jbig.c

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	s->ct += 8;
	s->result = JBG_OK;
      }
    }
    s->c <<= 1;
    s->a <<= 1;
    --s->ct;
    if (s->a == 0x10000L)
      s->startup = 0;
  }

  st = s->st + cx;
  ss = *st & 0x7f;
  assert(ss < 113);
  lsz = jbg_lsz[ss];

#if 0
  fprintf(stderr, "cx = %d, mps = %d, st = %3d, lsz = 0x%04x, a = 0x%05lx, "
	  "c = 0x%08lx, ct = %2d\n",
	  cx, !!(s->st[cx] & 0x80), ss, lsz, s->a, s->c, s->ct);
#endif

  if ((s->c >> 16) < (s->a -= lsz))
    if (s->a & 0xffff8000L)
      return *st >> 7;
    else {
      /* MPS_EXCHANGE */
      if (s->a < lsz) {
	pix = 1 - (*st >> 7);
	/* Check whether MPS/LPS exchange is necessary
	 * and chose next probability estimator status */
	*st &= 0x80;
	*st ^= jbg_nlps[ss];
      } else {
	pix = *st >> 7;
	*st &= 0x80;
	*st |= jbg_nmps[ss];
      }
    }
  else {
    /* LPS_EXCHANGE */
    if (s->a < lsz) {
      s->c -= s->a << 16;
      s->a = lsz;
      pix = *st >> 7;
      *st &= 0x80;
      *st |= jbg_nmps[ss];
    } else {
      s->c -= s->a << 16;
      s->a = lsz;
      pix = 1 - (*st >> 7);
      /* Check whether MPS/LPS exchange is necessary
       * and chose next probability estimator status */
      *st &= 0x80;
      *st ^= jbg_nlps[ss];
    }
  }

  return pix;
}



/*
 * Memory management for buffers which are used for temporarily
 * storing SDEs by the encoder.
 *
 * The following functions manage a set of struct jbg_buf storage
 * containers were each can keep JBG_BUFSIZE bytes. The jbg_buf
 * containers can be linked to form linear double-chained lists for
 * which a number of operations are provided. Blocks which are
 * tempoarily not used any more are returned to a freelist which each
 * encoder keeps. Only the destructor of the encoder actually returns
 * the block via checked_free() to the stdlib memory management.
 */


/*
 * Allocate a new buffer block and initialize it. Try to get it from
 * the free_list, and if it is empty, call checked_malloc().
 */
static struct jbg_buf *jbg_buf_init(struct jbg_buf **free_list)
{
  struct jbg_buf *new_block;
  
  /* Test whether a block from the free list is available */
  if (*free_list) {
    new_block = *free_list;
    *free_list = new_block->next;
  } else {
    /* request a new memory block */
    new_block = (struct jbg_buf *) checked_malloc(sizeof(struct jbg_buf));
  }
  new_block->len = 0;
  new_block->next = NULL;
  new_block->previous = NULL;
  new_block->last = new_block;
  new_block->free_list = free_list;

  return new_block;
}


/*
 * Return an entire free_list to the memory management of stdlib.
 * This is only done by jbg_enc_free().
 */
static void jbg_buf_free(struct jbg_buf **free_list)
{
  struct jbg_buf *tmp;
  
  while (*free_list) {
    tmp = (*free_list)->next;
    checked_free(*free_list);
    *free_list = tmp;
  }
  
  return;
}


/*
 * Append a single byte to a single list that starts with the block
 * *(struct jbg_buf *) head. The type of *head is void here in order to
 * keep the interface of the arithmetic encoder gereric, which uses this
 * function as a call-back function in order to deliver single bytes
 * for a PSCD.
 */
static void jbg_buf_write(int b, void *head)
{
  struct jbg_buf *now;

  now = ((struct jbg_buf *) head)->last;
  if (now->len < JBG_BUFSIZE - 1) {
    now->d[now->len++] = b;
    return;
  }
  now->next = jbg_buf_init(((struct jbg_buf *) head)->free_list);
  now->next->previous = now;
  now->next->d[now->next->len++] = b;
  ((struct jbg_buf *) head)->last = now->next;

  return;
}


/*
 * Remove any trailing zero bytes from the end of a linked jbg_buf list,
 * however make sure that no zero byte is removed which directly
 * follows a 0xff byte (i.e., keep MARKER_ESC MARKER_STUFF sequences
 * intact). This function is used to remove any redundant final zero
 * bytes from a PSCD.
 */
static void jbg_buf_remove_zeros(struct jbg_buf *head)
{
  struct jbg_buf *last;

  while (1) {
    /* remove trailing 0x00 in last block of list until this block is empty */
    last = head->last;
    while (last->len && last->d[last->len - 1] == 0)
      last->len--;
    /* if block became really empty, remove it in case it is not the
     * only remaining block and then loop to next block */
    if (last->previous && !last->len) {
      head->last->next = *head->free_list;
      *head->free_list = head->last;
      head->last = last->previous;
      head->last->next = NULL;
    } else
      break;
  }

  /*
   * If the final non-zero byte is 0xff (MARKER_ESC), then we just have
   * removed a MARKER_STUFF and we will append it again now in order
   * to preserve PSCD status of byte stream.
   */
  if (head->last->len && head->last->d[head->last->len - 1] == MARKER_ESC)
    jbg_buf_write(MARKER_STUFF, head);
 
  return;
}


/*
 * The jbg_buf list which starts with block *new_prefix is concatenated
 * with the list which starts with block **start and *start will then point
 * to the first block of the new list.
 */
static void jbg_buf_prefix(struct jbg_buf *new_prefix, struct jbg_buf **start)
{
  new_prefix->last->next = *start;
  new_prefix->last->next->previous = new_prefix->last;
  new_prefix->last = new_prefix->last->next->last;
  *start = new_prefix;
  
  return;
}


/*
 * Send the contents of a jbg_buf list that starts with block **head to
 * the call back function data_out and return the blocks of the jbg_buf
 * list to the freelist from which these jbg_buf blocks have been taken.
 * After the call, *head == NULL.
 */
static void jbg_buf_output(struct jbg_buf **head,
			void (*data_out)(unsigned char *start,
					 size_t len, void *file),
			void *file)
{
  struct jbg_buf *tmp;
  
  while (*head) {
    data_out((*head)->d, (*head)->len, file);
    tmp = (*head)->next;
    (*head)->next = *(*head)->free_list;
    *(*head)->free_list = *head;
    *head = tmp;
  }
  
  return;
}


/*
 * Calculate y = ceil(x/2) applied n times. This function is used to
 * determine the number of pixels per row or column after n resolution
 * reductions. E.g. X[d-1] = jbg_ceil_half(X[d], 1) and X[0] =
 * jbg_ceil_half(X[d], d) as defined in clause 6.2.3 of T.82.
 */
unsigned long jbg_ceil_half(unsigned long x, int n)
{
  unsigned long mask;
  
  mask = (1UL << n) - 1;     /* the lowest n bits are 1 here */
  return (x >> n) + ((mask & x) != 0);
}


/*
 * Initialize the status struct for the encoder.
 */
void jbg_enc_init(struct jbg_enc_state *s, unsigned long x, unsigned long y,
                  int planes, unsigned char **p,
                  void (*data_out)(unsigned char *start, size_t len,
				   void *file),
		  void *file)
{
  unsigned long l, lx;
  int i;
  size_t bufsize;

  extern char jbg_resred[], jbg_dptable[];

  s->xd = x;
  s->yd = y;
  s->planes = planes;
  s->data_out = data_out;
  s->file = file;

  s->d = 0;
  s->dl = 0;
  s->dh = s->d;
  s->l0 = jbg_ceil_half(s->yd, s->d) / 35;   /* 35 stripes/image */
  while ((s->l0 << s->d) > 128)              /* but <= 128 lines/stripe */
    --s->l0;
  if (s->l0 < 2) s->l0 = 2;
  s->mx = 8;
  s->my = 0;
  s->order = JBG_ILEAVE | JBG_SMID;
  s->options = JBG_TPBON | JBG_TPDON | JBG_DPON;
  s->dppriv = jbg_dptable;
  s->res_tab = jbg_resred;
  
  s->highres = checked_malloc(planes * sizeof(int));
  s->lhp[0] = p;
  s->lhp[1] = checked_malloc(planes * sizeof(unsigned char *));
  bufsize = ((jbg_ceil_half(x, 1) + 7) / 8) * jbg_ceil_half(y, 1);
  for (i = 0; i < planes; i++) {
    s->highres[i] = 0;
    s->lhp[1][i] = checked_malloc(sizeof(unsigned char) * bufsize);
  }
  
  s->free_list = NULL;
  s->s = (struct jbg_arenc_state *) 
    checked_malloc(s->planes * sizeof(struct jbg_arenc_state));
  s->tx = (int *) checked_malloc(s->planes * sizeof(int));
  lx = jbg_ceil_half(x, 1);
  s->tp = (char *) checked_malloc(lx * sizeof(char));
  for (l = 0; l < lx; s->tp[l++] = 2);
  s->sde = NULL;

  return;
}


/*
 * This function selects the number of differential layers based on
 * the maximum size requested for the lowest resolution layer. If
 * possible, a number of differential layers is selected, which will
 * keep the size of the lowest resolution layer below or equal to the
 * given width x and height y. However not more than 6 differential
 * resolution layers will be used. In addition, a reasonable value for
 * l0 (height of one stripe in the lowest resolution layer) is
 * selected, which obeys the recommended limitations for l0 in annex A
 * and C of the JBIG standard. The selected number of resolution layers
 * is returned. 
 */
int jbg_enc_lrlmax(struct jbg_enc_state *s, unsigned long x, 
		   unsigned long y)
{
  for (s->d = 0; s->d < 6; s->d++)
    if (jbg_ceil_half(s->xd, s->d) <= x && jbg_ceil_half(s->yd, s->d) <= y)
      break;
  s->dl = 0;
  s->dh = s->d;

  s->l0 = jbg_ceil_half(s->yd, s->d) / 35;  /* 35 stripes/image */
  while ((s->l0 << s->d) > 128)             /* but <= 128 lines/stripe */
    --s->l0;
  if (s->l0 < 2) s->l0 = 2;

  return s->d;
}


/*
 * As an alternative to jbg_enc_lrlmax(), the following function allows
 * to specify the number of layers directly. The stripe height and layer
 * range is also adjusted automatically here.
 */
void jbg_enc_layers(struct jbg_enc_state *s, int d)
{
  if (d < 0 || d > 255)
    return;
  s->d  = d;
  s->dl = 0;
  s->dh = s->d;

  s->l0 = jbg_ceil_half(s->yd, s->d) / 35;  /* 35 stripes/image */
  while ((s->l0 << s->d) > 128)             /* but <= 128 lines/stripe */
    --s->l0;
  if (s->l0 < 2) s->l0 = 2;

  return;
}


/*
 * Specify the highest and lowest resolution layers which will be
 * written to the output file. Call this function not before
 * jbg_enc_layers() or jbg_enc_lrlmax(), because these two functions
 * reset the lowest and highest resolution layer to default values.
 * Negative values are ignored. The total number of layers is returned.
 */
int jbg_enc_lrange(struct jbg_enc_state *s, int dl, int dh)
{
  if (dl >= 0     && dl <= s->d) s->dl = dl;
  if (dh >= s->dl && dh <= s->d) s->dh = dh;

  return s->d;
}


/*
 * The following function allows to specify the bits describing the
 * options of the format as well as the maximum AT movement window and
 * the number of layer 0 lines per stripes.
 */
void jbg_enc_options(struct jbg_enc_state *s, int order, int options,
		     long l0, int mx, int my)
{
  if (order >= 0 && order <= 0x0f) s->order = order;
  if (options >= 0) s->options = options;
  if (l0 >= 0) s->l0 = l0;
  if (mx >= 0 && my < 128) s->mx = mx;
  if (my >= 0 && my < 256) s->my = my;

  return;
}


/*
 * This function actually does all the tricky work involved in producing
 * a SDE, which is stored in the appropriate s->sde[][][] element
 * for later output in the correct order.
 */
static void encode_sde(struct jbg_enc_state *s,
		       long stripe, int layer, int plane)
{
  unsigned char *hp, *lp1, *lp2, *p0, *p1, *q1, *q2;
  unsigned long hl, ll, hx, hy, lx, ly, hbpl, lbpl;
  unsigned long line_h0 = 0, line_h1 = 0;
  unsigned long line_h2, line_h3, line_l1, line_l2, line_l3;
  struct jbg_arenc_state *se;
  unsigned long i, j, y;
  unsigned t;
  int ltp, ltp_old, cx;
  unsigned long c_all, c[MX_MAX + 1], cmin, cmax, clmin, clmax;
  int tmax, at_determined;
  int new_tx;
  long new_tx_line = -1;
  struct jbg_buf *new_jbg_buf;

#ifdef DEBUG
  static long tp_lines, tp_exceptions, tp_pixels, dp_pixels;
  static long encoded_pixels;
#endif

  /* return immediately if this stripe has already been encoded */
  if (s->sde[stripe][layer][plane] != SDE_TODO)
    return;

#ifdef DEBUG
  if (stripe == 0)
    tp_lines = tp_exceptions = tp_pixels = dp_pixels = encoded_pixels = 0;
  fprintf(stderr, "encode_sde: s/d/p = %2ld/%2d/%2d\n",
	  stripe, layer, plane);
#endif

  /* number of lines per stripe in highres image */
  hl = s->l0 << layer;
  /* number of lines per stripe in lowres image */
  ll = hl >> 1;
  /* current line number in highres image */
  y = stripe * hl;
  /* number of pixels in highres image */
  hx = jbg_ceil_half(s->xd, s->d - layer);
  hy = jbg_ceil_half(s->yd, s->d - layer);
  /* number of pixels in lowres image */
  lx = jbg_ceil_half(hx, 1);
  ly = jbg_ceil_half(hy, 1);
  /* bytes per line in highres and lowres image */
  hbpl = (hx + 7) / 8;
  lbpl = (lx + 7) / 8;
  /* pointer to first image byte of highres stripe */
  hp = s->lhp[s->highres[plane]][plane] + stripe * hl * hbpl;
  lp2 = s->lhp[1 - s->highres[plane]][plane] + stripe * ll * lbpl;
  lp1 = lp2 + lbpl;
  
  /* initialize arithmetic encoder */