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.Game/CryptoUtil.cs

@@ -165,9 +165,9 @@ static int ReadTLVLength(Stream s)
 			if (length < 0x80)
 				return length;
 
-			var data = new byte[4];
-			s.ReadBytes(data, 0, Math.Min(length & 0x7F, 4));
-			return BitConverter.ToInt32(data.ToArray(), 0);
+			Span<byte> data = stackalloc byte[4];
+			s.ReadBytes(data[..Math.Min(length & 0x7F, 4)]);
+			return BitConverter.ToInt32(data);
 		}
 
 		static int TripletFullLength(int dataLength)

OpenRA.Game/FileFormats/Png.cs

@@ -48,7 +48,7 @@ public Png(Stream s)
 			while (true)
 			{
 				var length = IPAddress.NetworkToHostOrder(s.ReadInt32());
-				var type = Encoding.UTF8.GetString(s.ReadBytes(4));
+				var type = s.ReadASCII(4);
 				var content = s.ReadBytes(length);
 				/*var crc = */s.ReadInt32();
 

OpenRA.Game/FileFormats/ReplayMetadata.cs

@@ -47,7 +47,7 @@ public ReplayMetadata(GameInformation info)
 				throw new NotSupportedException($"Metadata version {version} is not supported");
 
 			// Read game info (max 100K limit as a safeguard against corrupted files)
-			var data = fs.ReadString(Encoding.UTF8, 1024 * 100);
+			var data = fs.ReadLengthPrefixedString(Encoding.UTF8, 1024 * 100);
 			GameInfo = GameInformation.Deserialize(data);
 		}
 
@@ -62,7 +62,7 @@ public void Write(BinaryWriter writer)
 			{
 				// Write lobby info data
 				writer.Flush();
-				dataLength += writer.BaseStream.WriteString(Encoding.UTF8, GameInfo.Serialize());
+				dataLength += writer.BaseStream.WriteLengthPrefixedString(Encoding.UTF8, GameInfo.Serialize());
 			}
 
 			// Write total length & end marker

OpenRA.Game/FileSystem/ZipFile.cs

@@ -117,10 +117,7 @@ public ReadWriteZipFile(string filename, bool create = false)
 
 			void Commit()
 			{
-				var pos = pkgStream.Position;
-				pkgStream.Position = 0;
-				File.WriteAllBytes(Name, pkgStream.ReadBytes((int)pkgStream.Length));
-				pkgStream.Position = pos;
+				File.WriteAllBytes(Name, pkgStream.ToArray());
 			}
 
 			public void Update(string filename, byte[] contents)

OpenRA.Game/Network/GameSave.cs

@@ -122,18 +122,18 @@ public GameSave(string filepath)
 				LastSyncFrame = rs.ReadInt32();
 				lastSyncPacket = rs.ReadBytes(Order.SyncHashOrderLength);
 
-				var globalSettings = MiniYaml.FromString(rs.ReadString(Encoding.UTF8, Connection.MaxOrderLength));
+				var globalSettings = MiniYaml.FromString(rs.ReadLengthPrefixedString(Encoding.UTF8, Connection.MaxOrderLength));
 				GlobalSettings = Session.Global.Deserialize(globalSettings[0].Value);
 
-				var slots = MiniYaml.FromString(rs.ReadString(Encoding.UTF8, Connection.MaxOrderLength));
+				var slots = MiniYaml.FromString(rs.ReadLengthPrefixedString(Encoding.UTF8, Connection.MaxOrderLength));
 				Slots = new Dictionary<string, Session.Slot>();
 				foreach (var s in slots)
 				{
 					var slot = Session.Slot.Deserialize(s.Value);
 					Slots.Add(slot.PlayerReference, slot);
 				}
 
-				var slotClients = MiniYaml.FromString(rs.ReadString(Encoding.UTF8, Connection.MaxOrderLength));
+				var slotClients = MiniYaml.FromString(rs.ReadLengthPrefixedString(Encoding.UTF8, Connection.MaxOrderLength));
 				SlotClients = new Dictionary<string, SlotClient>();
 				foreach (var s in slotClients)
 				{
@@ -144,7 +144,7 @@ public GameSave(string filepath)
 				if (rs.Position != traitDataOffset || rs.ReadInt32() != TraitDataMarker)
 					throw new InvalidDataException("Invalid orasav file");
 
-				var traitData = MiniYaml.FromString(rs.ReadString(Encoding.UTF8, Connection.MaxOrderLength));
+				var traitData = MiniYaml.FromString(rs.ReadLengthPrefixedString(Encoding.UTF8, Connection.MaxOrderLength));
 				foreach (var td in traitData)
 					TraitData.Add(Exts.ParseInt32Invariant(td.Key), td.Value);
 
@@ -294,25 +294,25 @@ public void Save(string path)
 				file.Write(lastSyncPacket, 0, Order.SyncHashOrderLength);
 
 				var globalSettingsNodes = new List<MiniYamlNode>() { GlobalSettings.Serialize() };
-				file.WriteString(Encoding.UTF8, globalSettingsNodes.WriteToString());
+				file.WriteLengthPrefixedString(Encoding.UTF8, globalSettingsNodes.WriteToString());
 
 				var slotNodes = Slots
 					.Select(s => s.Value.Serialize())
 					.ToList();
-				file.WriteString(Encoding.UTF8, slotNodes.WriteToString());
+				file.WriteLengthPrefixedString(Encoding.UTF8, slotNodes.WriteToString());
 
 				var slotClientNodes = SlotClients
 					.Select(s => s.Value.Serialize(s.Key))
 					.ToList();
-				file.WriteString(Encoding.UTF8, slotClientNodes.WriteToString());
+				file.WriteLengthPrefixedString(Encoding.UTF8, slotClientNodes.WriteToString());
 
 				var traitDataOffset = file.Length;
 				file.Write(TraitDataMarker);
 
 				var traitDataNodes = TraitData
 					.Select(kv => new MiniYamlNode(kv.Key.ToStringInvariant(), kv.Value))
 					.ToList();
-				file.WriteString(Encoding.UTF8, traitDataNodes.WriteToString());
+				file.WriteLengthPrefixedString(Encoding.UTF8, traitDataNodes.WriteToString());
 
 				file.Write((int)ordersStream.Length);
 				file.Write((int)traitDataOffset);

OpenRA.Game/Network/OrderIO.cs

@@ -86,7 +86,7 @@ public static byte[] SerializeSync((int Frame, int SyncHash, ulong DefeatState)
 			ms.Write(data.Frame);
 			ms.WriteByte((byte)OrderType.SyncHash);
 			ms.Write(data.SyncHash);
-			ms.WriteArray(BitConverter.GetBytes(data.DefeatState));
+			ms.Write(data.DefeatState);
 			return ms.GetBuffer();
 		}
 
@@ -95,7 +95,7 @@ public static byte[] SerializePingResponse(long timestamp, byte queueLength)
 			var ms = new MemoryStream(14);
 			ms.Write(0);
 			ms.WriteByte((byte)OrderType.Ping);
-			ms.WriteArray(BitConverter.GetBytes(timestamp));
+			ms.Write(timestamp);
 			ms.WriteByte(queueLength);
 			return ms.GetBuffer();
 		}

OpenRA.Game/Server/Connection.cs

@@ -64,7 +64,7 @@ static byte[] CreatePingFrame()
 			ms.Write(0);
 			ms.Write(0);
 			ms.WriteByte((byte)OrderType.Ping);
-			ms.WriteArray(BitConverter.GetBytes(Game.RunTime));
+			ms.Write(Game.RunTime);
 			return ms.GetBuffer();
 		}
 

OpenRA.Game/StreamExts.cs

@@ -20,6 +20,17 @@ namespace OpenRA
 {
 	public static class StreamExts
 	{
+		public static void ReadBytes(this Stream s, Span<byte> dest)
+		{
+			while (dest.Length > 0)
+			{
+				var bytesRead = s.Read(dest);
+				if (bytesRead == 0)
+					throw new EndOfStreamException();
+				dest = dest[bytesRead..];
+			}
+		}
+
 		public static byte[] ReadBytes(this Stream s, int count)
 		{
 			if (count < 0)
@@ -35,8 +46,8 @@ public static void ReadBytes(this Stream s, byte[] buffer, int offset, int count
 				throw new ArgumentOutOfRangeException(nameof(count), "Non-negative number required.");
 			while (count > 0)
 			{
-				int bytesRead;
-				if ((bytesRead = s.Read(buffer, offset, count)) == 0)
+				var bytesRead = s.Read(buffer, offset, count);
+				if (bytesRead == 0)
 					throw new EndOfStreamException();
 				offset += bytesRead;
 				count -= bytesRead;
@@ -62,47 +73,79 @@ public static byte ReadUInt8(this Stream s)
 
 		public static ushort ReadUInt16(this Stream s)
 		{
-			return (ushort)(s.ReadUInt8() | s.ReadUInt8() << 8);
+			Span<byte> buffer = stackalloc byte[2];
+			s.ReadBytes(buffer);
+			return BitConverter.ToUInt16(buffer);
 		}
 
 		public static short ReadInt16(this Stream s)
 		{
-			return (short)(s.ReadUInt8() | s.ReadUInt8() << 8);
+			Span<byte> buffer = stackalloc byte[2];
+			s.ReadBytes(buffer);
+			return BitConverter.ToInt16(buffer);
 		}
 
 		public static uint ReadUInt32(this Stream s)
 		{
-			return (uint)(s.ReadUInt8() | s.ReadUInt8() << 8 | s.ReadUInt8() << 16 | s.ReadUInt8() << 24);
+			Span<byte> buffer = stackalloc byte[4];
+			s.ReadBytes(buffer);
+			return BitConverter.ToUInt32(buffer);
 		}
 
 		public static int ReadInt32(this Stream s)
 		{
-			return s.ReadUInt8() | s.ReadUInt8() << 8 | s.ReadUInt8() << 16 | s.ReadUInt8() << 24;
+			Span<byte> buffer = stackalloc byte[4];
+			s.ReadBytes(buffer);
+			return BitConverter.ToInt32(buffer);
 		}
 
 		public static void Write(this Stream s, int value)
 		{
-			s.WriteArray(BitConverter.GetBytes(value));
+			Span<byte> buffer = stackalloc byte[4];
+			BitConverter.TryWriteBytes(buffer, value);
+			s.Write(buffer);
+		}
+
+		public static void Write(this Stream s, long value)
+		{
+			Span<byte> buffer = stackalloc byte[8];
+			BitConverter.TryWriteBytes(buffer, value);
+			s.Write(buffer);
+		}
+
+		public static void Write(this Stream s, ulong value)
+		{
+			Span<byte> buffer = stackalloc byte[8];
+			BitConverter.TryWriteBytes(buffer, value);
+			s.Write(buffer);
 		}
 
 		public static void Write(this Stream s, float value)
 		{
-			s.WriteArray(BitConverter.GetBytes(value));
+			Span<byte> buffer = stackalloc byte[4];
+			BitConverter.TryWriteBytes(buffer, value);
+			s.Write(buffer);
 		}
 
-		public static float ReadFloat(this Stream s)
+		public static float ReadSingle(this Stream s)
 		{
-			return BitConverter.ToSingle(s.ReadBytes(4), 0);
+			Span<byte> buffer = stackalloc byte[4];
+			s.ReadBytes(buffer);
+			return BitConverter.ToSingle(buffer);
 		}
 
 		public static double ReadDouble(this Stream s)
 		{
-			return BitConverter.ToDouble(s.ReadBytes(8), 0);
+			Span<byte> buffer = stackalloc byte[8];
+			s.ReadBytes(buffer);
+			return BitConverter.ToDouble(buffer);
 		}
 
 		public static string ReadASCII(this Stream s, int length)
 		{
-			return new string(Encoding.ASCII.GetChars(s.ReadBytes(length)));
+			Span<byte> buffer = length < 128 ? stackalloc byte[length] : new byte[length];
+			s.ReadBytes(buffer);
+			return Encoding.ASCII.GetString(buffer);
 		}
 
 		public static string ReadASCIIZ(this Stream s)
@@ -111,7 +154,12 @@ public static string ReadASCIIZ(this Stream s)
 			byte b;
 			while ((b = s.ReadUInt8()) != 0)
 				bytes.Add(b);
-			return new string(Encoding.ASCII.GetChars(bytes.ToArray()));
+
+#if NET5_0_OR_GREATER
+			return Encoding.ASCII.GetString(System.Runtime.InteropServices.CollectionsMarshal.AsSpan(bytes));
+#else
+			return Encoding.ASCII.GetString(bytes.ToArray());
+#endif
 		}
 
 		public static string ReadAllText(this Stream s)
@@ -137,11 +185,9 @@ public static byte[] ReadAllBytes(this Stream s)
 			}
 		}
 
-		// Note: renamed from Write() to avoid being aliased by
-		// System.IO.Stream.Write(System.ReadOnlySpan) (which is not implemented in Mono)
 		public static void WriteArray(this Stream s, byte[] data)
 		{
-			s.Write(data, 0, data.Length);
+			s.Write(data);
 		}
 
 		public static IEnumerable<string> ReadAllLines(this Stream s)
@@ -210,19 +256,24 @@ public static IEnumerable<ReadOnlyMemory<char>> ReadAllLinesAsMemory(this Stream
 			}
 		}
 
-		// The string is assumed to be length-prefixed, as written by WriteString()
-		public static string ReadString(this Stream s, Encoding encoding, int maxLength)
+		/// <summary>
+		/// The string is assumed to be length-prefixed, as written by <see cref="WriteLengthPrefixedString"/>.
+		/// </summary>
+		public static string ReadLengthPrefixedString(this Stream s, Encoding encoding, int maxLength)
 		{
 			var length = s.ReadInt32();
 			if (length > maxLength)
 				throw new InvalidOperationException($"The length of the string ({length}) is longer than the maximum allowed ({maxLength}).");
 
-			return encoding.GetString(s.ReadBytes(length));
+			Span<byte> buffer = length < 128 ? stackalloc byte[length] : new byte[length];
+			s.ReadBytes(buffer);
+			return encoding.GetString(buffer);
 		}
 
-		// Writes a length-prefixed string using the specified encoding and returns
-		// the number of bytes written.
-		public static int WriteString(this Stream s, Encoding encoding, string text)
+		/// <summary>
+		/// Writes a length-prefixed string using the specified encoding and returns the number of bytes written.
+		/// </summary>
+		public static int WriteLengthPrefixedString(this Stream s, Encoding encoding, string text)
 		{
 			byte[] bytes;
 

OpenRA.Mods.Cnc/FileFormats/AudReader.cs

@@ -150,6 +150,8 @@ sealed class WestwoodCompressedAudStream : ReadOnlyAdapterStream
 		{
 			readonly int outputSize;
 			int dataSize;
+			byte[] inputBuffer;
+			byte[] outputBuffer;
 
 			public WestwoodCompressedAudStream(Stream stream, int outputSize, int dataSize)
 				: base(stream)
@@ -167,8 +169,10 @@ protected override bool BufferData(Stream baseStream, Queue<byte> data)
 
 				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 @@ protected override bool BufferData(Stream baseStream, Queue<byte> data)
 
 				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 @@ public HvaReader(Stream s, string fileName)
 					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

@@ -208,15 +208,15 @@ void CollectAudioData()
 								rawAudio = stream.ReadBytes((int)length / 2);
 								audio2.WriteArray(rawAudio);
 								if (length % 2 != 0)
-									stream.ReadBytes(2);
+									stream.Position += 2;
 							}
 
 							compressed = type == "SND2";
 							break;
 						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 @@ void LoadFrame()
 						break;
 					default:
 						// Don't parse sound here.
-						stream.ReadBytes((int)length);
+						stream.Position += length;
 						break;
 				}
 
@@ -382,8 +382,7 @@ 0rrrrrgg gggbbbbb
 					// 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";