Implemented WestwoodCompression for AUD files.

OpenRA.Mods.Common/FileFormats/WestwoodCompressedReader.cs

@@ -0,0 +1,86 @@
+#region Copyright & License Information
+
+/*
+ * Copyright 2007-2022 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;
+
+namespace OpenRA.Mods.Common.FileFormats
+{
+	public class WestwoodCompressedReader
+	{
+		static readonly int[] AudWsStepTable2 = { -2, -1, 0, 1 };
+		static readonly int[] AudWsStepTable4 = { -9, -8, -6, -5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5, 6, 8 };
+
+		public static void DecodeWestwoodCompressedSample(byte[] input, byte[] output)
+		{
+			if (input.Length == output.Length)
+			{
+				Array.Copy(input, output, output.Length);
+
+				return;
+			}
+
+			var sample = 0x80;
+			var r = 0;
+			var w = 0;
+
+			while (r < input.Length)
+			{
+				var count = input[r++] & 0x3f;
+
+				switch (input[r - 1] >> 6)
+				{
+					case 0:
+						for (count++; count > 0; count--)
+						{
+							var code = input[r++];
+							output[w++] = (byte)(sample = (sample + AudWsStepTable2[(code >> 0) & 0x03]).Clamp(byte.MinValue, byte.MaxValue));
+							output[w++] = (byte)(sample = (sample + AudWsStepTable2[(code >> 2) & 0x03]).Clamp(byte.MinValue, byte.MaxValue));
+							output[w++] = (byte)(sample = (sample + AudWsStepTable2[(code >> 4) & 0x03]).Clamp(byte.MinValue, byte.MaxValue));
+							output[w++] = (byte)(sample = (sample + AudWsStepTable2[(code >> 6) & 0x03]).Clamp(byte.MinValue, byte.MaxValue));
+						}
+
+						break;
+
+					case 1:
+						for (count++; count > 0; count--)
+						{
+							var code = input[r++];
+							output[w++] = (byte)(sample = (sample + AudWsStepTable4[(code >> 0) & 0x0f]).Clamp(byte.MinValue, byte.MaxValue));
+							output[w++] = (byte)(sample = (sample + AudWsStepTable4[(code >> 4) & 0xff]).Clamp(byte.MinValue, byte.MaxValue));
+						}
+
+						break;
+
+					case 2 when (count & 0x20) != 0:
+						output[w++] = (byte)(sample += (sbyte)((sbyte)count << 3) >> 3);
+
+						break;
+
+					case 2:
+						for (count++; count > 0; count--)
+							output[w++] = input[r++];
+
+						sample = input[r - 1];
+
+						break;
+
+					default:
+						for (count++; count > 0; count--)
+							output[w++] = (byte)sample;
+
+						break;
+				}
+			}
+		}
+	}
+}