configured_jbig.c

基于ADI BLACKFIN的jbig压缩和解压缩程序

  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


    /*
     *  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 = s->at_tx[n];
	    s->ty = 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;
      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 =
	  !(slntp ^ s->lntp);
	if (s->lntp) {
	  /* 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))
	    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))
	  line_h2 = (long)*(hp - hbpl) << 8;
	if (s->i > 1 || (y > 1 && !s->reset))
	  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))) {
	    line_h2 |= *(hp - hbpl + 1);
	    if (s->i > 1 || (y > 1 && !s->reset))
	      line_h3 |= *(hp - hbpl - hbpl + 1);
	  }
	}
	  /* three line template */
	  do {
	    if (tx) {
	      if ((unsigned) tx > x)
		a = 0;
	      else if (tx < 8)
		a = ((line_h1 >> (tx - 3)) & 0x004);
	      else {
		o = (x - tx) - (x & ~7L);
		a = (hp[o >> 3] >> (7 - (o & 7))) & 1;
		a <<= 2;
	      }
	      assert(tx > 31 ||
		     a == ((line_h1 >> (tx - 3)) & 0x004));
	      pix = arith_decode(se, (((line_h3 >>  7) & 0x380) |
				      ((line_h2 >> 11) & 0x078) | a |
				      (line_h1 & 0x003)));
	    } else
	      pix = arith_decode(se, (((line_h3 >>  7) & 0x380) |
				      ((line_h2 >> 11) & 0x07c) |
				      (line_h1 & 0x003)));
	    if (se->result == JBG_MORE || se->result == JBG_MARKER)
	      goto leave;
	    
	    line_h1 = (line_h1 << 1) | pix;
	    line_h2 <<= 1;
	    line_h3 <<= 1;
	  } while ((++x & 7) && x < hx);
	 /* if (s->options & JBG_LRLTWO) */
	*hp++ = (unsigned char)line_h1;
      } /* while */
      *(hp - 1) <<= hbpl * 8 - hx;
      x = 0;
      s->pseudo = 1;
    } /* for (i = ...) */

 leave:

  /* save a few local variables */
  s->line_h1 = line_h1;
  s->line_h2 = line_h2;
  s->line_h3 = line_h3;

  s->x = x;

  return se->pscd_ptr - data;
}


/*
 * Provide a new BIE fragment to the decoder.
 *
 * If cnt is not NULL, then *cnt will contain after the call the
 * number of actually read bytes. If the data was not complete, then
 * the return value will be JBG_EAGAIN and *cnt == len. In case this
 * function has returned with JBG_EOK, then it has reached the end of
 * a BIE but it can be called again with data from the next BIE if
 * there exists one in order to get to a higher resolution layer. In
 * case the return value was JBG_EOK_INTR then this function can be
 * called again with the rest of the BIE, because parsing the BIE has
 * been interrupted by a jbg_dec_maxsize() specification. In both
 * cases the remaining len - *cnt bytes of the previous block will
 * have to passed to this function again (if len > *cnt). In case of
 * any other return value than JBG_EOK, JBG_EOK_INTR or JBG_EAGAIN, a
 * serious problem has occured and the only function you should call
 * is jbg_dec_free() in order to remove the mess (and probably
 * jbg_strerror() in order to find out what to tell the user).
 */
int jbg_dec_in(struct jbg_dec_state *s, unsigned char *data, size_t len,
	       size_t *cnt)
{
  int  j, required_length;
  unsigned long x, y;

  size_t dummy_cnt;

  if (!cnt) cnt = &dummy_cnt;
  *cnt = 0;
  if (len < 1) return JBG_EAGAIN;

  /* read in 20-byte BIH */
  if (s->bie_len < 20) {
    while (s->bie_len < 20 && *cnt < len)
      s->buffer[s->bie_len++] = data[(*cnt)++];
    if (s->bie_len < 20) 
      return JBG_EAGAIN;
    if (s->buffer[1] < s->buffer[0])
      return JBG_EINVAL;
    /* test whether this looks like a valid JBIG header at all */
    if (s->buffer[3] != 0 || (s->buffer[18] & 0xf0) != 0 ||
	(s->buffer[19] & 0x80) != 0)
      return JBG_EINVAL;
    if (s->buffer[0] != s->d + 1)
      return JBG_ENOCONT;
    s->dl = s->buffer[0];
    s->d = s->buffer[1];
    if (s->dl == 0)
      s->planes = s->buffer[2];
    else
      if (s->planes != s->buffer[2])
	return JBG_ENOCONT;
    x = (((long) s->buffer[ 4] << 24) | ((long) s->buffer[ 5] << 16) |
	 ((long) s->buffer[ 6] <<  8) | (long) s->buffer[ 7]);
    y = (((long) s->buffer[ 8] << 24) | ((long) s->buffer[ 9] << 16) |
	 ((long) s->buffer[10] <<  8) | (long) s->buffer[11]);
    if (s->dl != 0 && ((s->xd << (s->d - s->dl + 1)) != x &&
		       (s->yd << (s->d - s->dl + 1)) != y))
      return JBG_ENOCONT;
    s->xd = x;
    s->yd = y;
    s->l0 = (((long) s->buffer[12] << 24) | ((long) s->buffer[13] << 16) |
	     ((long) s->buffer[14] <<  8) | (long) s->buffer[15]);
    /* ITU-T T.85 trick not directly supported by decoder; for full
     * T.85 compatibility with respect to all NEWLEN marker scenarios,
     * preprocess BIE with jbg_newlen() before passing it to the decoder. */
    if (s->yd == 0xffffffff)
      return JBG_EIMPL;
    if (!s->planes || !s->xd || !s->yd || !s->l0)
      return JBG_EINVAL;
    /* prevent uint32 overflow: s->l0 * 2 ^ s->d < 2 ^ 32 */
    if (s->d > 31 || (s->d != 0 && s->l0 >= (1UL << (32 - s->d))))
      return JBG_EIMPL;
    s->mx = s->buffer[16];
    if (s->mx > 127)
      return JBG_EINVAL;
    s->my = s->buffer[17];

    s->order = s->buffer[18];
  
    s->options = s->buffer[19];

    /* calculate number of stripes that will be required */
    s->stripes = jbg_stripes(s->l0, s->yd);
    
    /* some initialization */
    s->ii = 0;

	s->s = (struct jbg_ardec_state *)checked_malloc(1, sizeof(struct jbg_ardec_state));

	s->lhp[0] = (unsigned char *)checked_malloc(s->yd, jbg_ceil_half(s->xd, 3));
    
	arith_decode_init(s->s, 0);

    s->comment_skip = 0;
    s->buf_len = 0;
    s->x = 0;
    s->i = 0;
    s->pseudo = 1;
    s->at_moves = 0;
  }


  /*
   * BID processing loop
   */
  
  while (*cnt < len) {

    /* process floating marker segments */

    /* skip COMMENT contents */
    if (s->comment_skip) {
      if (s->comment_skip <= len - *cnt) {
	*cnt += s->comment_skip;
	s->comment_skip = 0;
      } else {
	s->comment_skip -= len - *cnt;
	*cnt = len;
      }
      continue;
    }

    /* load complete marker segments into s->buffer for processing */
    if (s->buf_len > 0) {
      assert(s->buffer[0] == MARKER_ESC);
      while (s->buf_len < 2 && *cnt < len)
	s->buffer[s->buf_len++] = data[(*cnt)++];
      if (s->buf_len < 2) continue;
      switch (s->buffer[1]) {
      case MARKER_COMMENT: required_length = 6; break;
      case MARKER_ATMOVE:  required_length = 8; break;
      case MARKER_NEWLEN:  required_length = 6; break;
      case MARKER_ABORT:
      case MARKER_SDNORM:
      case MARKER_SDRST:   required_length = 2; break;
      case MARKER_STUFF:
	/* forward stuffed 0xff to arithmetic decoder */
	s->buf_len = 0;
	decode_pscd(s, s->buffer, 2);
	continue;
      default:
	return JBG_EMARKER;
      }
      while (s->buf_len < required_length && *cnt < len)
	s->buffer[s->buf_len++] = data[(*cnt)++];
      if (s->buf_len < required_length) continue;
      /* now the buffer is filled with exactly one marker segment */
      switch (s->buffer[1]) 
      {
      case MARKER_ATMOVE:
	if (s->at_moves < JBG_ATMOVES_MAX) {
	  s->at_line[s->at_moves] =
	    (((long) s->buffer[2] << 24) | ((long) s->buffer[3] << 16) |
	     ((long) s->buffer[4] <<  8) | (long) s->buffer[5]);
	  s->at_tx[s->at_moves] = (signed char) s->buffer[6];
	  s->at_ty[s->at_moves] = s->buffer[7];
	  if (s->at_tx[s->at_moves] < - (int) s->mx ||
	      s->at_tx[s->at_moves] >   (int) s->mx ||
	      s->at_ty[s->at_moves] >   (int) s->my ||
	      (s->at_ty[s->at_moves] == 0 && s->at_tx[s->at_moves] < 0))
	    return JBG_EINVAL;
	  if (s->at_ty[s->at_moves] != 0)
	    return JBG_EIMPL;
	  s->at_moves++;
	} else
	  return JBG_EIMPL;
	break;

      case MARKER_ABORT:
		return JBG_EABORT;
	
      case MARKER_SDNORM:
      case MARKER_SDRST:
	/* decode final pixels based on trailing zero bytes */
	decode_pscd(s, s->buffer, 2);

	arith_decode_init(s->s, s->ii != s->stripes - 1 && s->buffer[1] != MARKER_SDRST);
	
	s->reset = (s->buffer[1] == MARKER_SDRST);
	
	/* prepare for next SDE */
	s->x = 0;
	s->i = 0;
	s->pseudo = 1;
	s->at_moves = 0;
	
	/* increment layer/stripe/plane loop variables */
	/* start and end value for each loop: */

	if (++s->ii >= s->stripes)
		j = 1;
	else
		j = 0;
	    
	s->buf_len = 0;
	
	/* check whether this have been all SDEs */
	if (j) {
#ifdef DEBUG
	  fprintf(stderr, "This was the final SDE in this BIE, "
		  "%d bytes left.\n", len - *cnt);
#endif
	  s->bie_len = 0;
	  return JBG_EOK;
	}

	break;
	  }
      s->buf_len = 0;

    } else if (data[*cnt] == MARKER_ESC)
      s->buffer[s->buf_len++] = data[(*cnt)++];

    else {

      /* we have found PSCD bytes */
      *cnt += decode_pscd(s, data + *cnt, len - *cnt);
      if (*cnt < len && data[*cnt] != 0xff) {
#ifdef DEBUG
	fprintf(stderr, "PSCD was longer than expected, unread bytes "
		"%02x %02x %02x %02x ...\n", data[*cnt], data[*cnt+1],
		data[*cnt+2], data[*cnt+3]);
#endif
	return JBG_EINVAL;
      }
      
    }
  }  /* of BID processing loop 'while (*cnt < len) ...' */

  return JBG_EAGAIN;
}


/*
 * After jbg_dec_in() returned JBG_EOK or JBG_EOK_INTR, you can call this
 * function in order to find out the width of the image.
 */
long jbg_dec_getwidth(const struct jbg_dec_state *s)
{
  if (s->d < 0)
    return -1;

  if (s->ii < 1)
      return -1;
  else
      return jbg_ceil_half(s->xd, s->d - (s->ii - 1));
}


/*
 * After jbg_dec_in() returned JBG_EOK or JBG_EOK_INTR, you can call this
 * function in order to find out the height of the image.
 */
long jbg_dec_getheight(const struct jbg_dec_state *s)
{
  if (s->d < 0)
    return -1;
  if (s->ii < 1)
     return -1;
  else
     return jbg_ceil_half(s->yd, s->d - (s->ii - 1));
}


/*
 * After jbg_dec_in() returned JBG_EOK or JBG_EOK_INTR, you can call this
 * function in order to get a pointer to the image.
 */
unsigned char *jbg_dec_getimage(const struct jbg_dec_state *s)
{
  if (s->d < 0)
    return NULL;
  if (s->ii < 1)
    return NULL;
  else
    return s->lhp[0];
}


/*
 * After jbg_dec_in() returned JBG_EOK or JBG_EOK_INTR, you can call
 * this function in order to find out the size in bytes of one
 * bitplane of the image.
 */
long jbg_dec_getsize(const struct jbg_dec_state *s)
{
  if (s->d < 0)
    return -1;

  if (s->ii < 1)
      return -1;
  else
      return 
	jbg_ceil_half(s->xd, s->d - (s->ii - 1) + 3) *
	jbg_ceil_half(s->yd, s->d - (s->ii - 1));
}




/* 
 * The destructor function which releases any resources obtained by the
 * other decoder functions.
 */
void jbg_dec_free(struct jbg_dec_state *s)
{
  if (s->d < 0 || s->s == NULL)
    return;
  s->d = -2;
  
  checked_free(s->lhp[0]);
  
  checked_free(s->s);

  s->s = NULL;

  return;
}




/*
 * Given a pointer p to the first byte of either a marker segment or a
 * PSCD, as well as the length len of the remaining data, return
 * either the pointer to the first byte of the next marker segment or
 * PSCD, or p+len if this was the last one, or NULL if some error was
 * encountered.
 */
unsigned char *jbg_next_pscdms(unsigned char *p, size_t len)
{
  unsigned char *pp;
  unsigned long l;

  if (len < 2)
    return NULL;

  if (p[0] != MARKER_ESC || p[1] == MARKER_STUFF) {
    do {
      while (p[0] == MARKER_ESC && p[1] == MARKER_STUFF) {
	p += 2;
	len -= 2;
	if (len < 2) return NULL;
      }
      pp = (unsigned char *) memchr(p, MARKER_ESC, len - 1);
      if (!pp) return NULL;
      l = pp - p;
      assert(l < len);
      p += l;
      len -= l;
    } while (p[1] == MARKER_STUFF);
  } else {
    switch (p[1]) {
    case MARKER_SDNORM:
    case MARKER_SDRST:
    case MARKER_ABORT:
      return p + 2;
    case MARKER_NEWLEN:
      if (len < 6) return NULL;
      return p + 6;
    case MARKER_ATMOVE:
      if (len < 8) return NULL;
      return p + 8;
    case MARKER_COMMENT:
      if (len < 6) return NULL;
      l = (((long) p[2] << 24) | ((long) p[3] << 16) |
	   ((long) p[4] <<  8) |  (long) p[5]);
      if (len - 6 < l) return NULL;
      return p + 6 + l;
    default:
      return NULL;
    }
  }

  return p;
}