using Ryujinx.Graphics.Texture.Utils; using System.Diagnostics; using System; using System.Numerics; using System.Runtime.InteropServices; namespace Ryujinx.Graphics.Texture { static class BC7Decoder { public static void Decode(Span<byte> output, ReadOnlySpan<byte> data, int width, int height) { ReadOnlySpan<Block> blocks = MemoryMarshal.Cast<byte, Block>(data); Span<uint> output32 = MemoryMarshal.Cast<byte, uint>(output); int wInBlocks = (width + 3) / 4; int hInBlocks = (height + 3) / 4; for (int y = 0; y < hInBlocks; y++) { int y2 = y * 4; int bh = Math.Min(4, height - y2); for (int x = 0; x < wInBlocks; x++) { int x2 = x * 4; int bw = Math.Min(4, width - x2); DecodeBlock(blocks[y * wInBlocks + x], output32.Slice(y2 * width + x2), bw, bh, width); } } } private static void DecodeBlock(Block block, Span<uint> output, int w, int h, int width) { int mode = BitOperations.TrailingZeroCount((byte)block.Low | 0x100); if (mode == 8) { // Mode is invalid, the spec mandates that hardware fills the block with // a transparent black color. for (int ty = 0; ty < h; ty++) { int baseOffs = ty * width; for (int tx = 0; tx < w; tx++) { int offs = baseOffs + tx; output[offs] = 0; } } return; } BC7ModeInfo modeInfo = BC67Tables.BC7ModeInfos[mode]; int offset = mode + 1; int partition = (int)block.Decode(ref offset, modeInfo.PartitionBitCount); int rotation = (int)block.Decode(ref offset, modeInfo.RotationBitCount); int indexMode = (int)block.Decode(ref offset, modeInfo.IndexModeBitCount); Debug.Assert(partition < 64); Debug.Assert(rotation < 4); Debug.Assert(indexMode < 2); int endPointCount = modeInfo.SubsetCount * 2; Span<RgbaColor32> endPoints = stackalloc RgbaColor32[endPointCount]; Span<byte> pValues = stackalloc byte[modeInfo.PBits]; endPoints.Fill(new RgbaColor32(0, 0, 0, 255)); for (int i = 0; i < endPointCount; i++) { endPoints[i].R = (int)block.Decode(ref offset, modeInfo.ColorDepth); } for (int i = 0; i < endPointCount; i++) { endPoints[i].G = (int)block.Decode(ref offset, modeInfo.ColorDepth); } for (int i = 0; i < endPointCount; i++) { endPoints[i].B = (int)block.Decode(ref offset, modeInfo.ColorDepth); } if (modeInfo.AlphaDepth != 0) { for (int i = 0; i < endPointCount; i++) { endPoints[i].A = (int)block.Decode(ref offset, modeInfo.AlphaDepth); } } for (int i = 0; i < modeInfo.PBits; i++) { pValues[i] = (byte)block.Decode(ref offset, 1); } for (int i = 0; i < endPointCount; i++) { int pBit = -1; if (modeInfo.PBits != 0) { int pIndex = (i * modeInfo.PBits) / endPointCount; pBit = pValues[pIndex]; } Unquantize(ref endPoints[i], modeInfo.ColorDepth, modeInfo.AlphaDepth, pBit); } byte[] partitionTable = BC67Tables.PartitionTable[modeInfo.SubsetCount - 1][partition]; byte[] fixUpTable = BC67Tables.FixUpIndices[modeInfo.SubsetCount - 1][partition]; Span<byte> colorIndices = stackalloc byte[16]; for (int i = 0; i < 16; i++) { byte subset = partitionTable[i]; int bitCount = i == fixUpTable[subset] ? modeInfo.ColorIndexBitCount - 1 : modeInfo.ColorIndexBitCount; colorIndices[i] = (byte)block.Decode(ref offset, bitCount); Debug.Assert(colorIndices[i] < 16); } Span<byte> alphaIndices = stackalloc byte[16]; if (modeInfo.AlphaIndexBitCount != 0) { for (int i = 0; i < 16; i++) { int bitCount = i != 0 ? modeInfo.AlphaIndexBitCount : modeInfo.AlphaIndexBitCount - 1; alphaIndices[i] = (byte)block.Decode(ref offset, bitCount); Debug.Assert(alphaIndices[i] < 16); } } for (int ty = 0; ty < h; ty++) { int baseOffs = ty * width; for (int tx = 0; tx < w; tx++) { int i = ty * 4 + tx; RgbaColor32 color; byte subset = partitionTable[i]; RgbaColor32 color1 = endPoints[subset * 2]; RgbaColor32 color2 = endPoints[subset * 2 + 1]; if (modeInfo.AlphaIndexBitCount != 0) { if (indexMode == 0) { color = BC67Utils.Interpolate(color1, color2, colorIndices[i], alphaIndices[i], modeInfo.ColorIndexBitCount, modeInfo.AlphaIndexBitCount); } else { color = BC67Utils.Interpolate(color1, color2, alphaIndices[i], colorIndices[i], modeInfo.AlphaIndexBitCount, modeInfo.ColorIndexBitCount); } } else { color = BC67Utils.Interpolate(color1, color2, colorIndices[i], colorIndices[i], modeInfo.ColorIndexBitCount, modeInfo.ColorIndexBitCount); } if (rotation != 0) { int a = color.A; switch (rotation) { case 1: color.A = color.R; color.R = a; break; case 2: color.A = color.G; color.G = a; break; case 3: color.A = color.B; color.B = a; break; } } RgbaColor8 color8 = color.GetColor8(); output[baseOffs + tx] = color8.ToUInt32(); } } } private static void Unquantize(ref RgbaColor32 color, int colorDepth, int alphaDepth, int pBit) { color.R = UnquantizeComponent(color.R, colorDepth, pBit); color.G = UnquantizeComponent(color.G, colorDepth, pBit); color.B = UnquantizeComponent(color.B, colorDepth, pBit); color.A = alphaDepth != 0 ? UnquantizeComponent(color.A, alphaDepth, pBit) : 255; } private static int UnquantizeComponent(int component, int bits, int pBit) { int shift = 8 - bits; int value = component << shift; if (pBit >= 0) { Debug.Assert(pBit <= 1); value |= value >> (bits + 1); value |= pBit << (shift - 1); } else { value |= value >> bits; } return value; } } }