using System;

using System.IO;

using System.Runtime.InteropServices;

using BCnEncoder.Shared;

namespace BCnEncoder.Decoder

{

internal class Bc7Decoder : IBcBlockDecoder

{

public unsafe RawBlock4X4Rgba32[,] Decode(byte[] data, int pixelWidth, int pixelHeight, out int blockWidth, out int blockHeight) {

blockWidth = (int)Math.Ceiling(pixelWidth / 4.0f);

blockHeight = (int)Math.Ceiling(pixelHeight / 4.0f);

if (data.Length != (blockWidth * blockHeight * sizeof(Bc7Block))) {

throw new InvalidDataException();

}

RawBlock4X4Rgba32[,] output = new RawBlock4X4Rgba32[blockWidth, blockHeight];

fixed (byte* iDataBytes = data)

{

Bc7Block* encodedBlocks = (Bc7Block*)iDataBytes;

for (int x = 0; x < blockWidth; x++)

{

for (int y = 0; y < blockHeight; y++)

{

output[x, y] = encodedBlocks[x + y * blockWidth].Decode();

}

}

}

return output;

}

}

}