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src/Source/LibJPEG/jcmaster.c  view on Meta::CPAN

    Ss = scanptr->Ss;
    Se = scanptr->Se;
    Ah = scanptr->Ah;
    Al = scanptr->Al;
    if (cinfo->progressive_mode) {
#ifdef C_PROGRESSIVE_SUPPORTED
      /* The JPEG spec simply gives the ranges 0..13 for Ah and Al, but that
       * seems wrong: the upper bound ought to depend on data precision.
       * Perhaps they really meant 0..N+1 for N-bit precision.
       * Here we allow 0..10 for 8-bit data; Al larger than 10 results in
       * out-of-range reconstructed DC values during the first DC scan,
       * which might cause problems for some decoders.
       */
#if BITS_IN_JSAMPLE == 8
#define MAX_AH_AL 10
#else
#define MAX_AH_AL 13
#endif
      if (Ss < 0 || Ss >= DCTSIZE2 || Se < Ss || Se >= DCTSIZE2 ||
	  Ah < 0 || Ah > MAX_AH_AL || Al < 0 || Al > MAX_AH_AL)
	ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
      if (Ss == 0) {
	if (Se != 0)		/* DC and AC together not OK */
	  ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
      } else {
	if (ncomps != 1)	/* AC scans must be for only one component */
	  ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
      }
      for (ci = 0; ci < ncomps; ci++) {
	last_bitpos_ptr = & last_bitpos[scanptr->component_index[ci]][0];
	if (Ss != 0 && last_bitpos_ptr[0] < 0) /* AC without prior DC scan */
	  ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
	for (coefi = Ss; coefi <= Se; coefi++) {
	  if (last_bitpos_ptr[coefi] < 0) {
	    /* first scan of this coefficient */
	    if (Ah != 0)
	      ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
	  } else {
	    /* not first scan */
	    if (Ah != last_bitpos_ptr[coefi] || Al != Ah-1)
	      ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
	  }
	  last_bitpos_ptr[coefi] = Al;
	}
      }
#endif
    } else {
      /* For sequential JPEG, all progression parameters must be these: */
      if (Ss != 0 || Se != DCTSIZE2-1 || Ah != 0 || Al != 0)
	ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
      /* Make sure components are not sent twice */
      for (ci = 0; ci < ncomps; ci++) {
	thisi = scanptr->component_index[ci];
	if (component_sent[thisi])
	  ERREXIT1(cinfo, JERR_BAD_SCAN_SCRIPT, scanno);
	component_sent[thisi] = TRUE;
      }
    }
  }

  /* Now verify that everything got sent. */
  if (cinfo->progressive_mode) {
#ifdef C_PROGRESSIVE_SUPPORTED
    /* For progressive mode, we only check that at least some DC data
     * got sent for each component; the spec does not require that all bits
     * of all coefficients be transmitted.  Would it be wiser to enforce
     * transmission of all coefficient bits??
     */
    for (ci = 0; ci < cinfo->num_components; ci++) {
      if (last_bitpos[ci][0] < 0)
	ERREXIT(cinfo, JERR_MISSING_DATA);
    }
#endif
  } else {
    for (ci = 0; ci < cinfo->num_components; ci++) {
      if (! component_sent[ci])
	ERREXIT(cinfo, JERR_MISSING_DATA);
    }
  }
}


LOCAL(void)
reduce_script (j_compress_ptr cinfo)
/* Adapt scan script for use with reduced block size;
 * assume that script has been validated before.
 */
{
  jpeg_scan_info * scanptr;
  int idxout, idxin;

  /* Circumvent const declaration for this function */
  scanptr = (jpeg_scan_info *) cinfo->scan_info;
  idxout = 0;

  for (idxin = 0; idxin < cinfo->num_scans; idxin++) {
    /* After skipping, idxout becomes smaller than idxin */
    if (idxin != idxout)
      /* Copy rest of data;
       * note we stay in given chunk of allocated memory.
       */
      scanptr[idxout] = scanptr[idxin];
    if (scanptr[idxout].Ss > cinfo->lim_Se)
      /* Entire scan out of range - skip this entry */
      continue;
    if (scanptr[idxout].Se > cinfo->lim_Se)
      /* Limit scan to end of block */
      scanptr[idxout].Se = cinfo->lim_Se;
    idxout++;
  }

  cinfo->num_scans = idxout;
}

#endif /* C_MULTISCAN_FILES_SUPPORTED */


LOCAL(void)
select_scan_parameters (j_compress_ptr cinfo)
/* Set up the scan parameters for the current scan */
{