 typedef 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 
 100 typedef union large_pool_struct FAR * large_pool_ptr;
 101 
 102 typedef 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 
 116 typedef 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 
 140 typedef 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 
 150 struct 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 
 166 struct 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 
 185 LOCAL(void)
 186 print_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 
 216 LOCAL(void)
 217 out_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 
 241 static const size_t first_pool_slop[JPOOL_NUMPOOLS] =
 242 {
 243         1600,                   /* first PERMANENT pool */
 244         16000                   /* first IMAGE pool */
 245 };
 246 
 247 static 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 
 256 METHODDEF(void *)
 257 alloc_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 
 341 METHODDEF(void FAR *)
 342 alloc_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 
 394 METHODDEF(JSAMPARRAY)
 395 alloc_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 
 442 METHODDEF(JBLOCKARRAY)
 443 alloc_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 
 522 METHODDEF(jvirt_sarray_ptr)
 523 request_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 
 552 METHODDEF(jvirt_barray_ptr)
 553 request_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 
 582 METHODDEF(void)
 583 realize_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 
 689 LOCAL(void)
 690 do_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 
 722 LOCAL(void)
 723 do_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 
 755 METHODDEF(JSAMPARRAY)
 756 access_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 
 840 METHODDEF(JBLOCKARRAY)
 841 access_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 
 929 METHODDEF(void)
 930 free_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 
1001 METHODDEF(void)
1002 self_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 
1027 GLOBAL(void)
1028 jinit_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 }
--- EOF ---