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 /*

  * jmemmgr.c

  *

  * Copyright (C) 1991-1997, Thomas G. Lane.

  * This file is part of the Independent JPEG Group's software.

  * For conditions of distribution and use, see the accompanying README file.

  *

  * This file contains the JPEG system-independent memory management

  * routines.  This code is usable across a wide variety of machines; most

  * of the system dependencies have been isolated in a separate file.

  * The major functions provided here are:

  *   * pool-based allocation and freeing of memory;

  *   * policy decisions about how to divide available memory among the

  *     virtual arrays;

  *   * control logic for swapping virtual arrays between main memory and

  *     backing storage.

  * The separate system-dependent file provides the actual backing-storage

  * access code, and it contains the policy decision about how much total

  * main memory to use.

  * This file is system-dependent in the sense that some of its functions

  * are unnecessary in some systems.  For example, if there is enough virtual

  * memory so that backing storage will never be used, much of the virtual

  * array control logic could be removed.  (Of course, if you have that much

  * memory then you shouldn't care about a little bit of unused code...)

  */

 #define JPEG_INTERNALS

 #define AM_MEMORY_MANAGER	/* we define jvirt_Xarray_control structs */

 #include "jinclude.h"

 #include "jpeglib.h"

 #include "jmemsys.h"		/* import the system-dependent declarations */

 #ifndef NO_GETENV

 #ifndef HAVE_STDLIB_H		/* <stdlib.h> should declare getenv() */

 extern char * getenv JPP((const char * name));

 #endif

 #endif

 LOCAL(size_t)

 round_up_pow2 (size_t a, size_t b)

 /* a rounded up to the next multiple of b, i.e. ceil(a/b)*b */

 /* Assumes a >= 0, b > 0, and b is a power of 2 */

 {

   return ((a + b - 1) & (~(b - 1)));

 }

 /*

  * Some important notes:

  *   The allocation routines provided here must never return NULL.

  *   They should exit to error_exit if unsuccessful.

  *

  *   It's not a good idea to try to merge the sarray and barray routines,

  *   even though they are textually almost the same, because samples are

  *   usually stored as bytes while coefficients are shorts or ints.  Thus,

  *   in machines where byte pointers have a different representation from

  *   word pointers, the resulting machine code could not be the same.

  */

 /*

  * Many machines require storage alignment: longs must start on 4-byte

  * boundaries, doubles on 8-byte boundaries, etc.  On such machines, malloc()

  * always returns pointers that are multiples of the worst-case alignment

  * requirement, and we had better do so too.

  * There isn't any really portable way to determine the worst-case alignment

  * requirement.  This module assumes that the alignment requirement is

  * multiples of ALIGN_SIZE.

  * By default, we define ALIGN_SIZE as sizeof(double).  This is necessary on some

  * workstations (where doubles really do need 8-byte alignment) and will work

  * fine on nearly everything.  If your machine has lesser alignment needs,

  * you can save a few bytes by making ALIGN_SIZE smaller.

  * The only place I know of where this will NOT work is certain Macintosh

  * 680x0 compilers that define double as a 10-byte IEEE extended float.

  * Doing 10-byte alignment is counterproductive because longwords won't be

  * aligned well.  Put "#define ALIGN_SIZE 4" in jconfig.h if you have

  * such a compiler.

  */

 #ifndef ALIGN_SIZE		/* so can override from jconfig.h */

 #ifndef WITH_SIMD

 #define ALIGN_SIZE  SIZEOF(double)

 #else

 #define ALIGN_SIZE  16 /* Most SIMD implementations require this */

 #endif

 #endif

 /*

  * We allocate objects from "pools", where each pool is gotten with a single

  * request to jpeg_get_small() or jpeg_get_large().  There is no per-object

  * overhead within a pool, except for alignment padding.  Each pool has a

  * header with a link to the next pool of the same class.

  * Small and large pool headers are identical except that the latter's

  * link pointer must be FAR on 80x86 machines.

  */

 typedef struct small_pool_struct * small_pool_ptr;

 typedef struct small_pool_struct {

   small_pool_ptr next;	/* next in list of pools */

   size_t bytes_used;		/* how many bytes already used within pool */

   size_t bytes_left;		/* bytes still available in this pool */

 } small_pool_hdr;

 typedef struct large_pool_struct FAR * large_pool_ptr;

 typedef struct large_pool_struct {

   large_pool_ptr next;	/* next in list of pools */

   size_t bytes_used;		/* how many bytes already used within pool */

   size_t bytes_left;		/* bytes still available in this pool */

 } large_pool_hdr;

 /*

  * Here is the full definition of a memory manager object.

  */

 typedef struct {

   struct jpeg_memory_mgr pub;	/* public fields */

   /* Each pool identifier (lifetime class) names a linked list of pools. */

   small_pool_ptr small_list[JPOOL_NUMPOOLS];

   large_pool_ptr large_list[JPOOL_NUMPOOLS];

   /* Since we only have one lifetime class of virtual arrays, only one

    * linked list is necessary (for each datatype).  Note that the virtual

    * array control blocks being linked together are actually stored somewhere

    * in the small-pool list.

    */

   jvirt_sarray_ptr virt_sarray_list;

   jvirt_barray_ptr virt_barray_list;

   /* This counts total space obtained from jpeg_get_small/large */

   size_t total_space_allocated;

   /* alloc_sarray and alloc_barray set this value for use by virtual

    * array routines.

    */

   JDIMENSION last_rowsperchunk;	/* from most recent alloc_sarray/barray */

 } my_memory_mgr;

 typedef my_memory_mgr * my_mem_ptr;

 /*

  * The control blocks for virtual arrays.

  * Note that these blocks are allocated in the "small" pool area.

  * System-dependent info for the associated backing store (if any) is hidden

  * inside the backing_store_info struct.

  */

 struct jvirt_sarray_control {

   JSAMPARRAY mem_buffer;	/* => the in-memory buffer */

   JDIMENSION rows_in_array;	/* total virtual array height */

   JDIMENSION samplesperrow;	/* width of array (and of memory buffer) */

   JDIMENSION maxaccess;		/* max rows accessed by access_virt_sarray */

   JDIMENSION rows_in_mem;	/* height of memory buffer */

   JDIMENSION rowsperchunk;	/* allocation chunk size in mem_buffer */

   JDIMENSION cur_start_row;	/* first logical row # in the buffer */

   JDIMENSION first_undef_row;	/* row # of first uninitialized row */

   boolean pre_zero;		/* pre-zero mode requested? */

   boolean dirty;		/* do current buffer contents need written? */

   boolean b_s_open;		/* is backing-store data valid? */

   jvirt_sarray_ptr next;	/* link to next virtual sarray control block */

   backing_store_info b_s_info;	/* System-dependent control info */

 };

 struct jvirt_barray_control {

   JBLOCKARRAY mem_buffer;	/* => the in-memory buffer */

   JDIMENSION rows_in_array;	/* total virtual array height */

   JDIMENSION blocksperrow;	/* width of array (and of memory buffer) */

   JDIMENSION maxaccess;		/* max rows accessed by access_virt_barray */

   JDIMENSION rows_in_mem;	/* height of memory buffer */

   JDIMENSION rowsperchunk;	/* allocation chunk size in mem_buffer */

   JDIMENSION cur_start_row;	/* first logical row # in the buffer */

   JDIMENSION first_undef_row;	/* row # of first uninitialized row */

   boolean pre_zero;		/* pre-zero mode requested? */

   boolean dirty;		/* do current buffer contents need written? */

   boolean b_s_open;		/* is backing-store data valid? */

   jvirt_barray_ptr next;	/* link to next virtual barray control block */

   backing_store_info b_s_info;	/* System-dependent control info */

 };

 #ifdef MEM_STATS		/* optional extra stuff for statistics */

 LOCAL(void)

 print_mem_stats (j_common_ptr cinfo, int pool_id)

 {

   my_mem_ptr mem = (my_mem_ptr) cinfo->mem;

   small_pool_ptr shdr_ptr;

   large_pool_ptr lhdr_ptr;

   /* Since this is only a debugging stub, we can cheat a little by using

    * fprintf directly rather than going through the trace message code.

    * This is helpful because message parm array can't handle longs.

    */

   fprintf(stderr, "Freeing pool %d, total space = %ld\n",

 	  pool_id, mem->total_space_allocated);

   for (lhdr_ptr = mem->large_list[pool_id]; lhdr_ptr != NULL;

        lhdr_ptr = lhdr_ptr->next) {

     fprintf(stderr, "  Large chunk used %ld\n",

 	    (long) lhdr_ptr->bytes_used);

   }

   for (shdr_ptr = mem->small_list[pool_id]; shdr_ptr != NULL;

        shdr_ptr = shdr_ptr->next) {

     fprintf(stderr, "  Small chunk used %ld free %ld\n",

 	    (long) shdr_ptr->bytes_used,

 	    (long) shdr_ptr->bytes_left);

   }

 }

 #endif /* MEM_STATS */

 LOCAL(void)

 out_of_memory (j_common_ptr cinfo, int which)

 /* Report an out-of-memory error and stop execution */

 /* If we compiled MEM_STATS support, report alloc requests before dying */

 {

 #ifdef MEM_STATS

   cinfo->err->trace_level = 2;	/* force self_destruct to report stats */

 #endif

   ERREXIT1(cinfo, JERR_OUT_OF_MEMORY, which);

 }

 /*

  * Allocation of "small" objects.

  *

  * For these, we use pooled storage.  When a new pool must be created,

  * we try to get enough space for the current request plus a "slop" factor,

  * where the slop will be the amount of leftover space in the new pool.

  * The speed vs. space tradeoff is largely determined by the slop values.

  * A different slop value is provided for each pool class (lifetime),

  * and we also distinguish the first pool of a class from later ones.

  * NOTE: the values given work fairly well on both 16- and 32-bit-int

  * machines, but may be too small if longs are 64 bits or more.

  *

  * Since we do not know what alignment malloc() gives us, we have to

  * allocate ALIGN_SIZE-1 extra space per pool to have room for alignment

  * adjustment.

  */

 static const size_t first_pool_slop[JPOOL_NUMPOOLS] = 

 {

 	1600,			/* first PERMANENT pool */

 	16000			/* first IMAGE pool */

 };

 static const size_t extra_pool_slop[JPOOL_NUMPOOLS] = 

 {

 	0,			/* additional PERMANENT pools */

 	5000			/* additional IMAGE pools */

 };

 #define MIN_SLOP  50		/* greater than 0 to avoid futile looping */

 METHODDEF(void *)

 alloc_small (j_common_ptr cinfo, int pool_id, size_t sizeofobject)

 /* Allocate a "small" object */

 {

   my_mem_ptr mem = (my_mem_ptr) cinfo->mem;

   small_pool_ptr hdr_ptr, prev_hdr_ptr;

   char * data_ptr;

   size_t min_request, slop;

   /*

    * Round up the requested size to a multiple of ALIGN_SIZE in order

    * to assure alignment for the next object allocated in the same pool

    * and so that algorithms can straddle outside the proper area up

    * to the next alignment.

    */

   sizeofobject = round_up_pow2(sizeofobject, ALIGN_SIZE);

   /* Check for unsatisfiable request (do now to ensure no overflow below) */

   if ((SIZEOF(small_pool_hdr) + sizeofobject + ALIGN_SIZE - 1) > MAX_ALLOC_CHUNK)

     out_of_memory(cinfo, 1);	/* request exceeds malloc's ability */

   /* See if space is available in any existing pool */

   if (pool_id < 0 || pool_id >= JPOOL_NUMPOOLS)

     ERREXIT1(cinfo, JERR_BAD_POOL_ID, pool_id);	/* safety check */

   prev_hdr_ptr = NULL;

   hdr_ptr = mem->small_list[pool_id];

   while (hdr_ptr != NULL) {

     if (hdr_ptr->bytes_left >= sizeofobject)

       break;			/* found pool with enough space */

     prev_hdr_ptr = hdr_ptr;

     hdr_ptr = hdr_ptr->next;

   }

   /* Time to make a new pool? */

   if (hdr_ptr == NULL) {

     /* min_request is what we need now, slop is what will be leftover */

     min_request = SIZEOF(small_pool_hdr) + sizeofobject + ALIGN_SIZE - 1;

     if (prev_hdr_ptr == NULL)	/* first pool in class? */

       slop = first_pool_slop[pool_id];

     else

       slop = extra_pool_slop[pool_id];

     /* Don't ask for more than MAX_ALLOC_CHUNK */

     if (slop > (size_t) (MAX_ALLOC_CHUNK-min_request))

       slop = (size_t) (MAX_ALLOC_CHUNK-min_request);

     /* Try to get space, if fail reduce slop and try again */

     for (;;) {

       hdr_ptr = (small_pool_ptr) jpeg_get_small(cinfo, min_request + slop);

       if (hdr_ptr != NULL)

 	break;

       slop /= 2;

       if (slop < MIN_SLOP)	/* give up when it gets real small */

 	out_of_memory(cinfo, 2); /* jpeg_get_small failed */

     }

     mem->total_space_allocated += min_request + slop;

     /* Success, initialize the new pool header and add to end of list */

     hdr_ptr->next = NULL;

     hdr_ptr->bytes_used = 0;

     hdr_ptr->bytes_left = sizeofobject + slop;

     if (prev_hdr_ptr == NULL)	/* first pool in class? */

       mem->small_list[pool_id] = hdr_ptr;

     else

       prev_hdr_ptr->next = hdr_ptr;

   }

   /* OK, allocate the object from the current pool */

   data_ptr = (char *) hdr_ptr; /* point to first data byte in pool... */

   data_ptr += SIZEOF(small_pool_hdr); /* ...by skipping the header... */

   if ((size_t)data_ptr % ALIGN_SIZE) /* ...and adjust for alignment */

     data_ptr += ALIGN_SIZE - (size_t)data_ptr % ALIGN_SIZE;

   data_ptr += hdr_ptr->bytes_used; /* point to place for object */

   hdr_ptr->bytes_used += sizeofobject;

   hdr_ptr->bytes_left -= sizeofobject;

   return (void *) data_ptr;

 }

 /*

  * Allocation of "large" objects.

  *

  * The external semantics of these are the same as "small" objects,

  * except that FAR pointers are used on 80x86.  However the pool

  * management heuristics are quite different.  We assume that each

  * request is large enough that it may as well be passed directly to

  * jpeg_get_large; the pool management just links everything together

  * so that we can free it all on demand.

  * Note: the major use of "large" objects is in JSAMPARRAY and JBLOCKARRAY

  * structures.  The routines that create these structures (see below)

  * deliberately bunch rows together to ensure a large request size.

  */

 METHODDEF(void FAR *)

 alloc_large (j_common_ptr cinfo, int pool_id, size_t sizeofobject)

 /* Allocate a "large" object */

 {

   my_mem_ptr mem = (my_mem_ptr) cinfo->mem;

   large_pool_ptr hdr_ptr;

   char FAR * data_ptr;

   /*

    * Round up the requested size to a multiple of ALIGN_SIZE so that

    * algorithms can straddle outside the proper area up to the next

    * alignment.

    */

   sizeofobject = round_up_pow2(sizeofobject, ALIGN_SIZE);

   /* Check for unsatisfiable request (do now to ensure no overflow below) */

   if ((SIZEOF(large_pool_hdr) + sizeofobject + ALIGN_SIZE - 1) > MAX_ALLOC_CHUNK)

     out_of_memory(cinfo, 3);	/* request exceeds malloc's ability */

   /* Always make a new pool */

   if (pool_id < 0 || pool_id >= JPOOL_NUMPOOLS)

     ERREXIT1(cinfo, JERR_BAD_POOL_ID, pool_id);	/* safety check */

   hdr_ptr = (large_pool_ptr) jpeg_get_large(cinfo, sizeofobject +

 					    SIZEOF(large_pool_hdr) +

 					    ALIGN_SIZE - 1);

   if (hdr_ptr == NULL)

     out_of_memory(cinfo, 4);	/* jpeg_get_large failed */

   mem->total_space_allocated += sizeofobject + SIZEOF(large_pool_hdr) + ALIGN_SIZE - 1;

   /* Success, initialize the new pool header and add to list */

   hdr_ptr->next = mem->large_list[pool_id];

   /* We maintain space counts in each pool header for statistical purposes,

    * even though they are not needed for allocation.

    */

   hdr_ptr->bytes_used = sizeofobject;

   hdr_ptr->bytes_left = 0;

   mem->large_list[pool_id] = hdr_ptr;

   data_ptr = (char *) hdr_ptr; /* point to first data byte in pool... */

   data_ptr += SIZEOF(small_pool_hdr); /* ...by skipping the header... */

   if ((size_t)data_ptr % ALIGN_SIZE) /* ...and adjust for alignment */

     data_ptr += ALIGN_SIZE - (size_t)data_ptr % ALIGN_SIZE;

   return (void FAR *) data_ptr;

 }

 /*

  * Creation of 2-D sample arrays.

  * The pointers are in near heap, the samples themselves in FAR heap.

  *

  * To minimize allocation overhead and to allow I/O of large contiguous

  * blocks, we allocate the sample rows in groups of as many rows as possible

  * without exceeding MAX_ALLOC_CHUNK total bytes per allocation request.

  * NB: the virtual array control routines, later in this file, know about

  * this chunking of rows.  The rowsperchunk value is left in the mem manager

  * object so that it can be saved away if this sarray is the workspace for

  * a virtual array.

  *

  * Since we are often upsampling with a factor 2, we align the size (not

  * the start) to 2 * ALIGN_SIZE so that the upsampling routines don't have

  * to be as careful about size.

  */

 METHODDEF(JSAMPARRAY)

 alloc_sarray (j_common_ptr cinfo, int pool_id,

 	      JDIMENSION samplesperrow, JDIMENSION numrows)

 /* Allocate a 2-D sample array */

 {

   my_mem_ptr mem = (my_mem_ptr) cinfo->mem;

   JSAMPARRAY result;

   JSAMPROW workspace;

   JDIMENSION rowsperchunk, currow, i;

   long ltemp;

   /* Make sure each row is properly aligned */

   if ((ALIGN_SIZE % SIZEOF(JSAMPLE)) != 0)

     out_of_memory(cinfo, 5);	/* safety check */

   samplesperrow = (JDIMENSION)round_up_pow2(samplesperrow, (2 * ALIGN_SIZE) / SIZEOF(JSAMPLE));

   /* Calculate max # of rows allowed in one allocation chunk */

   ltemp = (MAX_ALLOC_CHUNK-SIZEOF(large_pool_hdr)) /

 	  ((long) samplesperrow * SIZEOF(JSAMPLE));

   if (ltemp <= 0)

     ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);

   if (ltemp < (long) numrows)

     rowsperchunk = (JDIMENSION) ltemp;

   else

     rowsperchunk = numrows;

   mem->last_rowsperchunk = rowsperchunk;

   /* Get space for row pointers (small object) */

   result = (JSAMPARRAY) alloc_small(cinfo, pool_id,

 				    (size_t) (numrows * SIZEOF(JSAMPROW)));

   /* Get the rows themselves (large objects) */

   currow = 0;

   while (currow < numrows) {

     rowsperchunk = MIN(rowsperchunk, numrows - currow);

     workspace = (JSAMPROW) alloc_large(cinfo, pool_id,

 	(size_t) ((size_t) rowsperchunk * (size_t) samplesperrow

 		  * SIZEOF(JSAMPLE)));

     for (i = rowsperchunk; i > 0; i--) {

       result[currow++] = workspace;

       workspace += samplesperrow;

     }

   }

   return result;

 }

 /*

  * Creation of 2-D coefficient-block arrays.

  * This is essentially the same as the code for sample arrays, above.

  */

 METHODDEF(JBLOCKARRAY)

 alloc_barray (j_common_ptr cinfo, int pool_id,

 	      JDIMENSION blocksperrow, JDIMENSION numrows)

 /* Allocate a 2-D coefficient-block array */

 {

   my_mem_ptr mem = (my_mem_ptr) cinfo->mem;

   JBLOCKARRAY result;

   JBLOCKROW workspace;

   JDIMENSION rowsperchunk, currow, i;

   long ltemp;

   /* Make sure each row is properly aligned */

   if ((SIZEOF(JBLOCK) % ALIGN_SIZE) != 0)

     out_of_memory(cinfo, 6);	/* safety check */

   /* Calculate max # of rows allowed in one allocation chunk */

   ltemp = (MAX_ALLOC_CHUNK-SIZEOF(large_pool_hdr)) /

 	  ((long) blocksperrow * SIZEOF(JBLOCK));

   if (ltemp <= 0)

     ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);

   if (ltemp < (long) numrows)

     rowsperchunk = (JDIMENSION) ltemp;

   else

     rowsperchunk = numrows;

   mem->last_rowsperchunk = rowsperchunk;

   /* Get space for row pointers (small object) */

   result = (JBLOCKARRAY) alloc_small(cinfo, pool_id,

 				     (size_t) (numrows * SIZEOF(JBLOCKROW)));

   /* Get the rows themselves (large objects) */

   currow = 0;

   while (currow < numrows) {

     rowsperchunk = MIN(rowsperchunk, numrows - currow);

     workspace = (JBLOCKROW) alloc_large(cinfo, pool_id,

 	(size_t) ((size_t) rowsperchunk * (size_t) blocksperrow

 		  * SIZEOF(JBLOCK)));

     for (i = rowsperchunk; i > 0; i--) {

       result[currow++] = workspace;

       workspace += blocksperrow;

     }

   }

   return result;

 }

 /*

  * About virtual array management:

  *

  * The above "normal" array routines are only used to allocate strip buffers

  * (as wide as the image, but just a few rows high).  Full-image-sized buffers

  * are handled as "virtual" arrays.  The array is still accessed a strip at a

  * time, but the memory manager must save the whole array for repeated

  * accesses.  The intended implementation is that there is a strip buffer in

  * memory (as high as is possible given the desired memory limit), plus a

  * backing file that holds the rest of the array.

  *

  * The request_virt_array routines are told the total size of the image and

  * the maximum number of rows that will be accessed at once.  The in-memory

  * buffer must be at least as large as the maxaccess value.

  *

  * The request routines create control blocks but not the in-memory buffers.

  * That is postponed until realize_virt_arrays is called.  At that time the

  * total amount of space needed is known (approximately, anyway), so free

  * memory can be divided up fairly.

  *

  * The access_virt_array routines are responsible for making a specific strip

  * area accessible (after reading or writing the backing file, if necessary).

  * Note that the access routines are told whether the caller intends to modify

  * the accessed strip; during a read-only pass this saves having to rewrite

  * data to disk.  The access routines are also responsible for pre-zeroing

  * any newly accessed rows, if pre-zeroing was requested.

  *

  * In current usage, the access requests are usually for nonoverlapping

  * strips; that is, successive access start_row numbers differ by exactly

  * num_rows = maxaccess.  This means we can get good performance with simple

  * buffer dump/reload logic, by making the in-memory buffer be a multiple

  * of the access height; then there will never be accesses across bufferload

  * boundaries.  The code will still work with overlapping access requests,

  * but it doesn't handle bufferload overlaps very efficiently.

  */

 METHODDEF(jvirt_sarray_ptr)

 request_virt_sarray (j_common_ptr cinfo, int pool_id, boolean pre_zero,

 		     JDIMENSION samplesperrow, JDIMENSION numrows,

 		     JDIMENSION maxaccess)

 /* Request a virtual 2-D sample array */

 {

   my_mem_ptr mem = (my_mem_ptr) cinfo->mem;

   jvirt_sarray_ptr result;

   /* Only IMAGE-lifetime virtual arrays are currently supported */

   if (pool_id != JPOOL_IMAGE)

     ERREXIT1(cinfo, JERR_BAD_POOL_ID, pool_id);	/* safety check */

   /* get control block */

   result = (jvirt_sarray_ptr) alloc_small(cinfo, pool_id,

 					  SIZEOF(struct jvirt_sarray_control));

   result->mem_buffer = NULL;	/* marks array not yet realized */

   result->rows_in_array = numrows;

   result->samplesperrow = samplesperrow;

   result->maxaccess = maxaccess;

   result->pre_zero = pre_zero;

   result->b_s_open = FALSE;	/* no associated backing-store object */

   result->next = mem->virt_sarray_list; /* add to list of virtual arrays */

   mem->virt_sarray_list = result;

   return result;

 }

 METHODDEF(jvirt_barray_ptr)

 request_virt_barray (j_common_ptr cinfo, int pool_id, boolean pre_zero,

 		     JDIMENSION blocksperrow, JDIMENSION numrows,

 		     JDIMENSION maxaccess)

 /* Request a virtual 2-D coefficient-block array */

 {

   my_mem_ptr mem = (my_mem_ptr) cinfo->mem;

   jvirt_barray_ptr result;

   /* Only IMAGE-lifetime virtual arrays are currently supported */

   if (pool_id != JPOOL_IMAGE)

     ERREXIT1(cinfo, JERR_BAD_POOL_ID, pool_id);	/* safety check */

   /* get control block */

   result = (jvirt_barray_ptr) alloc_small(cinfo, pool_id,

 					  SIZEOF(struct jvirt_barray_control));

   result->mem_buffer = NULL;	/* marks array not yet realized */

   result->rows_in_array = numrows;

   result->blocksperrow = blocksperrow;

   result->maxaccess = maxaccess;

   result->pre_zero = pre_zero;

   result->b_s_open = FALSE;	/* no associated backing-store object */

   result->next = mem->virt_barray_list; /* add to list of virtual arrays */

   mem->virt_barray_list = result;

   return result;

 }

 METHODDEF(void)

 realize_virt_arrays (j_common_ptr cinfo)

 /* Allocate the in-memory buffers for any unrealized virtual arrays */

 {

   my_mem_ptr mem = (my_mem_ptr) cinfo->mem;

   size_t space_per_minheight, maximum_space, avail_mem;

   size_t minheights, max_minheights;

   jvirt_sarray_ptr sptr;

   jvirt_barray_ptr bptr;

   /* Compute the minimum space needed (maxaccess rows in each buffer)

    * and the maximum space needed (full image height in each buffer).

    * These may be of use to the system-dependent jpeg_mem_available routine.

    */

   space_per_minheight = 0;

   maximum_space = 0;

   for (sptr = mem->virt_sarray_list; sptr != NULL; sptr = sptr->next) {

     if (sptr->mem_buffer == NULL) { /* if not realized yet */

       space_per_minheight += (long) sptr->maxaccess *

 			     (long) sptr->samplesperrow * SIZEOF(JSAMPLE);

       maximum_space += (long) sptr->rows_in_array *

 		       (long) sptr->samplesperrow * SIZEOF(JSAMPLE);

     }

   }

   for (bptr = mem->virt_barray_list; bptr != NULL; bptr = bptr->next) {

     if (bptr->mem_buffer == NULL) { /* if not realized yet */

       space_per_minheight += (long) bptr->maxaccess *

 			     (long) bptr->blocksperrow * SIZEOF(JBLOCK);

       maximum_space += (long) bptr->rows_in_array *

 		       (long) bptr->blocksperrow * SIZEOF(JBLOCK);

     }

   }

   if (space_per_minheight <= 0)

     return;			/* no unrealized arrays, no work */

   /* Determine amount of memory to actually use; this is system-dependent. */

   avail_mem = jpeg_mem_available(cinfo, space_per_minheight, maximum_space,

 				 mem->total_space_allocated);

   /* If the maximum space needed is available, make all the buffers full

    * height; otherwise parcel it out with the same number of minheights

    * in each buffer.

    */

   if (avail_mem >= maximum_space)

     max_minheights = 1000000000L;

   else {

     max_minheights = avail_mem / space_per_minheight;

     /* If there doesn't seem to be enough space, try to get the minimum

      * anyway.  This allows a "stub" implementation of jpeg_mem_available().

      */

     if (max_minheights <= 0)

       max_minheights = 1;

   }

   /* Allocate the in-memory buffers and initialize backing store as needed. */

   for (sptr = mem->virt_sarray_list; sptr != NULL; sptr = sptr->next) {

     if (sptr->mem_buffer == NULL) { /* if not realized yet */

       minheights = ((long) sptr->rows_in_array - 1L) / sptr->maxaccess + 1L;

       if (minheights <= max_minheights) {

 	/* This buffer fits in memory */

 	sptr->rows_in_mem = sptr->rows_in_array;

       } else {

 	/* It doesn't fit in memory, create backing store. */

 	sptr->rows_in_mem = (JDIMENSION) (max_minheights * sptr->maxaccess);

 	jpeg_open_backing_store(cinfo, & sptr->b_s_info,

 				(long) sptr->rows_in_array *

 				(long) sptr->samplesperrow *

 				(long) SIZEOF(JSAMPLE));

 	sptr->b_s_open = TRUE;

       }

       sptr->mem_buffer = alloc_sarray(cinfo, JPOOL_IMAGE,

 				      sptr->samplesperrow, sptr->rows_in_mem);

       sptr->rowsperchunk = mem->last_rowsperchunk;

       sptr->cur_start_row = 0;

       sptr->first_undef_row = 0;

       sptr->dirty = FALSE;

     }

   }

   for (bptr = mem->virt_barray_list; bptr != NULL; bptr = bptr->next) {

     if (bptr->mem_buffer == NULL) { /* if not realized yet */

       minheights = ((long) bptr->rows_in_array - 1L) / bptr->maxaccess + 1L;

       if (minheights <= max_minheights) {

 	/* This buffer fits in memory */

 	bptr->rows_in_mem = bptr->rows_in_array;

       } else {

 	/* It doesn't fit in memory, create backing store. */

 	bptr->rows_in_mem = (JDIMENSION) (max_minheights * bptr->maxaccess);

 	jpeg_open_backing_store(cinfo, & bptr->b_s_info,

 				(long) bptr->rows_in_array *

 				(long) bptr->blocksperrow *

 				(long) SIZEOF(JBLOCK));

 	bptr->b_s_open = TRUE;

       }

       bptr->mem_buffer = alloc_barray(cinfo, JPOOL_IMAGE,

 				      bptr->blocksperrow, bptr->rows_in_mem);

       bptr->rowsperchunk = mem->last_rowsperchunk;

       bptr->cur_start_row = 0;

       bptr->first_undef_row = 0;

       bptr->dirty = FALSE;

     }

   }

 }

 LOCAL(void)

 do_sarray_io (j_common_ptr cinfo, jvirt_sarray_ptr ptr, boolean writing)

 /* Do backing store read or write of a virtual sample array */

 {

   long bytesperrow, file_offset, byte_count, rows, thisrow, i;

   bytesperrow = (long) ptr->samplesperrow * SIZEOF(JSAMPLE);

   file_offset = ptr->cur_start_row * bytesperrow;

   /* Loop to read or write each allocation chunk in mem_buffer */

   for (i = 0; i < (long) ptr->rows_in_mem; i += ptr->rowsperchunk) {

     /* One chunk, but check for short chunk at end of buffer */

     rows = MIN((long) ptr->rowsperchunk, (long) ptr->rows_in_mem - i);

     /* Transfer no more than is currently defined */

     thisrow = (long) ptr->cur_start_row + i;

     rows = MIN(rows, (long) ptr->first_undef_row - thisrow);

     /* Transfer no more than fits in file */

     rows = MIN(rows, (long) ptr->rows_in_array - thisrow);

     if (rows <= 0)		/* this chunk might be past end of file! */

       break;

     byte_count = rows * bytesperrow;

     if (writing)

       (*ptr->b_s_info.write_backing_store) (cinfo, & ptr->b_s_info,

 					    (void FAR *) ptr->mem_buffer[i],

 					    file_offset, byte_count);

     else

       (*ptr->b_s_info.read_backing_store) (cinfo, & ptr->b_s_info,

 					   (void FAR *) ptr->mem_buffer[i],

 					   file_offset, byte_count);

     file_offset += byte_count;

   }

 }

 LOCAL(void)

 do_barray_io (j_common_ptr cinfo, jvirt_barray_ptr ptr, boolean writing)

 /* Do backing store read or write of a virtual coefficient-block array */

 {

   long bytesperrow, file_offset, byte_count, rows, thisrow, i;

   bytesperrow = (long) ptr->blocksperrow * SIZEOF(JBLOCK);

   file_offset = ptr->cur_start_row * bytesperrow;

   /* Loop to read or write each allocation chunk in mem_buffer */

   for (i = 0; i < (long) ptr->rows_in_mem; i += ptr->rowsperchunk) {

     /* One chunk, but check for short chunk at end of buffer */

     rows = MIN((long) ptr->rowsperchunk, (long) ptr->rows_in_mem - i);

     /* Transfer no more than is currently defined */

     thisrow = (long) ptr->cur_start_row + i;

     rows = MIN(rows, (long) ptr->first_undef_row - thisrow);

     /* Transfer no more than fits in file */

     rows = MIN(rows, (long) ptr->rows_in_array - thisrow);

     if (rows <= 0)		/* this chunk might be past end of file! */

       break;

     byte_count = rows * bytesperrow;

     if (writing)

       (*ptr->b_s_info.write_backing_store) (cinfo, & ptr->b_s_info,

 					    (void FAR *) ptr->mem_buffer[i],

 					    file_offset, byte_count);

     else

       (*ptr->b_s_info.read_backing_store) (cinfo, & ptr->b_s_info,

 					   (void FAR *) ptr->mem_buffer[i],

 					   file_offset, byte_count);

     file_offset += byte_count;

   }

 }

 METHODDEF(JSAMPARRAY)

 access_virt_sarray (j_common_ptr cinfo, jvirt_sarray_ptr ptr,

 		    JDIMENSION start_row, JDIMENSION num_rows,

 		    boolean writable)

 /* Access the part of a virtual sample array starting at start_row */

 /* and extending for num_rows rows.  writable is true if  */

 /* caller intends to modify the accessed area. */

 {

   JDIMENSION end_row = start_row + num_rows;

   JDIMENSION undef_row;

   /* debugging check */

   if (end_row > ptr->rows_in_array || num_rows > ptr->maxaccess ||

       ptr->mem_buffer == NULL)

     ERREXIT(cinfo, JERR_BAD_VIRTUAL_ACCESS);

   /* Make the desired part of the virtual array accessible */

   if (start_row < ptr->cur_start_row ||

       end_row > ptr->cur_start_row+ptr->rows_in_mem) {

     if (! ptr->b_s_open)

       ERREXIT(cinfo, JERR_VIRTUAL_BUG);

     /* Flush old buffer contents if necessary */

     if (ptr->dirty) {

       do_sarray_io(cinfo, ptr, TRUE);

       ptr->dirty = FALSE;

     }

     /* Decide what part of virtual array to access.

      * Algorithm: if target address > current window, assume forward scan,

      * load starting at target address.  If target address < current window,

      * assume backward scan, load so that target area is top of window.

      * Note that when switching from forward write to forward read, will have

      * start_row = 0, so the limiting case applies and we load from 0 anyway.

      */

     if (start_row > ptr->cur_start_row) {

       ptr->cur_start_row = start_row;

     } else {

       /* use long arithmetic here to avoid overflow & unsigned problems */

       long ltemp;

       ltemp = (long) end_row - (long) ptr->rows_in_mem;

       if (ltemp < 0)

 	ltemp = 0;		/* don't fall off front end of file */

       ptr->cur_start_row = (JDIMENSION) ltemp;

     }

     /* Read in the selected part of the array.

      * During the initial write pass, we will do no actual read

      * because the selected part is all undefined.

      */

     do_sarray_io(cinfo, ptr, FALSE);

   }

   /* Ensure the accessed part of the array is defined; prezero if needed.

    * To improve locality of access, we only prezero the part of the array

    * that the caller is about to access, not the entire in-memory array.

    */

   if (ptr->first_undef_row < end_row) {

     if (ptr->first_undef_row < start_row) {

       if (writable)		/* writer skipped over a section of array */

 	ERREXIT(cinfo, JERR_BAD_VIRTUAL_ACCESS);

       undef_row = start_row;	/* but reader is allowed to read ahead */

     } else {

       undef_row = ptr->first_undef_row;

     }

     if (writable)

       ptr->first_undef_row = end_row;

     if (ptr->pre_zero) {

       size_t bytesperrow = (size_t) ptr->samplesperrow * SIZEOF(JSAMPLE);

       undef_row -= ptr->cur_start_row; /* make indexes relative to buffer */

       end_row -= ptr->cur_start_row;

       while (undef_row < end_row) {

 	jzero_far((void FAR *) ptr->mem_buffer[undef_row], bytesperrow);

 	undef_row++;

       }

     } else {

       if (! writable)		/* reader looking at undefined data */

 	ERREXIT(cinfo, JERR_BAD_VIRTUAL_ACCESS);

     }

   }

   /* Flag the buffer dirty if caller will write in it */

   if (writable)

     ptr->dirty = TRUE;

   /* Return address of proper part of the buffer */

   return ptr->mem_buffer + (start_row - ptr->cur_start_row);

 }

 METHODDEF(JBLOCKARRAY)

 access_virt_barray (j_common_ptr cinfo, jvirt_barray_ptr ptr,

 		    JDIMENSION start_row, JDIMENSION num_rows,

 		    boolean writable)

 /* Access the part of a virtual block array starting at start_row */

 /* and extending for num_rows rows.  writable is true if  */

 /* caller intends to modify the accessed area. */

 {

   JDIMENSION end_row = start_row + num_rows;

   JDIMENSION undef_row;

   /* debugging check */

   if (end_row > ptr->rows_in_array || num_rows > ptr->maxaccess ||

       ptr->mem_buffer == NULL)

     ERREXIT(cinfo, JERR_BAD_VIRTUAL_ACCESS);

   /* Make the desired part of the virtual array accessible */

   if (start_row < ptr->cur_start_row ||

       end_row > ptr->cur_start_row+ptr->rows_in_mem) {

     if (! ptr->b_s_open)

       ERREXIT(cinfo, JERR_VIRTUAL_BUG);

     /* Flush old buffer contents if necessary */

     if (ptr->dirty) {

       do_barray_io(cinfo, ptr, TRUE);

       ptr->dirty = FALSE;

     }

     /* Decide what part of virtual array to access.

      * Algorithm: if target address > current window, assume forward scan,

      * load starting at target address.  If target address < current window,

      * assume backward scan, load so that target area is top of window.

      * Note that when switching from forward write to forward read, will have

      * start_row = 0, so the limiting case applies and we load from 0 anyway.

      */

     if (start_row > ptr->cur_start_row) {

       ptr->cur_start_row = start_row;

     } else {

       /* use long arithmetic here to avoid overflow & unsigned problems */

       long ltemp;

       ltemp = (long) end_row - (long) ptr->rows_in_mem;

       if (ltemp < 0)

 	ltemp = 0;		/* don't fall off front end of file */

       ptr->cur_start_row = (JDIMENSION) ltemp;

     }

     /* Read in the selected part of the array.

      * During the initial write pass, we will do no actual read

      * because the selected part is all undefined.

      */

     do_barray_io(cinfo, ptr, FALSE);

   }

   /* Ensure the accessed part of the array is defined; prezero if needed.

    * To improve locality of access, we only prezero the part of the array

    * that the caller is about to access, not the entire in-memory array.

    */

   if (ptr->first_undef_row < end_row) {

     if (ptr->first_undef_row < start_row) {

       if (writable)		/* writer skipped over a section of array */

 	ERREXIT(cinfo, JERR_BAD_VIRTUAL_ACCESS);

       undef_row = start_row;	/* but reader is allowed to read ahead */

     } else {

       undef_row = ptr->first_undef_row;

     }

     if (writable)

       ptr->first_undef_row = end_row;

     if (ptr->pre_zero) {

       size_t bytesperrow = (size_t) ptr->blocksperrow * SIZEOF(JBLOCK);

       undef_row -= ptr->cur_start_row; /* make indexes relative to buffer */

       end_row -= ptr->cur_start_row;

       while (undef_row < end_row) {

 	jzero_far((void FAR *) ptr->mem_buffer[undef_row], bytesperrow);

 	undef_row++;

       }

     } else {

       if (! writable)		/* reader looking at undefined data */

 	ERREXIT(cinfo, JERR_BAD_VIRTUAL_ACCESS);

     }

   }

   /* Flag the buffer dirty if caller will write in it */

   if (writable)

     ptr->dirty = TRUE;

   /* Return address of proper part of the buffer */

   return ptr->mem_buffer + (start_row - ptr->cur_start_row);

 }

 /*

  * Release all objects belonging to a specified pool.

  */

 METHODDEF(void)

 free_pool (j_common_ptr cinfo, int pool_id)

 {

   my_mem_ptr mem = (my_mem_ptr) cinfo->mem;

   small_pool_ptr shdr_ptr;

   large_pool_ptr lhdr_ptr;

   size_t space_freed;

   if (pool_id < 0 || pool_id >= JPOOL_NUMPOOLS)

     ERREXIT1(cinfo, JERR_BAD_POOL_ID, pool_id);	/* safety check */

 #ifdef MEM_STATS

   if (cinfo->err->trace_level > 1)

     print_mem_stats(cinfo, pool_id); /* print pool's memory usage statistics */

 #endif

   /* If freeing IMAGE pool, close any virtual arrays first */

   if (pool_id == JPOOL_IMAGE) {

     jvirt_sarray_ptr sptr;

     jvirt_barray_ptr bptr;

     for (sptr = mem->virt_sarray_list; sptr != NULL; sptr = sptr->next) {

       if (sptr->b_s_open) {	/* there may be no backing store */

 	sptr->b_s_open = FALSE;	/* prevent recursive close if error */

 	(*sptr->b_s_info.close_backing_store) (cinfo, & sptr->b_s_info);

       }

     }

     mem->virt_sarray_list = NULL;

     for (bptr = mem->virt_barray_list; bptr != NULL; bptr = bptr->next) {

       if (bptr->b_s_open) {	/* there may be no backing store */

 	bptr->b_s_open = FALSE;	/* prevent recursive close if error */

 	(*bptr->b_s_info.close_backing_store) (cinfo, & bptr->b_s_info);

       }

     }

     mem->virt_barray_list = NULL;

   }

   /* Release large objects */

   lhdr_ptr = mem->large_list[pool_id];

   mem->large_list[pool_id] = NULL;

   while (lhdr_ptr != NULL) {

     large_pool_ptr next_lhdr_ptr = lhdr_ptr->next;

     space_freed = lhdr_ptr->bytes_used +

 		  lhdr_ptr->bytes_left +

 		  SIZEOF(large_pool_hdr);

     jpeg_free_large(cinfo, (void FAR *) lhdr_ptr, space_freed);

     mem->total_space_allocated -= space_freed;

     lhdr_ptr = next_lhdr_ptr;

   }

   /* Release small objects */

   shdr_ptr = mem->small_list[pool_id];

   mem->small_list[pool_id] = NULL;

   while (shdr_ptr != NULL) {

     small_pool_ptr next_shdr_ptr = shdr_ptr->next;

     space_freed = shdr_ptr->bytes_used +

 		  shdr_ptr->bytes_left +

 		  SIZEOF(small_pool_hdr);

     jpeg_free_small(cinfo, (void *) shdr_ptr, space_freed);

     mem->total_space_allocated -= space_freed;

     shdr_ptr = next_shdr_ptr;

   }

 }

 /*

  * Close up shop entirely.

  * Note that this cannot be called unless cinfo->mem is non-NULL.

  */

 METHODDEF(void)

 self_destruct (j_common_ptr cinfo)

 {

   int pool;

   /* Close all backing store, release all memory.

    * Releasing pools in reverse order might help avoid fragmentation

    * with some (brain-damaged) malloc libraries.

    */

   for (pool = JPOOL_NUMPOOLS-1; pool >= JPOOL_PERMANENT; pool--) {

     free_pool(cinfo, pool);

   }

   /* Release the memory manager control block too. */

   jpeg_free_small(cinfo, (void *) cinfo->mem, SIZEOF(my_memory_mgr));

   cinfo->mem = NULL;		/* ensures I will be called only once */

   jpeg_mem_term(cinfo);		/* system-dependent cleanup */

 }

 /*

  * Memory manager initialization.

  * When this is called, only the error manager pointer is valid in cinfo!

  */

 GLOBAL(void)

 jinit_memory_mgr (j_common_ptr cinfo)

 {

   my_mem_ptr mem;

   long max_to_use;

   int pool;

   size_t test_mac;

   cinfo->mem = NULL;		/* for safety if init fails */

   /* Check for configuration errors.

    * SIZEOF(ALIGN_TYPE) should be a power of 2; otherwise, it probably

    * doesn't reflect any real hardware alignment requirement.

    * The test is a little tricky: for X>0, X and X-1 have no one-bits

    * in common if and only if X is a power of 2, ie has only one one-bit.

    * Some compilers may give an "unreachable code" warning here; ignore it.

    */

   if ((ALIGN_SIZE & (ALIGN_SIZE-1)) != 0)

     ERREXIT(cinfo, JERR_BAD_ALIGN_TYPE);

   /* MAX_ALLOC_CHUNK must be representable as type size_t, and must be

    * a multiple of ALIGN_SIZE.

    * Again, an "unreachable code" warning may be ignored here.

    * But a "constant too large" warning means you need to fix MAX_ALLOC_CHUNK.

    */

   test_mac = (size_t) MAX_ALLOC_CHUNK;

   if ((long) test_mac != MAX_ALLOC_CHUNK ||

       (MAX_ALLOC_CHUNK % ALIGN_SIZE) != 0)

     ERREXIT(cinfo, JERR_BAD_ALLOC_CHUNK);

   max_to_use = jpeg_mem_init(cinfo); /* system-dependent initialization */

   /* Attempt to allocate memory manager's control block */

   mem = (my_mem_ptr) jpeg_get_small(cinfo, SIZEOF(my_memory_mgr));

   if (mem == NULL) {

     jpeg_mem_term(cinfo);	/* system-dependent cleanup */

     ERREXIT1(cinfo, JERR_OUT_OF_MEMORY, 0);

   }

   /* OK, fill in the method pointers */

   mem->pub.alloc_small = alloc_small;

   mem->pub.alloc_large = alloc_large;

   mem->pub.alloc_sarray = alloc_sarray;

   mem->pub.alloc_barray = alloc_barray;

   mem->pub.request_virt_sarray = request_virt_sarray;

   mem->pub.request_virt_barray = request_virt_barray;

   mem->pub.realize_virt_arrays = realize_virt_arrays;

   mem->pub.access_virt_sarray = access_virt_sarray;

   mem->pub.access_virt_barray = access_virt_barray;

   mem->pub.free_pool = free_pool;

   mem->pub.self_destruct = self_destruct;

   /* Make MAX_ALLOC_CHUNK accessible to other modules */

   mem->pub.max_alloc_chunk = MAX_ALLOC_CHUNK;

   /* Initialize working state */

   mem->pub.max_memory_to_use = max_to_use;

   for (pool = JPOOL_NUMPOOLS-1; pool >= JPOOL_PERMANENT; pool--) {

     mem->small_list[pool] = NULL;

     mem->large_list[pool] = NULL;

   }

   mem->virt_sarray_list = NULL;

   mem->virt_barray_list = NULL;

   mem->total_space_allocated = SIZEOF(my_memory_mgr);

   /* Declare ourselves open for business */

   cinfo->mem = & mem->pub;

   /* Check for an environment variable JPEGMEM; if found, override the

    * default max_memory setting from jpeg_mem_init.  Note that the

    * surrounding application may again override this value.

    * If your system doesn't support getenv(), define NO_GETENV to disable

    * this feature.

    */

 #ifndef NO_GETENV

   { char * memenv;

     if ((memenv = getenv("JPEGMEM")) != NULL) {

       char ch = 'x';

       if (sscanf(memenv, "%ld%c", &max_to_use, &ch) > 0) {

 	if (ch == 'm' || ch == 'M')

 	  max_to_use *= 1000L;

 	mem->pub.max_memory_to_use = max_to_use * 1000L;

       }

     }

   }

 #endif

 }