decode static method

void decode(Uint16List input, int si, int nx, int ox, int ny, int oy, int mx,)

Implementation

static void decode(
    Uint16List input, int si, int nx, int ox, int ny, int oy, int mx) {
  final w14 = (mx < (1 << 14));
  final n = (nx > ny) ? ny : nx;
  var p = 1;
  int p2;

  // Search max level
  while (p <= n) {
    p <<= 1;
  }

  p >>= 1;
  p2 = p;
  p >>= 1;

  final a_b = [0, 0];

  // Hierarchical loop on smaller dimension n
  while (p >= 1) {
    var py = si;
    final ey = si + oy * (ny - p2);
    final oy1 = oy * p;
    final oy2 = oy * p2;
    final ox1 = ox * p;
    final ox2 = ox * p2;
    int i00, i01, i10, i11;

    // Y loop
    for (; py <= ey; py += oy2) {
      var px = py;
      final ex = py + ox * (nx - p2);

      // X loop
      for (; px <= ex; px += ox2) {
        final p01 = px + ox1;
        final p10 = px + oy1;
        final p11 = p10 + ox1;

        // 2D wavelet decoding
        if (w14) {
          wdec14(input[px], input[p10], a_b);
          i00 = a_b[0];
          i10 = a_b[1];

          wdec14(input[p01], input[p11], a_b);
          i01 = a_b[0];
          i11 = a_b[1];

          wdec14(i00, i01, a_b);
          input[px] = a_b[0];
          input[p01] = a_b[1];

          wdec14(i10, i11, a_b);
          input[p10] = a_b[0];
          input[p11] = a_b[1];
        } else {
          wdec16(input[px], input[p10], a_b);
          i00 = a_b[0];
          i10 = a_b[1];

          wdec16(input[p01], input[p11], a_b);
          i01 = a_b[0];
          i11 = a_b[1];

          wdec16(i00, i01, a_b);
          input[px] = a_b[0];
          input[p01] = a_b[1];

          wdec16(i10, i11, a_b);
          input[p10] = a_b[0];
          input[p11] = a_b[1];
        }
      }

      // Decode (1D) odd column (still in Y loop)
      if (nx & p != 0) {
        final p10 = px + oy1;

        if (w14) {
          wdec14(input[px], input[p10], a_b);
          i00 = a_b[0];
          input[p10] = a_b[1];
        } else {
          wdec16(input[px], input[p10], a_b);
          i00 = a_b[0];
          input[p10] = a_b[1];
        }

        input[px] = i00;
      }
    }

    // Decode (1D) odd line (must loop in X)
    if (ny & p != 0) {
      var px = py;
      final ex = py + ox * (nx - p2);

      for (; px <= ex; px += ox2) {
        final p01 = px + ox1;

        if (w14) {
          wdec14(input[px], input[p01], a_b);
          i00 = a_b[0];
          input[p01] = a_b[1];
        } else {
          wdec16(input[px], input[p01], a_b);
          i00 = a_b[0];
          input[p01] = a_b[1];
        }

        input[px] = i00;
      }
    }

    // Next level
    p2 = p;
    p >>= 1;
  }
}