package org.jcodec.scale;

import org.jcodec.common.model.Picture;
import org.jcodec.common.tools.MathUtil;

public class Yuv420jToRgb implements Transform {
  private static final int SCALEBITS = 10;
  
  private static final int ONE_HALF = 512;
  
  public final void transform(Picture src, Picture dst) {
    byte[] y = src.getPlaneData(0);
    byte[] u = src.getPlaneData(1);
    byte[] v = src.getPlaneData(2);
    byte[] data = dst.getPlaneData(0);
    int offLuma = 0, offChroma = 0;
    int stride = dst.getWidth();
    for (int i = 0; i < dst.getHeight() >> 1; i++) {
      for (int k = 0; k < dst.getWidth() >> 1; k++) {
        int j = k << 1;
        YUVJtoRGB(y[offLuma + j], u[offChroma], v[offChroma], data, (offLuma + j) * 3);
        YUVJtoRGB(y[offLuma + j + 1], u[offChroma], v[offChroma], data, (offLuma + j + 1) * 3);
        YUVJtoRGB(y[offLuma + j + stride], u[offChroma], v[offChroma], data, (offLuma + j + stride) * 3);
        YUVJtoRGB(y[offLuma + j + stride + 1], u[offChroma], v[offChroma], data, (offLuma + j + stride + 1) * 3);
        offChroma++;
      } 
      if ((dst.getWidth() & 0x1) != 0) {
        int j = dst.getWidth() - 1;
        YUVJtoRGB(y[offLuma + j], u[offChroma], v[offChroma], data, (offLuma + j) * 3);
        YUVJtoRGB(y[offLuma + j + stride], u[offChroma], v[offChroma], data, (offLuma + j + stride) * 3);
        offChroma++;
      } 
      offLuma += 2 * stride;
    } 
    if ((dst.getHeight() & 0x1) != 0) {
      for (int k = 0; k < dst.getWidth() >> 1; k++) {
        int j = k << 1;
        YUVJtoRGB(y[offLuma + j], u[offChroma], v[offChroma], data, (offLuma + j) * 3);
        YUVJtoRGB(y[offLuma + j + 1], u[offChroma], v[offChroma], data, (offLuma + j + 1) * 3);
        offChroma++;
      } 
      if ((dst.getWidth() & 0x1) != 0) {
        int j = dst.getWidth() - 1;
        YUVJtoRGB(y[offLuma + j], u[offChroma], v[offChroma], data, (offLuma + j) * 3);
        offChroma++;
      } 
    } 
  }
  
  private static final int FIX(double x) {
    return (int)(x * 1024.0D + 0.5D);
  }
  
  private static final int FIX_0_71414 = FIX(0.71414D);
  
  private static final int FIX_1_772 = FIX(1.772D);
  
  private static final int _FIX_0_34414 = -FIX(0.34414D);
  
  private static final int FIX_1_402 = FIX(1.402D);
  
  public static final void YUVJtoRGB(byte y, byte cb, byte cr, byte[] data, int off) {
    int y_ = y + 128 << 10;
    int add_r = FIX_1_402 * cr + 512;
    int add_g = _FIX_0_34414 * cb - FIX_0_71414 * cr + 512;
    int add_b = FIX_1_772 * cb + 512;
    int r = y_ + add_r >> 10;
    int g = y_ + add_g >> 10;
    int b = y_ + add_b >> 10;
    data[off] = (byte)MathUtil.clip(r - 128, -128, 127);
    data[off + 1] = (byte)MathUtil.clip(g - 128, -128, 127);
    data[off + 2] = (byte)MathUtil.clip(b - 128, -128, 127);
  }
}