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jmemmgr.c
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00001 /*
00002  * jmemmgr.c
00003  *
00004  * Copyright (C) 1991-1997, Thomas G. Lane.
00005  * This file is part of the Independent JPEG Group's software.
00006  * For conditions of distribution and use, see the accompanying README file.
00007  *
00008  * This file contains the JPEG system-independent memory management
00009  * routines.  This code is usable across a wide variety of machines; most
00010  * of the system dependencies have been isolated in a separate file.
00011  * The major functions provided here are:
00012  *   * pool-based allocation and freeing of memory;
00013  *   * policy decisions about how to divide available memory among the
00014  *     virtual arrays;
00015  *   * control logic for swapping virtual arrays between main memory and
00016  *     backing storage.
00017  * The separate system-dependent file provides the actual backing-storage
00018  * access code, and it contains the policy decision about how much total
00019  * main memory to use.
00020  * This file is system-dependent in the sense that some of its functions
00021  * are unnecessary in some systems.  For example, if there is enough virtual
00022  * memory so that backing storage will never be used, much of the virtual
00023  * array control logic could be removed.  (Of course, if you have that much
00024  * memory then you shouldn't care about a little bit of unused code...)
00025  */
00026 
00027 #define JPEG_INTERNALS
00028 #define AM_MEMORY_MANAGER   /* we define jvirt_Xarray_control structs */
00029 #include "jinclude.h"
00030 #include "jpeglib.h"
00031 #include "jmemsys.h"        /* import the system-dependent declarations */
00032 
00033 #ifndef NO_GETENV
00034 #ifndef HAVE_STDLIB_H              /* <stdlib.h> should declare getenv() */
00035 extern char * getenv JPP((const char * name));
00036 #endif
00037 #endif
00038 
00039 
00040 /*
00041  * Some important notes:
00042  *   The allocation routines provided here must never return NULL.
00043  *   They should exit to error_exit if unsuccessful.
00044  *
00045  *   It's not a good idea to try to merge the sarray and barray routines,
00046  *   even though they are textually almost the same, because samples are
00047  *   usually stored as bytes while coefficients are shorts or ints.  Thus,
00048  *   in machines where byte pointers have a different representation from
00049  *   word pointers, the resulting machine code could not be the same.
00050  */
00051 
00052 
00053 /*
00054  * Many machines require storage alignment: longs must start on 4-byte
00055  * boundaries, doubles on 8-byte boundaries, etc.  On such machines, malloc()
00056  * always returns pointers that are multiples of the worst-case alignment
00057  * requirement, and we had better do so too.
00058  * There isn't any really portable way to determine the worst-case alignment
00059  * requirement.  This module assumes that the alignment requirement is
00060  * multiples of sizeof(ALIGN_TYPE).
00061  * By default, we define ALIGN_TYPE as double.  This is necessary on some
00062  * workstations (where doubles really do need 8-byte alignment) and will work
00063  * fine on nearly everything.  If your machine has lesser alignment needs,
00064  * you can save a few bytes by making ALIGN_TYPE smaller.
00065  * The only place I know of where this will NOT work is certain Macintosh
00066  * 680x0 compilers that define double as a 10-byte IEEE extended float.
00067  * Doing 10-byte alignment is counterproductive because longwords won't be
00068  * aligned well.  Put "#define ALIGN_TYPE long" in jconfig.h if you have
00069  * such a compiler.
00070  */
00071 
00072 #ifndef ALIGN_TYPE          /* so can override from jconfig.h */
00073 #define ALIGN_TYPE  double
00074 #endif
00075 
00076 
00077 /*
00078  * We allocate objects from "pools", where each pool is gotten with a single
00079  * request to jpeg_get_small() or jpeg_get_large().  There is no per-object
00080  * overhead within a pool, except for alignment padding.  Each pool has a
00081  * header with a link to the next pool of the same class.
00082  * Small and large pool headers are identical except that the latter's
00083  * link pointer must be FAR on 80x86 machines.
00084  * Notice that the "real" header fields are union'ed with a dummy ALIGN_TYPE
00085  * field.  This forces the compiler to make SIZEOF(small_pool_hdr) a multiple
00086  * of the alignment requirement of ALIGN_TYPE.
00087  */
00088 
00089 typedef union small_pool_struct * small_pool_ptr;
00090 
00091 typedef union small_pool_struct {
00092   struct {
00093     small_pool_ptr next;    /* next in list of pools */
00094     size_t bytes_used;             /* how many bytes already used within pool */
00095     size_t bytes_left;             /* bytes still available in this pool */
00096   } hdr;
00097   ALIGN_TYPE dummy;         /* included in union to ensure alignment */
00098 } small_pool_hdr;
00099 
00100 typedef union large_pool_struct FAR * large_pool_ptr;
00101 
00102 typedef union large_pool_struct {
00103   struct {
00104     large_pool_ptr next;    /* next in list of pools */
00105     size_t bytes_used;             /* how many bytes already used within pool */
00106     size_t bytes_left;             /* bytes still available in this pool */
00107   } hdr;
00108   ALIGN_TYPE dummy;         /* included in union to ensure alignment */
00109 } large_pool_hdr;
00110 
00111 
00112 /*
00113  * Here is the full definition of a memory manager object.
00114  */
00115 
00116 typedef struct {
00117   struct jpeg_memory_mgr pub;      /* public fields */
00118 
00119   /* Each pool identifier (lifetime class) names a linked list of pools. */
00120   small_pool_ptr small_list[JPOOL_NUMPOOLS];
00121   large_pool_ptr large_list[JPOOL_NUMPOOLS];
00122 
00123   /* Since we only have one lifetime class of virtual arrays, only one
00124    * linked list is necessary (for each datatype).  Note that the virtual
00125    * array control blocks being linked together are actually stored somewhere
00126    * in the small-pool list.
00127    */
00128   jvirt_sarray_ptr virt_sarray_list;
00129   jvirt_barray_ptr virt_barray_list;
00130 
00131   /* This counts total space obtained from jpeg_get_small/large */
00132   long total_space_allocated;
00133 
00134   /* alloc_sarray and alloc_barray set this value for use by virtual
00135    * array routines.
00136    */
00137   JDIMENSION last_rowsperchunk;    /* from most recent alloc_sarray/barray */
00138 } my_memory_mgr;
00139 
00140 typedef my_memory_mgr * my_mem_ptr;
00141 
00142 
00143 /*
00144  * The control blocks for virtual arrays.
00145  * Note that these blocks are allocated in the "small" pool area.
00146  * System-dependent info for the associated backing store (if any) is hidden
00147  * inside the backing_store_info struct.
00148  */
00149 
00150 struct jvirt_sarray_control {
00151   JSAMPARRAY mem_buffer;    /* => the in-memory buffer */
00152   JDIMENSION rows_in_array; /* total virtual array height */
00153   JDIMENSION samplesperrow; /* width of array (and of memory buffer) */
00154   JDIMENSION maxaccess;            /* max rows accessed by access_virt_sarray */
00155   JDIMENSION rows_in_mem;   /* height of memory buffer */
00156   JDIMENSION rowsperchunk;  /* allocation chunk size in mem_buffer */
00157   JDIMENSION cur_start_row; /* first logical row # in the buffer */
00158   JDIMENSION first_undef_row;      /* row # of first uninitialized row */
00159   boolean pre_zero;         /* pre-zero mode requested? */
00160   boolean dirty;            /* do current buffer contents need written? */
00161   boolean b_s_open;         /* is backing-store data valid? */
00162   jvirt_sarray_ptr next;    /* link to next virtual sarray control block */
00163   backing_store_info b_s_info;     /* System-dependent control info */
00164 };
00165 
00166 struct jvirt_barray_control {
00167   JBLOCKARRAY mem_buffer;   /* => the in-memory buffer */
00168   JDIMENSION rows_in_array; /* total virtual array height */
00169   JDIMENSION blocksperrow;  /* width of array (and of memory buffer) */
00170   JDIMENSION maxaccess;            /* max rows accessed by access_virt_barray */
00171   JDIMENSION rows_in_mem;   /* height of memory buffer */
00172   JDIMENSION rowsperchunk;  /* allocation chunk size in mem_buffer */
00173   JDIMENSION cur_start_row; /* first logical row # in the buffer */
00174   JDIMENSION first_undef_row;      /* row # of first uninitialized row */
00175   boolean pre_zero;         /* pre-zero mode requested? */
00176   boolean dirty;            /* do current buffer contents need written? */
00177   boolean b_s_open;         /* is backing-store data valid? */
00178   jvirt_barray_ptr next;    /* link to next virtual barray control block */
00179   backing_store_info b_s_info;     /* System-dependent control info */
00180 };
00181 
00182 
00183 #ifdef MEM_STATS            /* optional extra stuff for statistics */
00184 
00185 LOCAL(void)
00186 print_mem_stats (j_common_ptr cinfo, int pool_id)
00187 {
00188   my_mem_ptr mem = (my_mem_ptr) cinfo->mem;
00189   small_pool_ptr shdr_ptr;
00190   large_pool_ptr lhdr_ptr;
00191 
00192   /* Since this is only a debugging stub, we can cheat a little by using
00193    * fprintf directly rather than going through the trace message code.
00194    * This is helpful because message parm array can't handle longs.
00195    */
00196   fprintf(stderr, "Freeing pool %d, total space = %ld\n",
00197          pool_id, mem->total_space_allocated);
00198 
00199   for (lhdr_ptr = mem->large_list[pool_id]; lhdr_ptr != NULL;
00200        lhdr_ptr = lhdr_ptr->hdr.next) {
00201     fprintf(stderr, "  Large chunk used %ld\n",
00202            (long) lhdr_ptr->hdr.bytes_used);
00203   }
00204 
00205   for (shdr_ptr = mem->small_list[pool_id]; shdr_ptr != NULL;
00206        shdr_ptr = shdr_ptr->hdr.next) {
00207     fprintf(stderr, "  Small chunk used %ld free %ld\n",
00208            (long) shdr_ptr->hdr.bytes_used,
00209            (long) shdr_ptr->hdr.bytes_left);
00210   }
00211 }
00212 
00213 #endif /* MEM_STATS */
00214 
00215 
00216 LOCAL(void)
00217 out_of_memory (j_common_ptr cinfo, int which)
00218 /* Report an out-of-memory error and stop execution */
00219 /* If we compiled MEM_STATS support, report alloc requests before dying */
00220 {
00221 #ifdef MEM_STATS
00222   cinfo->err->trace_level = 2;     /* force self_destruct to report stats */
00223 #endif
00224   ERREXIT1(cinfo, JERR_OUT_OF_MEMORY, which);
00225 }
00226 
00227 
00228 /*
00229  * Allocation of "small" objects.
00230  *
00231  * For these, we use pooled storage.  When a new pool must be created,
00232  * we try to get enough space for the current request plus a "slop" factor,
00233  * where the slop will be the amount of leftover space in the new pool.
00234  * The speed vs. space tradeoff is largely determined by the slop values.
00235  * A different slop value is provided for each pool class (lifetime),
00236  * and we also distinguish the first pool of a class from later ones.
00237  * NOTE: the values given work fairly well on both 16- and 32-bit-int
00238  * machines, but may be too small if longs are 64 bits or more.
00239  */
00240 
00241 static const size_t first_pool_slop[JPOOL_NUMPOOLS] = 
00242 {
00243        1600,                /* first PERMANENT pool */
00244        16000                /* first IMAGE pool */
00245 };
00246 
00247 static const size_t extra_pool_slop[JPOOL_NUMPOOLS] = 
00248 {
00249        0,                   /* additional PERMANENT pools */
00250        5000                 /* additional IMAGE pools */
00251 };
00252 
00253 #define MIN_SLOP  50        /* greater than 0 to avoid futile looping */
00254 
00255 
00256 METHODDEF(void *)
00257 alloc_small (j_common_ptr cinfo, int pool_id, size_t sizeofobject)
00258 /* Allocate a "small" object */
00259 {
00260   my_mem_ptr mem = (my_mem_ptr) cinfo->mem;
00261   small_pool_ptr hdr_ptr, prev_hdr_ptr;
00262   char * data_ptr;
00263   size_t odd_bytes, min_request, slop;
00264 
00265   /* Check for unsatisfiable request (do now to ensure no overflow below) */
00266   if (sizeofobject > (size_t) (MAX_ALLOC_CHUNK-SIZEOF(small_pool_hdr)))
00267     out_of_memory(cinfo, 1);       /* request exceeds malloc's ability */
00268 
00269   /* Round up the requested size to a multiple of SIZEOF(ALIGN_TYPE) */
00270   odd_bytes = sizeofobject % SIZEOF(ALIGN_TYPE);
00271   if (odd_bytes > 0)
00272     sizeofobject += SIZEOF(ALIGN_TYPE) - odd_bytes;
00273 
00274   /* See if space is available in any existing pool */
00275   if (pool_id < 0 || pool_id >= JPOOL_NUMPOOLS)
00276     ERREXIT1(cinfo, JERR_BAD_POOL_ID, pool_id);  /* safety check */
00277   prev_hdr_ptr = NULL;
00278   hdr_ptr = mem->small_list[pool_id];
00279   while (hdr_ptr != NULL) {
00280     if (hdr_ptr->hdr.bytes_left >= sizeofobject)
00281       break;                /* found pool with enough space */
00282     prev_hdr_ptr = hdr_ptr;
00283     hdr_ptr = hdr_ptr->hdr.next;
00284   }
00285 
00286   /* Time to make a new pool? */
00287   if (hdr_ptr == NULL) {
00288     /* min_request is what we need now, slop is what will be leftover */
00289     min_request = sizeofobject + SIZEOF(small_pool_hdr);
00290     if (prev_hdr_ptr == NULL)      /* first pool in class? */
00291       slop = first_pool_slop[pool_id];
00292     else
00293       slop = extra_pool_slop[pool_id];
00294     /* Don't ask for more than MAX_ALLOC_CHUNK */
00295     if (slop > (size_t) (MAX_ALLOC_CHUNK-min_request))
00296       slop = (size_t) (MAX_ALLOC_CHUNK-min_request);
00297     /* Try to get space, if fail reduce slop and try again */
00298     for (;;) {
00299       hdr_ptr = (small_pool_ptr) jpeg_get_small(cinfo, min_request + slop);
00300       if (hdr_ptr != NULL)
00301        break;
00302       slop /= 2;
00303       if (slop < MIN_SLOP)  /* give up when it gets real small */
00304        out_of_memory(cinfo, 2); /* jpeg_get_small failed */
00305     }
00306     mem->total_space_allocated += min_request + slop;
00307     /* Success, initialize the new pool header and add to end of list */
00308     hdr_ptr->hdr.next = NULL;
00309     hdr_ptr->hdr.bytes_used = 0;
00310     hdr_ptr->hdr.bytes_left = sizeofobject + slop;
00311     if (prev_hdr_ptr == NULL)      /* first pool in class? */
00312       mem->small_list[pool_id] = hdr_ptr;
00313     else
00314       prev_hdr_ptr->hdr.next = hdr_ptr;
00315   }
00316 
00317   /* OK, allocate the object from the current pool */
00318   data_ptr = (char *) (hdr_ptr + 1); /* point to first data byte in pool */
00319   data_ptr += hdr_ptr->hdr.bytes_used; /* point to place for object */
00320   hdr_ptr->hdr.bytes_used += sizeofobject;
00321   hdr_ptr->hdr.bytes_left -= sizeofobject;
00322 
00323   return (void *) data_ptr;
00324 }
00325 
00326 
00327 /*
00328  * Allocation of "large" objects.
00329  *
00330  * The external semantics of these are the same as "small" objects,
00331  * except that FAR pointers are used on 80x86.  However the pool
00332  * management heuristics are quite different.  We assume that each
00333  * request is large enough that it may as well be passed directly to
00334  * jpeg_get_large; the pool management just links everything together
00335  * so that we can free it all on demand.
00336  * Note: the major use of "large" objects is in JSAMPARRAY and JBLOCKARRAY
00337  * structures.  The routines that create these structures (see below)
00338  * deliberately bunch rows together to ensure a large request size.
00339  */
00340 
00341 METHODDEF(void FAR *)
00342 alloc_large (j_common_ptr cinfo, int pool_id, size_t sizeofobject)
00343 /* Allocate a "large" object */
00344 {
00345   my_mem_ptr mem = (my_mem_ptr) cinfo->mem;
00346   large_pool_ptr hdr_ptr;
00347   size_t odd_bytes;
00348 
00349   /* Check for unsatisfiable request (do now to ensure no overflow below) */
00350   if (sizeofobject > (size_t) (MAX_ALLOC_CHUNK-SIZEOF(large_pool_hdr)))
00351     out_of_memory(cinfo, 3);       /* request exceeds malloc's ability */
00352 
00353   /* Round up the requested size to a multiple of SIZEOF(ALIGN_TYPE) */
00354   odd_bytes = sizeofobject % SIZEOF(ALIGN_TYPE);
00355   if (odd_bytes > 0)
00356     sizeofobject += SIZEOF(ALIGN_TYPE) - odd_bytes;
00357 
00358   /* Always make a new pool */
00359   if (pool_id < 0 || pool_id >= JPOOL_NUMPOOLS)
00360     ERREXIT1(cinfo, JERR_BAD_POOL_ID, pool_id);  /* safety check */
00361 
00362   hdr_ptr = (large_pool_ptr) jpeg_get_large(cinfo, sizeofobject +
00363                                        SIZEOF(large_pool_hdr));
00364   if (hdr_ptr == NULL)
00365     out_of_memory(cinfo, 4);       /* jpeg_get_large failed */
00366   mem->total_space_allocated += sizeofobject + SIZEOF(large_pool_hdr);
00367 
00368   /* Success, initialize the new pool header and add to list */
00369   hdr_ptr->hdr.next = mem->large_list[pool_id];
00370   /* We maintain space counts in each pool header for statistical purposes,
00371    * even though they are not needed for allocation.
00372    */
00373   hdr_ptr->hdr.bytes_used = sizeofobject;
00374   hdr_ptr->hdr.bytes_left = 0;
00375   mem->large_list[pool_id] = hdr_ptr;
00376 
00377   return (void FAR *) (hdr_ptr + 1); /* point to first data byte in pool */
00378 }
00379 
00380 
00381 /*
00382  * Creation of 2-D sample arrays.
00383  * The pointers are in near heap, the samples themselves in FAR heap.
00384  *
00385  * To minimize allocation overhead and to allow I/O of large contiguous
00386  * blocks, we allocate the sample rows in groups of as many rows as possible
00387  * without exceeding MAX_ALLOC_CHUNK total bytes per allocation request.
00388  * NB: the virtual array control routines, later in this file, know about
00389  * this chunking of rows.  The rowsperchunk value is left in the mem manager
00390  * object so that it can be saved away if this sarray is the workspace for
00391  * a virtual array.
00392  */
00393 
00394 METHODDEF(JSAMPARRAY)
00395 alloc_sarray (j_common_ptr cinfo, int pool_id,
00396              JDIMENSION samplesperrow, JDIMENSION numrows)
00397 /* Allocate a 2-D sample array */
00398 {
00399   my_mem_ptr mem = (my_mem_ptr) cinfo->mem;
00400   JSAMPARRAY result;
00401   JSAMPROW workspace;
00402   JDIMENSION rowsperchunk, currow, i;
00403   long ltemp;
00404 
00405   /* Calculate max # of rows allowed in one allocation chunk */
00406   ltemp = (MAX_ALLOC_CHUNK-SIZEOF(large_pool_hdr)) /
00407          ((long) samplesperrow * SIZEOF(JSAMPLE));
00408   if (ltemp <= 0)
00409     ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);
00410   if (ltemp < (long) numrows)
00411     rowsperchunk = (JDIMENSION) ltemp;
00412   else
00413     rowsperchunk = numrows;
00414   mem->last_rowsperchunk = rowsperchunk;
00415 
00416   /* Get space for row pointers (small object) */
00417   result = (JSAMPARRAY) alloc_small(cinfo, pool_id,
00418                                 (size_t) (numrows * SIZEOF(JSAMPROW)));
00419 
00420   /* Get the rows themselves (large objects) */
00421   currow = 0;
00422   while (currow < numrows) {
00423     rowsperchunk = MIN(rowsperchunk, numrows - currow);
00424     workspace = (JSAMPROW) alloc_large(cinfo, pool_id,
00425        (size_t) ((size_t) rowsperchunk * (size_t) samplesperrow
00426                 * SIZEOF(JSAMPLE)));
00427     for (i = rowsperchunk; i > 0; i--) {
00428       result[currow++] = workspace;
00429       workspace += samplesperrow;
00430     }
00431   }
00432 
00433   return result;
00434 }
00435 
00436 
00437 /*
00438  * Creation of 2-D coefficient-block arrays.
00439  * This is essentially the same as the code for sample arrays, above.
00440  */
00441 
00442 METHODDEF(JBLOCKARRAY)
00443 alloc_barray (j_common_ptr cinfo, int pool_id,
00444              JDIMENSION blocksperrow, JDIMENSION numrows)
00445 /* Allocate a 2-D coefficient-block array */
00446 {
00447   my_mem_ptr mem = (my_mem_ptr) cinfo->mem;
00448   JBLOCKARRAY result;
00449   JBLOCKROW workspace;
00450   JDIMENSION rowsperchunk, currow, i;
00451   long ltemp;
00452 
00453   /* Calculate max # of rows allowed in one allocation chunk */
00454   ltemp = (MAX_ALLOC_CHUNK-SIZEOF(large_pool_hdr)) /
00455          ((long) blocksperrow * SIZEOF(JBLOCK));
00456   if (ltemp <= 0)
00457     ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);
00458   if (ltemp < (long) numrows)
00459     rowsperchunk = (JDIMENSION) ltemp;
00460   else
00461     rowsperchunk = numrows;
00462   mem->last_rowsperchunk = rowsperchunk;
00463 
00464   /* Get space for row pointers (small object) */
00465   result = (JBLOCKARRAY) alloc_small(cinfo, pool_id,
00466                                  (size_t) (numrows * SIZEOF(JBLOCKROW)));
00467 
00468   /* Get the rows themselves (large objects) */
00469   currow = 0;
00470   while (currow < numrows) {
00471     rowsperchunk = MIN(rowsperchunk, numrows - currow);
00472     workspace = (JBLOCKROW) alloc_large(cinfo, pool_id,
00473        (size_t) ((size_t) rowsperchunk * (size_t) blocksperrow
00474                 * SIZEOF(JBLOCK)));
00475     for (i = rowsperchunk; i > 0; i--) {
00476       result[currow++] = workspace;
00477       workspace += blocksperrow;
00478     }
00479   }
00480 
00481   return result;
00482 }
00483 
00484 
00485 /*
00486  * About virtual array management:
00487  *
00488  * The above "normal" array routines are only used to allocate strip buffers
00489  * (as wide as the image, but just a few rows high).  Full-image-sized buffers
00490  * are handled as "virtual" arrays.  The array is still accessed a strip at a
00491  * time, but the memory manager must save the whole array for repeated
00492  * accesses.  The intended implementation is that there is a strip buffer in
00493  * memory (as high as is possible given the desired memory limit), plus a
00494  * backing file that holds the rest of the array.
00495  *
00496  * The request_virt_array routines are told the total size of the image and
00497  * the maximum number of rows that will be accessed at once.  The in-memory
00498  * buffer must be at least as large as the maxaccess value.
00499  *
00500  * The request routines create control blocks but not the in-memory buffers.
00501  * That is postponed until realize_virt_arrays is called.  At that time the
00502  * total amount of space needed is known (approximately, anyway), so free
00503  * memory can be divided up fairly.
00504  *
00505  * The access_virt_array routines are responsible for making a specific strip
00506  * area accessible (after reading or writing the backing file, if necessary).
00507  * Note that the access routines are told whether the caller intends to modify
00508  * the accessed strip; during a read-only pass this saves having to rewrite
00509  * data to disk.  The access routines are also responsible for pre-zeroing
00510  * any newly accessed rows, if pre-zeroing was requested.
00511  *
00512  * In current usage, the access requests are usually for nonoverlapping
00513  * strips; that is, successive access start_row numbers differ by exactly
00514  * num_rows = maxaccess.  This means we can get good performance with simple
00515  * buffer dump/reload logic, by making the in-memory buffer be a multiple
00516  * of the access height; then there will never be accesses across bufferload
00517  * boundaries.  The code will still work with overlapping access requests,
00518  * but it doesn't handle bufferload overlaps very efficiently.
00519  */
00520 
00521 
00522 METHODDEF(jvirt_sarray_ptr)
00523 request_virt_sarray (j_common_ptr cinfo, int pool_id, boolean pre_zero,
00524                    JDIMENSION samplesperrow, JDIMENSION numrows,
00525                    JDIMENSION maxaccess)
00526 /* Request a virtual 2-D sample array */
00527 {
00528   my_mem_ptr mem = (my_mem_ptr) cinfo->mem;
00529   jvirt_sarray_ptr result;
00530 
00531   /* Only IMAGE-lifetime virtual arrays are currently supported */
00532   if (pool_id != JPOOL_IMAGE)
00533     ERREXIT1(cinfo, JERR_BAD_POOL_ID, pool_id);  /* safety check */
00534 
00535   /* get control block */
00536   result = (jvirt_sarray_ptr) alloc_small(cinfo, pool_id,
00537                                      SIZEOF(struct jvirt_sarray_control));
00538 
00539   result->mem_buffer = NULL;       /* marks array not yet realized */
00540   result->rows_in_array = numrows;
00541   result->samplesperrow = samplesperrow;
00542   result->maxaccess = maxaccess;
00543   result->pre_zero = pre_zero;
00544   result->b_s_open = FALSE; /* no associated backing-store object */
00545   result->next = mem->virt_sarray_list; /* add to list of virtual arrays */
00546   mem->virt_sarray_list = result;
00547 
00548   return result;
00549 }
00550 
00551 
00552 METHODDEF(jvirt_barray_ptr)
00553 request_virt_barray (j_common_ptr cinfo, int pool_id, boolean pre_zero,
00554                    JDIMENSION blocksperrow, JDIMENSION numrows,
00555                    JDIMENSION maxaccess)
00556 /* Request a virtual 2-D coefficient-block array */
00557 {
00558   my_mem_ptr mem = (my_mem_ptr) cinfo->mem;
00559   jvirt_barray_ptr result;
00560 
00561   /* Only IMAGE-lifetime virtual arrays are currently supported */
00562   if (pool_id != JPOOL_IMAGE)
00563     ERREXIT1(cinfo, JERR_BAD_POOL_ID, pool_id);  /* safety check */
00564 
00565   /* get control block */
00566   result = (jvirt_barray_ptr) alloc_small(cinfo, pool_id,
00567                                      SIZEOF(struct jvirt_barray_control));
00568 
00569   result->mem_buffer = NULL;       /* marks array not yet realized */
00570   result->rows_in_array = numrows;
00571   result->blocksperrow = blocksperrow;
00572   result->maxaccess = maxaccess;
00573   result->pre_zero = pre_zero;
00574   result->b_s_open = FALSE; /* no associated backing-store object */
00575   result->next = mem->virt_barray_list; /* add to list of virtual arrays */
00576   mem->virt_barray_list = result;
00577 
00578   return result;
00579 }
00580 
00581 
00582 METHODDEF(void)
00583 realize_virt_arrays (j_common_ptr cinfo)
00584 /* Allocate the in-memory buffers for any unrealized virtual arrays */
00585 {
00586   my_mem_ptr mem = (my_mem_ptr) cinfo->mem;
00587   long space_per_minheight, maximum_space, avail_mem;
00588   long minheights, max_minheights;
00589   jvirt_sarray_ptr sptr;
00590   jvirt_barray_ptr bptr;
00591 
00592   /* Compute the minimum space needed (maxaccess rows in each buffer)
00593    * and the maximum space needed (full image height in each buffer).
00594    * These may be of use to the system-dependent jpeg_mem_available routine.
00595    */
00596   space_per_minheight = 0;
00597   maximum_space = 0;
00598   for (sptr = mem->virt_sarray_list; sptr != NULL; sptr = sptr->next) {
00599     if (sptr->mem_buffer == NULL) { /* if not realized yet */
00600       space_per_minheight += (long) sptr->maxaccess *
00601                           (long) sptr->samplesperrow * SIZEOF(JSAMPLE);
00602       maximum_space += (long) sptr->rows_in_array *
00603                      (long) sptr->samplesperrow * SIZEOF(JSAMPLE);
00604     }
00605   }
00606   for (bptr = mem->virt_barray_list; bptr != NULL; bptr = bptr->next) {
00607     if (bptr->mem_buffer == NULL) { /* if not realized yet */
00608       space_per_minheight += (long) bptr->maxaccess *
00609                           (long) bptr->blocksperrow * SIZEOF(JBLOCK);
00610       maximum_space += (long) bptr->rows_in_array *
00611                      (long) bptr->blocksperrow * SIZEOF(JBLOCK);
00612     }
00613   }
00614 
00615   if (space_per_minheight <= 0)
00616     return;                 /* no unrealized arrays, no work */
00617 
00618   /* Determine amount of memory to actually use; this is system-dependent. */
00619   avail_mem = jpeg_mem_available(cinfo, space_per_minheight, maximum_space,
00620                              mem->total_space_allocated);
00621 
00622   /* If the maximum space needed is available, make all the buffers full
00623    * height; otherwise parcel it out with the same number of minheights
00624    * in each buffer.
00625    */
00626   if (avail_mem >= maximum_space)
00627     max_minheights = 1000000000L;
00628   else {
00629     max_minheights = avail_mem / space_per_minheight;
00630     /* If there doesn't seem to be enough space, try to get the minimum
00631      * anyway.  This allows a "stub" implementation of jpeg_mem_available().
00632      */
00633     if (max_minheights <= 0)
00634       max_minheights = 1;
00635   }
00636 
00637   /* Allocate the in-memory buffers and initialize backing store as needed. */
00638 
00639   for (sptr = mem->virt_sarray_list; sptr != NULL; sptr = sptr->next) {
00640     if (sptr->mem_buffer == NULL) { /* if not realized yet */
00641       minheights = ((long) sptr->rows_in_array - 1L) / sptr->maxaccess + 1L;
00642       if (minheights <= max_minheights) {
00643        /* This buffer fits in memory */
00644        sptr->rows_in_mem = sptr->rows_in_array;
00645       } else {
00646        /* It doesn't fit in memory, create backing store. */
00647        sptr->rows_in_mem = (JDIMENSION) (max_minheights * sptr->maxaccess);
00648        jpeg_open_backing_store(cinfo, & sptr->b_s_info,
00649                             (long) sptr->rows_in_array *
00650                             (long) sptr->samplesperrow *
00651                             (long) SIZEOF(JSAMPLE));
00652        sptr->b_s_open = TRUE;
00653       }
00654       sptr->mem_buffer = alloc_sarray(cinfo, JPOOL_IMAGE,
00655                                   sptr->samplesperrow, sptr->rows_in_mem);
00656       sptr->rowsperchunk = mem->last_rowsperchunk;
00657       sptr->cur_start_row = 0;
00658       sptr->first_undef_row = 0;
00659       sptr->dirty = FALSE;
00660     }
00661   }
00662 
00663   for (bptr = mem->virt_barray_list; bptr != NULL; bptr = bptr->next) {
00664     if (bptr->mem_buffer == NULL) { /* if not realized yet */
00665       minheights = ((long) bptr->rows_in_array - 1L) / bptr->maxaccess + 1L;
00666       if (minheights <= max_minheights) {
00667        /* This buffer fits in memory */
00668        bptr->rows_in_mem = bptr->rows_in_array;
00669       } else {
00670        /* It doesn't fit in memory, create backing store. */
00671        bptr->rows_in_mem = (JDIMENSION) (max_minheights * bptr->maxaccess);
00672        jpeg_open_backing_store(cinfo, & bptr->b_s_info,
00673                             (long) bptr->rows_in_array *
00674                             (long) bptr->blocksperrow *
00675                             (long) SIZEOF(JBLOCK));
00676        bptr->b_s_open = TRUE;
00677       }
00678       bptr->mem_buffer = alloc_barray(cinfo, JPOOL_IMAGE,
00679                                   bptr->blocksperrow, bptr->rows_in_mem);
00680       bptr->rowsperchunk = mem->last_rowsperchunk;
00681       bptr->cur_start_row = 0;
00682       bptr->first_undef_row = 0;
00683       bptr->dirty = FALSE;
00684     }
00685   }
00686 }
00687 
00688 
00689 LOCAL(void)
00690 do_sarray_io (j_common_ptr cinfo, jvirt_sarray_ptr ptr, boolean writing)
00691 /* Do backing store read or write of a virtual sample array */
00692 {
00693   long bytesperrow, file_offset, byte_count, rows, thisrow, i;
00694 
00695   bytesperrow = (long) ptr->samplesperrow * SIZEOF(JSAMPLE);
00696   file_offset = ptr->cur_start_row * bytesperrow;
00697   /* Loop to read or write each allocation chunk in mem_buffer */
00698   for (i = 0; i < (long) ptr->rows_in_mem; i += ptr->rowsperchunk) {
00699     /* One chunk, but check for short chunk at end of buffer */
00700     rows = MIN((long) ptr->rowsperchunk, (long) ptr->rows_in_mem - i);
00701     /* Transfer no more than is currently defined */
00702     thisrow = (long) ptr->cur_start_row + i;
00703     rows = MIN(rows, (long) ptr->first_undef_row - thisrow);
00704     /* Transfer no more than fits in file */
00705     rows = MIN(rows, (long) ptr->rows_in_array - thisrow);
00706     if (rows <= 0)          /* this chunk might be past end of file! */
00707       break;
00708     byte_count = rows * bytesperrow;
00709     if (writing)
00710       (*ptr->b_s_info.write_backing_store) (cinfo, & ptr->b_s_info,
00711                                        (void FAR *) ptr->mem_buffer[i],
00712                                        file_offset, byte_count);
00713     else
00714       (*ptr->b_s_info.read_backing_store) (cinfo, & ptr->b_s_info,
00715                                       (void FAR *) ptr->mem_buffer[i],
00716                                       file_offset, byte_count);
00717     file_offset += byte_count;
00718   }
00719 }
00720 
00721 
00722 LOCAL(void)
00723 do_barray_io (j_common_ptr cinfo, jvirt_barray_ptr ptr, boolean writing)
00724 /* Do backing store read or write of a virtual coefficient-block array */
00725 {
00726   long bytesperrow, file_offset, byte_count, rows, thisrow, i;
00727 
00728   bytesperrow = (long) ptr->blocksperrow * SIZEOF(JBLOCK);
00729   file_offset = ptr->cur_start_row * bytesperrow;
00730   /* Loop to read or write each allocation chunk in mem_buffer */
00731   for (i = 0; i < (long) ptr->rows_in_mem; i += ptr->rowsperchunk) {
00732     /* One chunk, but check for short chunk at end of buffer */
00733     rows = MIN((long) ptr->rowsperchunk, (long) ptr->rows_in_mem - i);
00734     /* Transfer no more than is currently defined */
00735     thisrow = (long) ptr->cur_start_row + i;
00736     rows = MIN(rows, (long) ptr->first_undef_row - thisrow);
00737     /* Transfer no more than fits in file */
00738     rows = MIN(rows, (long) ptr->rows_in_array - thisrow);
00739     if (rows <= 0)          /* this chunk might be past end of file! */
00740       break;
00741     byte_count = rows * bytesperrow;
00742     if (writing)
00743       (*ptr->b_s_info.write_backing_store) (cinfo, & ptr->b_s_info,
00744                                        (void FAR *) ptr->mem_buffer[i],
00745                                        file_offset, byte_count);
00746     else
00747       (*ptr->b_s_info.read_backing_store) (cinfo, & ptr->b_s_info,
00748                                       (void FAR *) ptr->mem_buffer[i],
00749                                       file_offset, byte_count);
00750     file_offset += byte_count;
00751   }
00752 }
00753 
00754 
00755 METHODDEF(JSAMPARRAY)
00756 access_virt_sarray (j_common_ptr cinfo, jvirt_sarray_ptr ptr,
00757                   JDIMENSION start_row, JDIMENSION num_rows,
00758                   boolean writable)
00759 /* Access the part of a virtual sample array starting at start_row */
00760 /* and extending for num_rows rows.  writable is true if  */
00761 /* caller intends to modify the accessed area. */
00762 {
00763   JDIMENSION end_row = start_row + num_rows;
00764   JDIMENSION undef_row;
00765 
00766   /* debugging check */
00767   if (end_row > ptr->rows_in_array || num_rows > ptr->maxaccess ||
00768       ptr->mem_buffer == NULL)
00769     ERREXIT(cinfo, JERR_BAD_VIRTUAL_ACCESS);
00770 
00771   /* Make the desired part of the virtual array accessible */
00772   if (start_row < ptr->cur_start_row ||
00773       end_row > ptr->cur_start_row+ptr->rows_in_mem) {
00774     if (! ptr->b_s_open)
00775       ERREXIT(cinfo, JERR_VIRTUAL_BUG);
00776     /* Flush old buffer contents if necessary */
00777     if (ptr->dirty) {
00778       do_sarray_io(cinfo, ptr, TRUE);
00779       ptr->dirty = FALSE;
00780     }
00781     /* Decide what part of virtual array to access.
00782      * Algorithm: if target address > current window, assume forward scan,
00783      * load starting at target address.  If target address < current window,
00784      * assume backward scan, load so that target area is top of window.
00785      * Note that when switching from forward write to forward read, will have
00786      * start_row = 0, so the limiting case applies and we load from 0 anyway.
00787      */
00788     if (start_row > ptr->cur_start_row) {
00789       ptr->cur_start_row = start_row;
00790     } else {
00791       /* use long arithmetic here to avoid overflow & unsigned problems */
00792       long ltemp;
00793 
00794       ltemp = (long) end_row - (long) ptr->rows_in_mem;
00795       if (ltemp < 0)
00796        ltemp = 0;           /* don't fall off front end of file */
00797       ptr->cur_start_row = (JDIMENSION) ltemp;
00798     }
00799     /* Read in the selected part of the array.
00800      * During the initial write pass, we will do no actual read
00801      * because the selected part is all undefined.
00802      */
00803     do_sarray_io(cinfo, ptr, FALSE);
00804   }
00805   /* Ensure the accessed part of the array is defined; prezero if needed.
00806    * To improve locality of access, we only prezero the part of the array
00807    * that the caller is about to access, not the entire in-memory array.
00808    */
00809   if (ptr->first_undef_row < end_row) {
00810     if (ptr->first_undef_row < start_row) {
00811       if (writable)         /* writer skipped over a section of array */
00812        ERREXIT(cinfo, JERR_BAD_VIRTUAL_ACCESS);
00813       undef_row = start_row;       /* but reader is allowed to read ahead */
00814     } else {
00815       undef_row = ptr->first_undef_row;
00816     }
00817     if (writable)
00818       ptr->first_undef_row = end_row;
00819     if (ptr->pre_zero) {
00820       size_t bytesperrow = (size_t) ptr->samplesperrow * SIZEOF(JSAMPLE);
00821       undef_row -= ptr->cur_start_row; /* make indexes relative to buffer */
00822       end_row -= ptr->cur_start_row;
00823       while (undef_row < end_row) {
00824        jzero_far((void FAR *) ptr->mem_buffer[undef_row], bytesperrow);
00825        undef_row++;
00826       }
00827     } else {
00828       if (! writable)              /* reader looking at undefined data */
00829        ERREXIT(cinfo, JERR_BAD_VIRTUAL_ACCESS);
00830     }
00831   }
00832   /* Flag the buffer dirty if caller will write in it */
00833   if (writable)
00834     ptr->dirty = TRUE;
00835   /* Return address of proper part of the buffer */
00836   return ptr->mem_buffer + (start_row - ptr->cur_start_row);
00837 }
00838 
00839 
00840 METHODDEF(JBLOCKARRAY)
00841 access_virt_barray (j_common_ptr cinfo, jvirt_barray_ptr ptr,
00842                   JDIMENSION start_row, JDIMENSION num_rows,
00843                   boolean writable)
00844 /* Access the part of a virtual block array starting at start_row */
00845 /* and extending for num_rows rows.  writable is true if  */
00846 /* caller intends to modify the accessed area. */
00847 {
00848   JDIMENSION end_row = start_row + num_rows;
00849   JDIMENSION undef_row;
00850 
00851   /* debugging check */
00852   if (end_row > ptr->rows_in_array || num_rows > ptr->maxaccess ||
00853       ptr->mem_buffer == NULL)
00854     ERREXIT(cinfo, JERR_BAD_VIRTUAL_ACCESS);
00855 
00856   /* Make the desired part of the virtual array accessible */
00857   if (start_row < ptr->cur_start_row ||
00858       end_row > ptr->cur_start_row+ptr->rows_in_mem) {
00859     if (! ptr->b_s_open)
00860       ERREXIT(cinfo, JERR_VIRTUAL_BUG);
00861     /* Flush old buffer contents if necessary */
00862     if (ptr->dirty) {
00863       do_barray_io(cinfo, ptr, TRUE);
00864       ptr->dirty = FALSE;
00865     }
00866     /* Decide what part of virtual array to access.
00867      * Algorithm: if target address > current window, assume forward scan,
00868      * load starting at target address.  If target address < current window,
00869      * assume backward scan, load so that target area is top of window.
00870      * Note that when switching from forward write to forward read, will have
00871      * start_row = 0, so the limiting case applies and we load from 0 anyway.
00872      */
00873     if (start_row > ptr->cur_start_row) {
00874       ptr->cur_start_row = start_row;
00875     } else {
00876       /* use long arithmetic here to avoid overflow & unsigned problems */
00877       long ltemp;
00878 
00879       ltemp = (long) end_row - (long) ptr->rows_in_mem;
00880       if (ltemp < 0)
00881        ltemp = 0;           /* don't fall off front end of file */
00882       ptr->cur_start_row = (JDIMENSION) ltemp;
00883     }
00884     /* Read in the selected part of the array.
00885      * During the initial write pass, we will do no actual read
00886      * because the selected part is all undefined.
00887      */
00888     do_barray_io(cinfo, ptr, FALSE);
00889   }
00890   /* Ensure the accessed part of the array is defined; prezero if needed.
00891    * To improve locality of access, we only prezero the part of the array
00892    * that the caller is about to access, not the entire in-memory array.
00893    */
00894   if (ptr->first_undef_row < end_row) {
00895     if (ptr->first_undef_row < start_row) {
00896       if (writable)         /* writer skipped over a section of array */
00897        ERREXIT(cinfo, JERR_BAD_VIRTUAL_ACCESS);
00898       undef_row = start_row;       /* but reader is allowed to read ahead */
00899     } else {
00900       undef_row = ptr->first_undef_row;
00901     }
00902     if (writable)
00903       ptr->first_undef_row = end_row;
00904     if (ptr->pre_zero) {
00905       size_t bytesperrow = (size_t) ptr->blocksperrow * SIZEOF(JBLOCK);
00906       undef_row -= ptr->cur_start_row; /* make indexes relative to buffer */
00907       end_row -= ptr->cur_start_row;
00908       while (undef_row < end_row) {
00909        jzero_far((void FAR *) ptr->mem_buffer[undef_row], bytesperrow);
00910        undef_row++;
00911       }
00912     } else {
00913       if (! writable)              /* reader looking at undefined data */
00914        ERREXIT(cinfo, JERR_BAD_VIRTUAL_ACCESS);
00915     }
00916   }
00917   /* Flag the buffer dirty if caller will write in it */
00918   if (writable)
00919     ptr->dirty = TRUE;
00920   /* Return address of proper part of the buffer */
00921   return ptr->mem_buffer + (start_row - ptr->cur_start_row);
00922 }
00923 
00924 
00925 /*
00926  * Release all objects belonging to a specified pool.
00927  */
00928 
00929 METHODDEF(void)
00930 free_pool (j_common_ptr cinfo, int pool_id)
00931 {
00932   my_mem_ptr mem = (my_mem_ptr) cinfo->mem;
00933   small_pool_ptr shdr_ptr;
00934   large_pool_ptr lhdr_ptr;
00935   size_t space_freed;
00936 
00937   if (pool_id < 0 || pool_id >= JPOOL_NUMPOOLS)
00938     ERREXIT1(cinfo, JERR_BAD_POOL_ID, pool_id);  /* safety check */
00939 
00940 #ifdef MEM_STATS
00941   if (cinfo->err->trace_level > 1)
00942     print_mem_stats(cinfo, pool_id); /* print pool's memory usage statistics */
00943 #endif
00944 
00945   /* If freeing IMAGE pool, close any virtual arrays first */
00946   if (pool_id == JPOOL_IMAGE) {
00947     jvirt_sarray_ptr sptr;
00948     jvirt_barray_ptr bptr;
00949 
00950     for (sptr = mem->virt_sarray_list; sptr != NULL; sptr = sptr->next) {
00951       if (sptr->b_s_open) { /* there may be no backing store */
00952        sptr->b_s_open = FALSE;     /* prevent recursive close if error */
00953        (*sptr->b_s_info.close_backing_store) (cinfo, & sptr->b_s_info);
00954       }
00955     }
00956     mem->virt_sarray_list = NULL;
00957     for (bptr = mem->virt_barray_list; bptr != NULL; bptr = bptr->next) {
00958       if (bptr->b_s_open) { /* there may be no backing store */
00959        bptr->b_s_open = FALSE;     /* prevent recursive close if error */
00960        (*bptr->b_s_info.close_backing_store) (cinfo, & bptr->b_s_info);
00961       }
00962     }
00963     mem->virt_barray_list = NULL;
00964   }
00965 
00966   /* Release large objects */
00967   lhdr_ptr = mem->large_list[pool_id];
00968   mem->large_list[pool_id] = NULL;
00969 
00970   while (lhdr_ptr != NULL) {
00971     large_pool_ptr next_lhdr_ptr = lhdr_ptr->hdr.next;
00972     space_freed = lhdr_ptr->hdr.bytes_used +
00973                 lhdr_ptr->hdr.bytes_left +
00974                 SIZEOF(large_pool_hdr);
00975     jpeg_free_large(cinfo, (void FAR *) lhdr_ptr, space_freed);
00976     mem->total_space_allocated -= space_freed;
00977     lhdr_ptr = next_lhdr_ptr;
00978   }
00979 
00980   /* Release small objects */
00981   shdr_ptr = mem->small_list[pool_id];
00982   mem->small_list[pool_id] = NULL;
00983 
00984   while (shdr_ptr != NULL) {
00985     small_pool_ptr next_shdr_ptr = shdr_ptr->hdr.next;
00986     space_freed = shdr_ptr->hdr.bytes_used +
00987                 shdr_ptr->hdr.bytes_left +
00988                 SIZEOF(small_pool_hdr);
00989     jpeg_free_small(cinfo, (void *) shdr_ptr, space_freed);
00990     mem->total_space_allocated -= space_freed;
00991     shdr_ptr = next_shdr_ptr;
00992   }
00993 }
00994 
00995 
00996 /*
00997  * Close up shop entirely.
00998  * Note that this cannot be called unless cinfo->mem is non-NULL.
00999  */
01000 
01001 METHODDEF(void)
01002 self_destruct (j_common_ptr cinfo)
01003 {
01004   int pool;
01005 
01006   /* Close all backing store, release all memory.
01007    * Releasing pools in reverse order might help avoid fragmentation
01008    * with some (brain-damaged) malloc libraries.
01009    */
01010   for (pool = JPOOL_NUMPOOLS-1; pool >= JPOOL_PERMANENT; pool--) {
01011     free_pool(cinfo, pool);
01012   }
01013 
01014   /* Release the memory manager control block too. */
01015   jpeg_free_small(cinfo, (void *) cinfo->mem, SIZEOF(my_memory_mgr));
01016   cinfo->mem = NULL;        /* ensures I will be called only once */
01017 
01018   jpeg_mem_term(cinfo);            /* system-dependent cleanup */
01019 }
01020 
01021 
01022 /*
01023  * Memory manager initialization.
01024  * When this is called, only the error manager pointer is valid in cinfo!
01025  */
01026 
01027 GLOBAL(void)
01028 jinit_memory_mgr (j_common_ptr cinfo)
01029 {
01030   my_mem_ptr mem;
01031   long max_to_use;
01032   int pool;
01033   size_t test_mac;
01034 
01035   cinfo->mem = NULL;        /* for safety if init fails */
01036 
01037   /* Check for configuration errors.
01038    * SIZEOF(ALIGN_TYPE) should be a power of 2; otherwise, it probably
01039    * doesn't reflect any real hardware alignment requirement.
01040    * The test is a little tricky: for X>0, X and X-1 have no one-bits
01041    * in common if and only if X is a power of 2, ie has only one one-bit.
01042    * Some compilers may give an "unreachable code" warning here; ignore it.
01043    */
01044   if ((SIZEOF(ALIGN_TYPE) & (SIZEOF(ALIGN_TYPE)-1)) != 0)
01045     ERREXIT(cinfo, JERR_BAD_ALIGN_TYPE);
01046   /* MAX_ALLOC_CHUNK must be representable as type size_t, and must be
01047    * a multiple of SIZEOF(ALIGN_TYPE).
01048    * Again, an "unreachable code" warning may be ignored here.
01049    * But a "constant too large" warning means you need to fix MAX_ALLOC_CHUNK.
01050    */
01051   test_mac = (size_t) MAX_ALLOC_CHUNK;
01052   if ((long) test_mac != MAX_ALLOC_CHUNK ||
01053       (MAX_ALLOC_CHUNK % SIZEOF(ALIGN_TYPE)) != 0)
01054     ERREXIT(cinfo, JERR_BAD_ALLOC_CHUNK);
01055 
01056   max_to_use = jpeg_mem_init(cinfo); /* system-dependent initialization */
01057 
01058   /* Attempt to allocate memory manager's control block */
01059   mem = (my_mem_ptr) jpeg_get_small(cinfo, SIZEOF(my_memory_mgr));
01060 
01061   if (mem == NULL) {
01062     jpeg_mem_term(cinfo);   /* system-dependent cleanup */
01063     ERREXIT1(cinfo, JERR_OUT_OF_MEMORY, 0);
01064   }
01065 
01066   /* OK, fill in the method pointers */
01067   mem->pub.alloc_small = alloc_small;
01068   mem->pub.alloc_large = alloc_large;
01069   mem->pub.alloc_sarray = alloc_sarray;
01070   mem->pub.alloc_barray = alloc_barray;
01071   mem->pub.request_virt_sarray = request_virt_sarray;
01072   mem->pub.request_virt_barray = request_virt_barray;
01073   mem->pub.realize_virt_arrays = realize_virt_arrays;
01074   mem->pub.access_virt_sarray = access_virt_sarray;
01075   mem->pub.access_virt_barray = access_virt_barray;
01076   mem->pub.free_pool = free_pool;
01077   mem->pub.self_destruct = self_destruct;
01078 
01079   /* Make MAX_ALLOC_CHUNK accessible to other modules */
01080   mem->pub.max_alloc_chunk = MAX_ALLOC_CHUNK;
01081 
01082   /* Initialize working state */
01083   mem->pub.max_memory_to_use = max_to_use;
01084 
01085   for (pool = JPOOL_NUMPOOLS-1; pool >= JPOOL_PERMANENT; pool--) {
01086     mem->small_list[pool] = NULL;
01087     mem->large_list[pool] = NULL;
01088   }
01089   mem->virt_sarray_list = NULL;
01090   mem->virt_barray_list = NULL;
01091 
01092   mem->total_space_allocated = SIZEOF(my_memory_mgr);
01093 
01094   /* Declare ourselves open for business */
01095   cinfo->mem = & mem->pub;
01096 
01097   /* Check for an environment variable JPEGMEM; if found, override the
01098    * default max_memory setting from jpeg_mem_init.  Note that the
01099    * surrounding application may again override this value.
01100    * If your system doesn't support getenv(), define NO_GETENV to disable
01101    * this feature.
01102    */
01103 #ifndef NO_GETENV
01104   { char * memenv;
01105 
01106     if ((memenv = getenv("JPEGMEM")) != NULL) {
01107       char ch = 'x';
01108 
01109       if (sscanf(memenv, "%ld%c", &max_to_use, &ch) > 0) {
01110        if (ch == 'm' || ch == 'M')
01111          max_to_use *= 1000L;
01112        mem->pub.max_memory_to_use = max_to_use * 1000L;
01113       }
01114     }
01115   }
01116 #endif
01117 
01118 }