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

				  & entropy->derived_tbls[tbl]);
	}
      } else {
	tbl = compptr->ac_tbl_no;
	jpeg_make_d_derived_tbl(cinfo, FALSE, tbl,
				& entropy->derived_tbls[tbl]);
	/* remember the single active table */
	entropy->ac_derived_tbl = entropy->derived_tbls[tbl];
      }
      /* Initialize DC predictions to 0 */
      entropy->saved.last_dc_val[ci] = 0;
    }

    /* Initialize private state variables */
    entropy->saved.EOBRUN = 0;
  } else {
    /* Check that the scan parameters Ss, Se, Ah/Al are OK for sequential JPEG.
     * This ought to be an error condition, but we make it a warning because
     * there are some baseline files out there with all zeroes in these bytes.
     */
    if (cinfo->Ss != 0 || cinfo->Ah != 0 || cinfo->Al != 0 ||
	((cinfo->is_baseline || cinfo->Se < DCTSIZE2) &&
	cinfo->Se != cinfo->lim_Se))
      WARNMS(cinfo, JWRN_NOT_SEQUENTIAL);

    /* Select MCU decoding routine */
    /* We retain the hard-coded case for full-size blocks.
     * This is not necessary, but it appears that this version is slightly
     * more performant in the given implementation.
     * With an improved implementation we would prefer a single optimized
     * function.
     */
    if (cinfo->lim_Se != DCTSIZE2-1)
      entropy->pub.decode_mcu = decode_mcu_sub;
    else
      entropy->pub.decode_mcu = decode_mcu;

    for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
      compptr = cinfo->cur_comp_info[ci];
      /* Compute derived values for Huffman tables */
      /* We may do this more than once for a table, but it's not expensive */
      tbl = compptr->dc_tbl_no;
      jpeg_make_d_derived_tbl(cinfo, TRUE, tbl,
			      & entropy->dc_derived_tbls[tbl]);
      if (cinfo->lim_Se) {	/* AC needs no table when not present */
	tbl = compptr->ac_tbl_no;
	jpeg_make_d_derived_tbl(cinfo, FALSE, tbl,
				& entropy->ac_derived_tbls[tbl]);
      }
      /* Initialize DC predictions to 0 */
      entropy->saved.last_dc_val[ci] = 0;
    }

    /* Precalculate decoding info for each block in an MCU of this scan */
    for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
      ci = cinfo->MCU_membership[blkn];
      compptr = cinfo->cur_comp_info[ci];
      /* Precalculate which table to use for each block */
      entropy->dc_cur_tbls[blkn] = entropy->dc_derived_tbls[compptr->dc_tbl_no];
      entropy->ac_cur_tbls[blkn] = entropy->ac_derived_tbls[compptr->ac_tbl_no];
      /* Decide whether we really care about the coefficient values */
      if (compptr->component_needed) {
	ci = compptr->DCT_v_scaled_size;
	i = compptr->DCT_h_scaled_size;
	switch (cinfo->lim_Se) {
	case (1*1-1):
	  entropy->coef_limit[blkn] = 1;
	  break;
	case (2*2-1):
	  if (ci <= 0 || ci > 2) ci = 2;
	  if (i <= 0 || i > 2) i = 2;
	  entropy->coef_limit[blkn] = 1 + jpeg_zigzag_order2[ci - 1][i - 1];
	  break;
	case (3*3-1):
	  if (ci <= 0 || ci > 3) ci = 3;
	  if (i <= 0 || i > 3) i = 3;
	  entropy->coef_limit[blkn] = 1 + jpeg_zigzag_order3[ci - 1][i - 1];
	  break;
	case (4*4-1):
	  if (ci <= 0 || ci > 4) ci = 4;
	  if (i <= 0 || i > 4) i = 4;
	  entropy->coef_limit[blkn] = 1 + jpeg_zigzag_order4[ci - 1][i - 1];
	  break;
	case (5*5-1):
	  if (ci <= 0 || ci > 5) ci = 5;
	  if (i <= 0 || i > 5) i = 5;
	  entropy->coef_limit[blkn] = 1 + jpeg_zigzag_order5[ci - 1][i - 1];
	  break;
	case (6*6-1):
	  if (ci <= 0 || ci > 6) ci = 6;
	  if (i <= 0 || i > 6) i = 6;
	  entropy->coef_limit[blkn] = 1 + jpeg_zigzag_order6[ci - 1][i - 1];
	  break;
	case (7*7-1):
	  if (ci <= 0 || ci > 7) ci = 7;
	  if (i <= 0 || i > 7) i = 7;
	  entropy->coef_limit[blkn] = 1 + jpeg_zigzag_order7[ci - 1][i - 1];
	  break;
	default:
	  if (ci <= 0 || ci > 8) ci = 8;
	  if (i <= 0 || i > 8) i = 8;
	  entropy->coef_limit[blkn] = 1 + jpeg_zigzag_order[ci - 1][i - 1];
	  break;
	}
      } else {
	entropy->coef_limit[blkn] = 0;
      }
    }
  }

  /* Initialize bitread state variables */
  entropy->bitstate.bits_left = 0;
  entropy->bitstate.get_buffer = 0; /* unnecessary, but keeps Purify quiet */
  entropy->insufficient_data = FALSE;

  /* Initialize restart counter */
  entropy->restarts_to_go = cinfo->restart_interval;
}


/*