Improve loading performance for loader/compression classes.

- In RLEZerosCompression use dedicated Array.Clear method instead of open-coded loop.
- In VoxelLoader.GenerateSlicePlanes.Get use TryGetValue to avoid repeated array and dictionary lookups.
- In TmpTSLoader.UnpackTileData use ReadBytes to populate array with less overhead compared to repeated one byte reads.
- Resolve TODO in VqaVideo.

OpenRA.Mods.Cnc/FileFormats/VqaVideo.cs

@@ -332,7 +332,7 @@ namespace OpenRA.Mods.Cnc.FileFormats
 				if (!cbpIsCompressed)
 					cbf = (byte[])cbp.Clone();
 				else
-					LCWDecodeInto(cbp, cbf);
+					LCWCompression.DecodeInto(cbp, cbf);
 
 				chunkBufferOffset = currentChunkBuffer = 0;
 			}
@@ -352,7 +352,7 @@ namespace OpenRA.Mods.Cnc.FileFormats
 						s.ReadBytes(fileBuffer, 0, subchunkLength);
 						Array.Clear(cbf, 0, cbf.Length);
 						Array.Clear(cbfBuffer, 0, cbfBuffer.Length);
-						var decodeCount = LCWDecodeInto(fileBuffer, cbfBuffer, decodeMode ? 1 : 0, decodeMode);
+						var decodeCount = LCWCompression.DecodeInto(fileBuffer, cbfBuffer, decodeMode ? 1 : 0, decodeMode);
 						if ((videoFlags & 0x10) == 16)
 						{
 							var p = 0;
@@ -406,7 +406,7 @@ namespace OpenRA.Mods.Cnc.FileFormats
 
 					// Frame data
 					case "VPTZ":
-						LCWDecodeInto(s.ReadBytes(subchunkLength), origData);
+						LCWCompression.DecodeInto(s.ReadBytes(subchunkLength), origData);
 
 						// This is the last subchunk
 						return;
@@ -414,9 +414,9 @@ namespace OpenRA.Mods.Cnc.FileFormats
 						Array.Clear(origData, 0, origData.Length);
 						s.ReadBytes(fileBuffer, 0, subchunkLength);
 						if (fileBuffer[0] != 0)
-							vtprSize = LCWDecodeInto(fileBuffer, origData);
+							vtprSize = LCWCompression.DecodeInto(fileBuffer, origData);
 						else
-							LCWDecodeInto(fileBuffer, origData, 1, true);
+							LCWCompression.DecodeInto(fileBuffer, origData, 1, true);
 						return;
 					case "VPTR":
 						Array.Clear(origData, 0, origData.Length);
@@ -541,75 +541,5 @@ namespace OpenRA.Mods.Cnc.FileFormats
 				}
 			}
 		}
-
-		// TODO: Maybe replace this with LCWCompression.DecodeInto again later
-		public static int LCWDecodeInto(byte[] src, byte[] dest, int srcOffset = 0, bool reverse = false)
-		{
-			var ctx = new FastByteReader(src, srcOffset);
-			var destIndex = 0;
-			while (true)
-			{
-				var i = ctx.ReadByte();
-				if ((i & 0x80) == 0)
-				{
-					// case 2
-					var secondByte = ctx.ReadByte();
-					var count = ((i & 0x70) >> 4) + 3;
-					var rpos = ((i & 0xf) << 8) + secondByte;
-
-					if (destIndex + count > dest.Length)
-						return destIndex;
-
-					// Replicate previous
-					var srcIndex = destIndex - rpos;
-					if (srcIndex > destIndex)
-						throw new NotImplementedException($"srcIndex > destIndex {srcIndex} {destIndex}");
-
-					for (var j = 0; j < count; j++)
-					{
-						if (destIndex - srcIndex == 1)
-							dest[destIndex + j] = dest[destIndex - 1];
-						else
-							dest[destIndex + j] = dest[srcIndex + j];
-					}
-
-					destIndex += count;
-				}
-				else if ((i & 0x40) == 0)
-				{
-					// case 1
-					var count = i & 0x3F;
-					if (count == 0)
-						return destIndex;
-
-					ctx.CopyTo(dest, destIndex, count);
-					destIndex += count;
-				}
-				else
-				{
-					var count3 = i & 0x3F;
-					if (count3 == 0x3E)
-					{
-						// case 4
-						var count = ctx.ReadWord();
-						var color = ctx.ReadByte();
-
-						for (var end = destIndex + count; destIndex < end; destIndex++)
-							dest[destIndex] = color;
-					}
-					else
-					{
-						// If count3 == 0x3F it's case 5, else case 3
-						var count = count3 == 0x3F ? ctx.ReadWord() : count3 + 3;
-						var srcIndex = reverse ? destIndex - ctx.ReadWord() : ctx.ReadWord();
-						if (srcIndex >= destIndex)
-							throw new NotImplementedException($"srcIndex >= destIndex {srcIndex} {destIndex}");
-
-						for (var end = destIndex + count; destIndex < end; destIndex++)
-							dest[destIndex] = dest[srcIndex++];
-					}
-				}
-			}
-		}
 	}
 }

OpenRA.Mods.Cnc/Graphics/VoxelLoader.cs

@@ -108,10 +108,10 @@ namespace OpenRA.Mods.Cnc.Graphics
 					return null;
 
 				var v = l.VoxelMap[(byte)x, (byte)y];
-				if (v == null || !v.ContainsKey((byte)z))
+				if (v == null || !v.TryGetValue((byte)z, out var element))
 					return null;
 
-				return l.VoxelMap[(byte)x, (byte)y][(byte)z];
+				return element;
 			}
 
 			// Cull slices without any visible faces

OpenRA.Mods.Cnc/SpriteLoaders/TmpTSLoader.cs

@@ -120,8 +120,7 @@ namespace OpenRA.Mods.Cnc.SpriteLoaders
 			for (var j = 0; j < size.Height; j++)
 			{
 				var start = (j - frameBounds.Y) * frameBounds.Width + (size.Width - width) / 2 - frameBounds.X;
-				for (var i = 0; i < width; i++)
-					data[start + i] = s.ReadUInt8();
+				s.ReadBytes(data, start, width);
 
 				width += (j < size.Height / 2 - 1 ? 1 : -1) * 4;
 			}

OpenRA.Mods.Common/FileFormats/RLEZerosCompression.cs

@@ -9,6 +9,8 @@
  */
 #endregion
 
+using System;
+
 namespace OpenRA.Mods.Common.FileFormats
 {
 	// Run length encoded sequences of zeros (aka Format2)
@@ -24,8 +26,8 @@ namespace OpenRA.Mods.Common.FileFormats
 				if (cmd == 0)
 				{
 					var count = r.ReadByte();
-					while (count-- > 0)
-						dest[destIndex++] = 0;
+					Array.Clear(dest, destIndex, count);
+					destIndex += count;
 				}
 				else
 					dest[destIndex++] = cmd;