Use spans to improve performance in StreamExts.

Also avoid ReadBytes calls that allocate a buffer by either updating the stream position (if not interested in the bytes), by reusing an input buffer (if interested in the bytes), or using a stackalloc buffer to avoid the allocation (for small reads).

OpenRA.Mods.Cnc/FileFormats/AudReader.cs

@@ -150,6 +150,8 @@ namespace OpenRA.Mods.Cnc.FileFormats
 		{
 			readonly int outputSize;
 			int dataSize;
+			byte[] inputBuffer;
+			byte[] outputBuffer;
 
 			public WestwoodCompressedAudStream(Stream stream, int outputSize, int dataSize)
 				: base(stream)
@@ -167,8 +169,10 @@ namespace OpenRA.Mods.Cnc.FileFormats
 
 				var chunk = AudChunk.Read(baseStream);
 
-				var input = baseStream.ReadBytes(chunk.CompressedSize);
-				var output = new byte[chunk.OutputSize];
+				var input = EnsureArraySize(ref inputBuffer, chunk.CompressedSize);
+				var output = EnsureArraySize(ref outputBuffer, chunk.OutputSize);
+
+				baseStream.ReadBytes(input);
 				WestwoodCompressedReader.DecodeWestwoodCompressedSample(input, output);
 
 				foreach (var b in output)
@@ -178,6 +182,13 @@ namespace OpenRA.Mods.Cnc.FileFormats
 
 				return dataSize <= 0;
 			}
+
+			static Span<byte> EnsureArraySize(ref byte[] array, int desiredSize)
+			{
+				if (array == null || array.Length < desiredSize)
+					array = new byte[desiredSize];
+				return array.AsSpan(..desiredSize);
+			}
 		}
 	}
 }

OpenRA.Mods.Cnc/FileFormats/HvaReader.cs

@@ -45,7 +45,7 @@ namespace OpenRA.Mods.Cnc.FileFormats
 					Transforms[c + 15] = 1;
 
 					for (var k = 0; k < 12; k++)
-						Transforms[c + ids[k]] = s.ReadFloat();
+						Transforms[c + ids[k]] = s.ReadSingle();
 
 					Array.Copy(Transforms, 16 * (LimbCount * j + i), testMatrix, 0, 16);
 					if (Util.MatrixInverse(testMatrix) == null)

OpenRA.Mods.Cnc/FileFormats/VqaVideo.cs

@@ -199,16 +199,16 @@ namespace OpenRA.Mods.Cnc.FileFormats
 							else if (AudioChannels == 1)
 							{
 								var rawAudio = stream.ReadBytes((int)length);
-								audio1.WriteArray(rawAudio);
+								audio1.Write(rawAudio);
 							}
 							else
 							{
 								var rawAudio = stream.ReadBytes((int)length / 2);
-								audio1.WriteArray(rawAudio);
+								audio1.Write(rawAudio);
 								rawAudio = stream.ReadBytes((int)length / 2);
-								audio2.WriteArray(rawAudio);
+								audio2.Write(rawAudio);
 								if (length % 2 != 0)
-									stream.ReadBytes(2);
+									stream.Position += 2;
 							}
 
 							compressed = type == "SND2";
@@ -216,7 +216,7 @@ namespace OpenRA.Mods.Cnc.FileFormats
 						default:
 							if (length + stream.Position > stream.Length)
 								throw new NotSupportedException($"Vqa uses unknown Subtype: {type}");
-							stream.ReadBytes((int)length);
+							stream.Position += length;
 							break;
 					}
 
@@ -308,7 +308,7 @@ namespace OpenRA.Mods.Cnc.FileFormats
 						break;
 					default:
 						// Don't parse sound here.
-						stream.ReadBytes((int)length);
+						stream.Position += length;
 						break;
 				}
 
@@ -382,8 +382,7 @@ namespace OpenRA.Mods.Cnc.FileFormats
 					// frame-modifier chunk
 					case "CBP0":
 					case "CBPZ":
-						var bytes = s.ReadBytes(subchunkLength);
-						bytes.CopyTo(cbp, chunkBufferOffset);
+						s.ReadBytes(cbp, chunkBufferOffset, subchunkLength);
 						chunkBufferOffset += subchunkLength;
 						currentChunkBuffer++;
 						cbpIsCompressed = type == "CBPZ";

OpenRA.Mods.Cnc/FileFormats/VxlReader.cs

@@ -141,12 +141,12 @@ namespace OpenRA.Mods.Cnc.FileFormats
 			{
 				limbDataOffset[i] = s.ReadUInt32();
 				s.Seek(8, SeekOrigin.Current);
-				Limbs[i].Scale = s.ReadFloat();
+				Limbs[i].Scale = s.ReadSingle();
 				s.Seek(48, SeekOrigin.Current);
 
 				Limbs[i].Bounds = new float[6];
 				for (var j = 0; j < 6; j++)
-					Limbs[i].Bounds[j] = s.ReadFloat();
+					Limbs[i].Bounds[j] = s.ReadSingle();
 				Limbs[i].Size = s.ReadBytes(3);
 				Limbs[i].Type = (NormalType)s.ReadUInt8();
 			}