jpg.c

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    size_t bytes_used;		/* how many bytes already used within pool */
    size_t bytes_left;		/* bytes still available in this pool */
  } hdr;
  ALIGN_TYPE dummy;		/* included in union to ensure alignment */
} 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 */
  long 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->hdr.next) {
    fprintf(stderr, "  Large chunk used %ld\n",
	    (long) lhdr_ptr->hdr.bytes_used);
  }

  for (shdr_ptr = mem->small_list[pool_id]; shdr_ptr != NULL;
       shdr_ptr = shdr_ptr->hdr.next) {
    fprintf(stderr, "  Small chunk used %ld free %ld\n",
	    (long) shdr_ptr->hdr.bytes_used,
	    (long) shdr_ptr->hdr.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.
 */

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 odd_bytes, min_request, slop;

  /* Check for unsatisfiable request (do now to ensure no overflow below) */
  if (sizeofobject > (size_t) (MAX_ALLOC_CHUNK-SIZEOF(small_pool_hdr)))
    out_of_memory(cinfo, 1);	/* request exceeds malloc's ability */

  /* Round up the requested size to a multiple of SIZEOF(ALIGN_TYPE) */
  odd_bytes = sizeofobject % SIZEOF(ALIGN_TYPE);
  if (odd_bytes > 0)
    sizeofobject += SIZEOF(ALIGN_TYPE) - odd_bytes;

  /* 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->hdr.bytes_left >= sizeofobject)
      break;			/* found pool with enough space */
    prev_hdr_ptr = hdr_ptr;
    hdr_ptr = hdr_ptr->hdr.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 = sizeofobject + SIZEOF(small_pool_hdr);
    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->hdr.next = NULL;
    hdr_ptr->hdr.bytes_used = 0;
    hdr_ptr->hdr.bytes_left = sizeofobject + slop;
    if (prev_hdr_ptr == NULL)	/* first pool in class? */
      mem->small_list[pool_id] = hdr_ptr;
    else
      prev_hdr_ptr->hdr.next = hdr_ptr;
  }

  /* OK, allocate the object from the current pool */
  data_ptr = (char *) (hdr_ptr + 1); /* point to first data byte in pool */
  data_ptr += hdr_ptr->hdr.bytes_used; /* point to place for object */
  hdr_ptr->hdr.bytes_used += sizeofobject;
  hdr_ptr->hdr.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 *)
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;
  size_t odd_bytes;

  /* Check for unsatisfiable request (do now to ensure no overflow below) */
  if (sizeofobject > (size_t) (MAX_ALLOC_CHUNK-SIZEOF(large_pool_hdr)))
    out_of_memory(cinfo, 3);	/* request exceeds malloc's ability */

  /* Round up the requested size to a multiple of SIZEOF(ALIGN_TYPE) */
  odd_bytes = sizeofobject % SIZEOF(ALIGN_TYPE);
  if (odd_bytes > 0)
    sizeofobject += SIZEOF(ALIGN_TYPE) - odd_bytes;

  /* 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));
  if (hdr_ptr == NULL)
    out_of_memory(cinfo, 4);	/* jpeg_get_large failed */
  mem->total_space_allocated += sizeofobject + SIZEOF(large_pool_hdr);

  /* Success, initialize the new pool header and add to list */
  hdr_ptr->hdr.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->hdr.bytes_used = sizeofobject;
  hdr_ptr->hdr.bytes_left = 0;
  mem->large_list[pool_id] = hdr_ptr;

  return (void *) (hdr_ptr + 1); /* point to first data byte in pool */
}


/*
 * 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.
 */

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;

  /* 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;

  /* 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,