/**
   * Returns the next code-block in the current tile for the specified component. The order in which
   * code-blocks are returned is not specified. However each code-block is returned only once and
   * all code-blocks will be returned if the method is called 'N' times, where 'N' is the number of
   * code-blocks in the tile. After all the code-blocks have been returned for the current tile
   * calls to this method will return 'null'.
   *
   * <p>When changing the current tile (through 'setTile()' or 'nextTile()') this method will always
   * return the first code-block, as if this method was never called before for the new current
   * tile.
   *
   * <p>The data returned by this method is the data in the internal buffer of this object, and thus
   * can not be modified by the caller. The 'offset' and 'scanw' of the returned data have, in
   * general, some non-zero value. The 'magbits' of the returned data is not set by this method and
   * should be ignored. See the 'CBlkWTData' class.
   *
   * <p>The 'ulx' and 'uly' members of the returned 'CBlkWTData' object contain the coordinates of
   * the top-left corner of the block, with respect to the tile, not the subband.
   *
   * @param c The component for which to return the next code-block.
   * @param cblk If non-null this object will be used to return the new code-block. If null a new
   *     one will be allocated and returned.
   * @return The next code-block in the current tile for component 'n', or null if all code-blocks
   *     for the current tile have been returned.
   * @see CBlkWTData
   */
  public CBlkWTData getNextInternCodeBlock(int c, CBlkWTData cblk) {
    int cbm, cbn, cn, cm;
    int acb0x, acb0y;
    SubbandAn sb;
    intData = (filters.getWTDataType(tIdx, c) == DataBlk.TYPE_INT);

    // If the source image has not been decomposed
    if (decomposedComps[c] == null) {
      int k, w, h;
      DataBlk bufblk;
      Object dst_data;

      w = getTileCompWidth(tIdx, c);
      h = getTileCompHeight(tIdx, c);

      // Get the source image data
      if (intData) {
        decomposedComps[c] = new DataBlkInt(0, 0, w, h);
        bufblk = new DataBlkInt();
      } else {
        decomposedComps[c] = new DataBlkFloat(0, 0, w, h);
        bufblk = new DataBlkFloat();
      }

      // Get data from source line by line (this diminishes the memory
      // requirements on the data source)
      dst_data = decomposedComps[c].getData();
      int lstart = getCompULX(c);
      bufblk.ulx = lstart;
      bufblk.w = w;
      bufblk.h = 1;
      int kk = getCompULY(c);
      for (k = 0; k < h; k++, kk++) {
        bufblk.uly = kk;
        bufblk.ulx = lstart;
        bufblk = src.getInternCompData(bufblk, c);
        System.arraycopy(bufblk.getData(), bufblk.offset, dst_data, k * w, w);
      }

      // Decompose source image
      waveletTreeDecomposition(decomposedComps[c], getAnSubbandTree(tIdx, c), c);

      // Make the first subband the current one
      currentSubband[c] = getNextSubband(c);

      lastn[c] = -1;
      lastm[c] = 0;
    }

    // Get the next code-block to "send"
    do {
      // Calculate number of code-blocks in current subband
      ncblks = currentSubband[c].numCb;
      // Goto next code-block
      lastn[c]++;
      if (lastn[c] == ncblks.x) { // Got to end of this row of
        // code-blocks
        lastn[c] = 0;
        lastm[c]++;
      }
      if (lastm[c] < ncblks.y) {
        // Not past the last code-block in the subband, we can return
        // this code-block
        break;
      }
      // If we get here we already sent all code-blocks in this subband,
      // goto next subband
      currentSubband[c] = getNextSubband(c);
      lastn[c] = -1;
      lastm[c] = 0;
      if (currentSubband[c] == null) {
        // We don't need the transformed data any more (a priori)
        decomposedComps[c] = null;
        // All code-blocks from all subbands in the current
        // tile have been returned so we return a null
        // reference
        return null;
      }
      // Loop to find the next code-block
    } while (true);

    // Project code-block partition origin to subband. Since the origin is
    // always 0 or 1, it projects to the low-pass side (throught the ceil
    // operator) as itself (i.e. no change) and to the high-pass side
    // (through the floor operator) as 0, always.
    acb0x = cb0x;
    acb0y = cb0y;
    switch (currentSubband[c].sbandIdx) {
      case Subband.WT_ORIENT_LL:
        // No need to project since all low-pass => nothing to do
        break;
      case Subband.WT_ORIENT_HL:
        acb0x = 0;
        break;
      case Subband.WT_ORIENT_LH:
        acb0y = 0;
        break;
      case Subband.WT_ORIENT_HH:
        acb0x = 0;
        acb0y = 0;
        break;
      default:
        throw new Error("Internal JJ2000 error");
    }
    // Initialize output code-block
    if (cblk == null) {
      if (intData) {
        cblk = new CBlkWTDataInt();
      } else {
        cblk = new CBlkWTDataFloat();
      }
    }
    cbn = lastn[c];
    cbm = lastm[c];
    sb = currentSubband[c];
    cblk.n = cbn;
    cblk.m = cbm;
    cblk.sb = sb;
    // Calculate the indexes of first code-block in subband with respect
    // to the partitioning origin, to then calculate the position and size
    // NOTE: when calculating "floor()" by integer division the dividend
    // and divisor must be positive, we ensure that by adding the divisor
    // to the dividend and then substracting 1 to the result of the
    // division
    cn = (sb.ulcx - acb0x + sb.nomCBlkW) / sb.nomCBlkW - 1;
    cm = (sb.ulcy - acb0y + sb.nomCBlkH) / sb.nomCBlkH - 1;
    if (cbn == 0) { // Left-most code-block, starts where subband starts
      cblk.ulx = sb.ulx;
    } else {
      // Calculate starting canvas coordinate and convert to subb. coords
      cblk.ulx = (cn + cbn) * sb.nomCBlkW - (sb.ulcx - acb0x) + sb.ulx;
    }
    if (cbm == 0) { // Bottom-most code-block, starts where subband starts
      cblk.uly = sb.uly;
    } else {
      cblk.uly = (cm + cbm) * sb.nomCBlkH - (sb.ulcy - acb0y) + sb.uly;
    }
    if (cbn < ncblks.x - 1) {
      // Calculate where next code-block starts => width
      cblk.w = (cn + cbn + 1) * sb.nomCBlkW - (sb.ulcx - acb0x) + sb.ulx - cblk.ulx;
    } else { // Right-most code-block, ends where subband ends
      cblk.w = sb.ulx + sb.w - cblk.ulx;
    }
    if (cbm < ncblks.y - 1) {
      // Calculate where next code-block starts => height
      cblk.h = (cm + cbm + 1) * sb.nomCBlkH - (sb.ulcy - acb0y) + sb.uly - cblk.uly;
    } else { // Bottom-most code-block, ends where subband ends
      cblk.h = sb.uly + sb.h - cblk.uly;
    }
    cblk.wmseScaling = 1f;

    // Since we are in getNextInternCodeBlock() we can return a
    // reference to the internal buffer, no need to copy. Just initialize
    // the 'offset' and 'scanw'
    cblk.offset = cblk.uly * decomposedComps[c].w + cblk.ulx;
    cblk.scanw = decomposedComps[c].w;

    // For the data just put a reference to our buffer
    cblk.setData(decomposedComps[c].getData());
    // Return code-block
    return cblk;
  }