jbig.c

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  /* prevent uint32 overflow: s->l0 * 2 ^ s->d < 2 ^ 32 */
  if (s->d > 31 || (s->d != 0 && s->l0 >= (1UL << (32 - s->d))))
    return;
  if (s->yd1 < s->yd)
    s->yd1 = s->yd;
  if (s->yd1 > s->yd)
    s->options |= JBG_VLENGTH;

  /* ensure correct zero padding of bitmap at the final byte of each line */
  if (s->xd & 7) {
    bpl = jbg_ceil_half(s->xd, 3);     /* bytes per line */
    for (plane = 0; plane < s->planes; plane++)
      for (y = 0; y < s->yd; y++)
	s->lhp[0][plane][y * bpl + bpl - 1] &= ~((1 << (8 - (s->xd & 7))) - 1);
  }

  /* prepare BIH */
  buf[0] = s->dl;
  buf[1] = s->dh;
  buf[2] = s->planes;
  buf[3] = 0;
  xd = jbg_ceil_half(s->xd, s->d - s->dh);
  yd = jbg_ceil_half(s->yd1, s->d - s->dh);
  buf[4] = (unsigned char)(xd >> 24);
  buf[5] = (unsigned char)((xd >> 16) & 0xff);
  buf[6] = (unsigned char)((xd >> 8) & 0xff);
  buf[7] = (unsigned char)(xd & 0xff);
  buf[8] = (unsigned char)(yd >> 24);
  buf[9] = (unsigned char)((yd >> 16) & 0xff);
  buf[10] = (unsigned char)((yd >> 8) & 0xff);
  buf[11] = (unsigned char)(yd & 0xff);
  buf[12] = (unsigned char)(s->l0 >> 24);
  buf[13] = (unsigned char)((s->l0 >> 16) & 0xff);
  buf[14] = (unsigned char)((s->l0 >> 8) & 0xff);
  buf[15] = (unsigned char)(s->l0 & 0xff);
  buf[16] = (unsigned char)(s->mx);
  buf[17] = (unsigned char)(s->my);
  buf[18] = (unsigned char)(s->order);
  buf[19] = (unsigned char)(s->options & 0x7f);

#if 0
  /* sanitize L0 (if it was set to 0xffffffff for T.85-style NEWLEN tests) */
  if (s->l0 > (s->yd >> s->d))
    s->l0 = s->yd >> s->d;
#endif

  /* calculate number of stripes that will be required */
  s->stripes = jbg_stripes(s->l0, s->yd, s->d);

  /* allocate buffers for SDE pointers */
  if (s->sde == NULL) {
    s->sde = (struct jbg_buf ****)
      checked_malloc(s->stripes, sizeof(struct jbg_buf ***));
    for (stripe = 0; stripe < s->stripes; stripe++) {
      s->sde[stripe] = (struct jbg_buf ***)
	checked_malloc(s->d + 1, sizeof(struct jbg_buf **));
      for (layer = 0; layer < s->d + 1; layer++) {
	s->sde[stripe][layer] = (struct jbg_buf **)
	  checked_malloc(s->planes, sizeof(struct jbg_buf *));
	for (plane = 0; plane < s->planes; plane++)
	  s->sde[stripe][layer][plane] = SDE_TODO;
      }
    }
  }

  /* output BIH */
  s->data_out(buf, 20, s->file);
  if ((s->options & (JBG_DPON | JBG_DPPRIV | JBG_DPLAST)) ==
      (JBG_DPON | JBG_DPPRIV)) {
    /* write private table */
    jbg_int2dppriv(dpbuf, s->dppriv);
    s->data_out(dpbuf, 1728, s->file);
  }

#if 0
  /*
   * Encode everything first. This is a simple-minded alternative to
   * all the tricky on-demand encoding logic in output_sde() for
   * debugging purposes.
   */
  for (layer = s->dh; layer >= s->dl; layer--) {
    for (plane = 0; plane < s->planes; plane++) {
      if (layer > 0)
	resolution_reduction(s, plane, layer);
      for (stripe = 0; stripe < s->stripes; stripe++)
	encode_sde(s, stripe, layer, plane);
      s->highres[plane] ^= 1;
    }
  }
#endif

  /*
   * Generic loops over all SDEs. Which loop represents layer, plane and
   * stripe depends on the option flags.
   */

  /* start and end value vor each loop */
  is[iindex[order][STRIPE]] = 0;
  ie[iindex[order][STRIPE]] = s->stripes - 1;
  is[iindex[order][LAYER]] = s->dl;
  ie[iindex[order][LAYER]] = s->dh;
  is[iindex[order][PLANE]] = 0;
  ie[iindex[order][PLANE]] = s->planes - 1;

  for (ii[0] = is[0]; ii[0] <= ie[0]; ii[0]++)
    for (ii[1] = is[1]; ii[1] <= ie[1]; ii[1]++)
      for (ii[2] = is[2]; ii[2] <= ie[2]; ii[2]++) {
	
	stripe = ii[iindex[order][STRIPE]];
	if (s->order & JBG_HITOLO)
	  layer = s->dh - (ii[iindex[order][LAYER]] - s->dl);
	else
	  layer = ii[iindex[order][LAYER]];
	plane = ii[iindex[order][PLANE]];

	output_sde(s, stripe, layer, plane);

	/*
	 * When we generate a NEWLEN test case (s->yd1 > s->yd), output
	 * NEWLEN after last stripe if we have only a single
	 * resolution layer or plane (see ITU-T T.85 profile), otherwise
	 * output NEWLEN before last stripe.
	 */
	if (s->yd1 > s->yd &&
	    (stripe == s->stripes - 1 ||
	     (stripe == s->stripes - 2 && 
	      (s->dl != s->dh || s->planes > 1)))) {
	  s->yd1 = s->yd;
	  yd = jbg_ceil_half(s->yd, s->d - s->dh);
	  buf[0] = MARKER_ESC;
	  buf[1] = MARKER_NEWLEN;
	  buf[2] = (unsigned char)(yd >> 24);
	  buf[3] = (unsigned char)((yd >> 16) & 0xff);
	  buf[4] = (unsigned char)((yd >> 8) & 0xff);
	  buf[5] = (unsigned char)(yd & 0xff);
	  s->data_out(buf, 6, s->file);
#ifdef DEBUG
	  fprintf(stderr, "NEWLEN: yd=%lu\n", yd);
#endif
	  if (stripe == s->stripes - 1) {
	    buf[1] = MARKER_SDNORM;
	    s->data_out(buf, 2, s->file);
	  }
	}

      }

  return;
}


void jbg_enc_free(struct jbg_enc_state *s)
{
  unsigned long stripe;
  int layer, plane;

#ifdef DEBUG
  fprintf(stderr, "jbg_enc_free(%p)\n", (void *) s);
#endif

  /* clear buffers for SDEs */
  if (s->sde) {
    for (stripe = 0; stripe < s->stripes; stripe++) {
      for (layer = 0; layer < s->d + 1; layer++) {
	for (plane = 0; plane < s->planes; plane++)
	  if (s->sde[stripe][layer][plane] != SDE_DONE &&
	      s->sde[stripe][layer][plane] != SDE_TODO)
	    jbg_buf_free(&s->sde[stripe][layer][plane]);
	checked_free(s->sde[stripe][layer]);
      }
      checked_free(s->sde[stripe]);
    }
    checked_free(s->sde);
  }

  /* clear free_list */
  jbg_buf_free(&s->free_list);

  /* clear memory for arithmetic encoder states */
  checked_free(s->s);

  /* clear memory for differential-layer typical prediction buffer */
  checked_free(s->tp);

  /* clear memory for adaptive template pixel offsets */
  checked_free(s->tx);

  /* clear lowres image buffers */
  if (s->lhp[1]) {
    for (plane = 0; plane < s->planes; plane++)
      checked_free(s->lhp[1][plane]);
    checked_free(s->lhp[1]);
  }
  
  /* clear buffer for index of highres image in lhp */
  checked_free(s->highres);
  
  return;
}


/*
 * Convert the error codes used by jbg_dec_in() into a string
 * written in the selected language and character set.
 */
const char *jbg_strerror(int errnum, int language)
{
  if (errnum < 0 || errnum >= NEMSG)
    return "Unknown error code passed to jbg_strerror()";
  if (language < 0 || language >= NEMSG_LANG)
    return "Unknown language code passed to jbg_strerror()";

  return errmsg[language][errnum];
}


/*
 * The constructor for a decoder 
 */
void jbg_dec_init(struct jbg_dec_state *s)
{
  s->order = 0;
  s->d = -1;
  s->bie_len = 0;
  s->buf_len = 0;
  s->dppriv = NULL;
  s->xmax = 4294967295UL;
  s->ymax = 4294967295UL;
  s->dmax = 256;
  s->s = NULL;

  return;
}


/*
 * Specify a maximum image size for the decoder. If the JBIG file has
 * the order bit ILEAVE, but not the bit SEQ set, then the decoder
 * will abort to decode after the image has reached the maximal
 * resolution layer which is still not wider than xmax or higher than
 * ymax.
 */
void jbg_dec_maxsize(struct jbg_dec_state *s, unsigned long xmax,
		     unsigned long ymax)
{
  if (xmax > 0) s->xmax = xmax;
  if (ymax > 0) s->ymax = ymax;

  return;
}


/*
 * Decode the new len PSDC bytes to which data points and add them to
 * the current stripe. Return the number of bytes which have actually
 * been read (this will be less than len if a marker segment was 
 * part of the data or if the final byte was 0xff were this code
 * can not determine, whether we have a marker segment.
 */
static size_t decode_pscd(struct jbg_dec_state *s, unsigned char *data,
			  size_t len)
{
  unsigned long stripe;
  unsigned int layer, plane;
  unsigned long hl, ll, y, hx, hy, lx, ly, hbpl, lbpl;
  unsigned char *hp, *lp1, *lp2, *p1, *q1;
  register unsigned long line_h1, line_h2, line_h3;
  register unsigned long line_l1, line_l2, line_l3;
  struct jbg_ardec_state *se;
  unsigned long x;
  long o;
  unsigned a;
  int n;
  int pix, cx = 0, slntp, tx;

  /* SDE loop variables */
  stripe = s->ii[iindex[s->order & 7][STRIPE]];
  layer = s->ii[iindex[s->order & 7][LAYER]];
  plane = s->ii[iindex[s->order & 7][PLANE]];

  /* forward data to arithmetic decoder */
  se = s->s[plane] + layer - s->dl;
  se->pscd_ptr = data;
  se->pscd_end = data + len;
  
  /* 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 + s->i;
  /* 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 = jbg_ceil_half(hx, 3);
  lbpl = jbg_ceil_half(lx, 3);
  /* pointer to highres and lowres image bytes */
  hp  = s->lhp[ layer    & 1][plane] + (stripe * hl + s->i) * hbpl +
    (s->x >> 3);
  lp2 = s->lhp[(layer-1) & 1][plane] + (stripe * ll + (s->i >> 1)) * lbpl +
    (s->x >> 4);
  lp1 = lp2 + lbpl;

  /* restore a few local variables */
  line_h1 = s->line_h1;
  line_h2 = s->line_h2;
  line_h3 = s->line_h3;
  line_l1 = s->line_l1;
  line_l2 = s->line_l2;
  line_l3 = s->line_l3;
  x = s->x;

  if (s->x == 0 && s->i == 0 &&
      (stripe == 0 || s->reset[plane][layer - s->dl])) {
    s->tx[plane][layer - s->dl] = s->ty[plane][layer - s->dl] = 0;
    if (s->pseudo)
      s->lntp[plane][layer - s->dl] = 1;
  }

#ifdef DEBUG
  if (s->x == 0 && s->i == 0 && s->pseudo)
    fprintf(stderr, "decode_pscd(%p, %p, %ld): s/d/p = %2lu/%2u/%2u\n",
	    (void *) s, (void *) data, (long) len, stripe, layer, plane);
#endif

  if (layer == 0) {

    /*
     *  Decode lowest resolution layer
     */

    for (; s->i < hl && y < hy; s->i++, y++) {

      /* adaptive template changes */
      if (x == 0)
	for (n = 0; n < s->at_moves; n++)
	  if (s->at_line[n] == s->i) {
	    s->tx[plane][layer - s->dl] = s->at_tx[n];
	    s->ty[plane][layer - s->dl] = s->at_ty[n];
#ifdef DEBUG
	    fprintf(stderr, "ATMOVE: line=%lu, tx=%d, ty=%d.\n", s->i,
		    s->tx[plane][layer - s->dl], s->ty[plane][layer - s->dl]);
#endif
	  }
      tx = s->tx[plane][layer - s->dl];
      assert(tx >= 0); /* i.e., tx can safely be cast to unsigned */

      /* typical prediction */
      if (s->options & JBG_TPBON && s->pseudo) {
	slntp = arith_decode(se, (s->options & JBG_LRLTWO) ? TPB2CX : TPB3CX);
	if (se->result == JBG_MORE || se->result == JBG_MARKER)
	  goto leave;
	s->lntp[plane][layer - s->dl] =
	  !(slntp ^ s->lntp[plane][layer - s->dl]);
	if (s->lntp[plane][layer - s->dl]) {
	  /* this line is 'not typical' and has to be coded completely */
	  s->pseudo = 0;
	} else {
	  /* this line is 'typical' (i.e. identical to the previous one) */
	  p1 = hp;
	  if (s->i == 0 && (stripe == 0 || s->reset[plane][layer - s->dl]))
	    while (p1 < hp + hbpl) *p1++ = 0;
	  else {
	    q1 = hp - hbpl;
	    while (q1 < hp) *p1++ = *q1++;
	  }
	  hp += hbpl;
	  continue;
	}
      }
      
      /*
       * Layout of the variables line_h1, line_h2, line_h3, which contain
       * as bits the neighbour pixels of the currently decoded pixel X:
       *
       *                     76543210 76543210 76543210 76543210     line_h3
       *                     76543210 76543210 76543210 76543210     line_h2
       *   76543210 76543210 76543210 76543210 X                     line_h1
       */
      
      if (x == 0) {
	line_h1 = line_h2 = line_h3 = 0;
	if (s->i > 0 || (y > 0 && !s->reset[plane][layer - s->dl]))
	  line_h2 = (long)*(hp - hbpl) << 8;
	if (s->i > 1 || (y > 1 && !s->reset[plane][layer - s->dl]))
	  line_h3 = (long)*(hp - hbpl - hbpl) << 8;
      }
      
      /*
       * Another tiny JBIG standard bug:
       *
       * While implementing the line_h3 handling here, I discovered
       * another problem with the ITU-T T.82(1993 E) specification.
       * This might be a somewhat pathological case, however. The
       * standard is unclear about how a decoder should behave in the
       * following situation:
       *
       * Assume we are in layer 0 and all stripes are single lines
       * (L0=1 allowed by table 9). We are now decoding the first (and
       * only) line of the third stripe. Assume, the first stripe was
       * terminated by SDRST and the second stripe was terminated by
       * SDNORM. While decoding the only line of the third stripe with
       * the three-line template, we need access to pixels from the
       * previous two stripes. We know that the previous stripe
       * terminated with SDNROM, so we access the pixel from the
       * second stripe. But do we have to replace the pixels from the
       * first stripe by background pixels, because this stripe ended
       * with SDRST? The standard, especially clause 6.2.5 does never
       * mention this case, so the behaviour is undefined here. My
       * current implementation remembers only the marker used to
       * terminate the previous stripe. In the above example, the
       * pixels of the first stripe are accessed despite the fact that
       * this stripe ended with SDRST. An alternative (only slightly
       * more complicated) implementation would be to remember the end
       * marker (SDNORM or SDRST) of the previous two stripes in a
       * plane/layer and to act accordingly when accessing the two
       * previous lines. What am I supposed to do here?
       *
       * As the standard is unclear about the correct behaviour in the
       * situation of the above example, I strongly suggest to avoid
       * the following situation while encoding data with JBIG:
       *
       *   LRLTWO = 0, L0=1 and both SDNORM and SDRST appear in layer 0.
       *
       * I guess that only a very few if any encoders will switch
       * between SDNORM and SDRST, so let us hope that this ambiguity
       * in the standard will never cause any interoperability
       * problems.
       *
       * Markus Kuhn -- 1995-04-30
       */

      /* decode line */
      while (x < hx) {
	if ((x & 7) == 0) {
	  if (x < hbpl * 8 - 8 &&
	      (s->i > 0 || (y > 0 && !s->reset[plane][layer - s->dl]))) {
	    line_h2 |= *(hp - hbpl + 1);