Split AudReader from AudLoader and move it to FileFormats

We already separated loading from file format reading for sprites and videos.

OpenRA.Mods.Common/FileFormats/AudReader.cs

@@ -0,0 +1,170 @@
+#region Copyright & License Information
+/*
+ * Copyright 2007-2016 The OpenRA Developers (see AUTHORS)
+ * This file is part of OpenRA, which is free software. It is made
+ * available to you under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version. For more
+ * information, see COPYING.
+ */
+#endregion
+
+using System;
+using System.IO;
+
+namespace OpenRA.Mods.Common.FileFormats
+{
+	[Flags]
+	enum SoundFlags
+	{
+		Stereo = 0x1,
+		_16Bit = 0x2,
+	}
+
+	enum SoundFormat
+	{
+		WestwoodCompressed = 1,
+		ImaAdpcm = 99,
+	}
+
+	struct Chunk
+	{
+		public int CompressedSize;
+		public int OutputSize;
+
+		public static Chunk Read(Stream s)
+		{
+			Chunk c;
+			c.CompressedSize = s.ReadUInt16();
+			c.OutputSize = s.ReadUInt16();
+
+			if (s.ReadUInt32() != 0xdeaf)
+				throw new InvalidDataException("Chunk header is bogus");
+			return c;
+		}
+	}
+
+	public class AudReader
+	{
+		static readonly int[] IndexAdjust = { -1, -1, -1, -1, 2, 4, 6, 8 };
+		static readonly int[] StepTable =
+		{
+			7, 8, 9, 10, 11, 12, 13, 14, 16,
+			17, 19, 21, 23, 25, 28, 31, 34, 37,
+			41, 45, 50, 55, 60, 66, 73, 80, 88,
+			97, 107, 118, 130, 143, 157, 173, 190, 209,
+			230, 253, 279, 307, 337, 371, 408, 449, 494,
+			544, 598, 658, 724, 796, 876, 963, 1060, 1166,
+			1282, 1411, 1552, 1707, 1878, 2066, 2272, 2499, 2749,
+			3024, 3327, 3660, 4026, 4428, 4871, 5358, 5894, 6484,
+			7132, 7845, 8630, 9493, 10442, 11487, 12635, 13899, 15289,
+			16818, 18500, 20350, 22385, 24623, 27086, 29794, 32767
+		};
+
+		static short DecodeSample(byte b, ref int index, ref int current)
+		{
+			var sb = (b & 8) != 0;
+			b &= 7;
+
+			var delta = (StepTable[index] * b) / 4 + StepTable[index] / 8;
+			if (sb) delta = -delta;
+
+			current += delta;
+			if (current > short.MaxValue) current = short.MaxValue;
+			if (current < short.MinValue) current = short.MinValue;
+
+			index += IndexAdjust[b];
+			if (index < 0) index = 0;
+			if (index > 88) index = 88;
+
+			return (short)current;
+		}
+
+		public static byte[] LoadSound(byte[] raw, ref int index)
+		{
+			var s = new MemoryStream(raw);
+			var dataSize = raw.Length;
+			var outputSize = raw.Length * 4;
+
+			var output = new byte[outputSize];
+			var offset = 0;
+			var currentSample = 0;
+
+			while (dataSize-- > 0)
+			{
+				var b = s.ReadUInt8();
+
+				var t = DecodeSample(b, ref index, ref currentSample);
+				output[offset++] = (byte)t;
+				output[offset++] = (byte)(t >> 8);
+
+				t = DecodeSample((byte)(b >> 4), ref index, ref currentSample);
+				output[offset++] = (byte)t;
+				output[offset++] = (byte)(t >> 8);
+			}
+
+			return output;
+		}
+
+		public static float SoundLength(Stream s)
+		{
+			var sampleRate = s.ReadUInt16();
+			/*var dataSize = */ s.ReadInt32();
+			var outputSize = s.ReadInt32();
+			var flags = (SoundFlags)s.ReadByte();
+
+			var samples = outputSize;
+			if (0 != (flags & SoundFlags.Stereo)) samples /= 2;
+			if (0 != (flags & SoundFlags._16Bit)) samples /= 2;
+			return samples / sampleRate;
+		}
+
+		public static bool LoadSound(Stream s, out byte[] rawData, out int sampleRate)
+		{
+			rawData = null;
+
+			sampleRate = s.ReadUInt16();
+			var dataSize = s.ReadInt32();
+			var outputSize = s.ReadInt32();
+
+			var readFlag = s.ReadByte();
+			if (!Enum.IsDefined(typeof(SoundFlags), readFlag))
+				return false;
+
+			var readFormat = s.ReadByte();
+			if (!Enum.IsDefined(typeof(SoundFormat), readFormat))
+				return false;
+
+			var output = new byte[outputSize];
+			var offset = 0;
+			var index = 0;
+			var currentSample = 0;
+
+			while (dataSize > 0)
+			{
+				var chunk = Chunk.Read(s);
+				for (var n = 0; n < chunk.CompressedSize; n++)
+				{
+					var b = s.ReadUInt8();
+
+					var t = DecodeSample(b, ref index, ref currentSample);
+					output[offset++] = (byte)t;
+					output[offset++] = (byte)(t >> 8);
+
+					if (offset < outputSize)
+					{
+						/* possible that only half of the final byte is used! */
+						t = DecodeSample((byte)(b >> 4), ref index, ref currentSample);
+						output[offset++] = (byte)t;
+						output[offset++] = (byte)(t >> 8);
+					}
+				}
+
+				dataSize -= 8 + chunk.CompressedSize;
+			}
+
+			rawData = output;
+			return true;
+		}
+	}
+}