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

OpenRA.Game/FileFormats/Png.cs

@@ -48,7 +48,7 @@ namespace OpenRA.FileFormats
 			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();
 
@@ -287,10 +287,10 @@ namespace OpenRA.FileFormats
 
 			var typeBytes = Encoding.ASCII.GetBytes(type);
 			output.Write(IPAddress.HostToNetworkOrder((int)input.Length));
-			output.WriteArray(typeBytes);
+			output.Write(typeBytes);
 
 			var data = input.ReadAllBytes();
-			output.WriteArray(data);
+			output.Write(data);
 
 			var crc32 = new Crc32();
 			crc32.Update(typeBytes);
@@ -302,7 +302,7 @@ namespace OpenRA.FileFormats
 		{
 			using (var output = new MemoryStream())
 			{
-				output.WriteArray(Signature);
+				output.Write(Signature);
 				using (var header = new MemoryStream())
 				{
 					header.Write(IPAddress.HostToNetworkOrder(Width));
@@ -371,7 +371,7 @@ namespace OpenRA.FileFormats
 				{
 					using (var text = new MemoryStream())
 					{
-						text.WriteArray(Encoding.ASCII.GetBytes(kv.Key + (char)0 + kv.Value));
+						text.Write(Encoding.ASCII.GetBytes(kv.Key + (char)0 + kv.Value));
 						WritePngChunk(output, "tEXt", text);
 					}
 				}

OpenRA.Game/FileFormats/ReplayMetadata.cs

@@ -47,7 +47,7 @@ namespace OpenRA.FileFormats
 				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 @@ namespace OpenRA.FileFormats
 			{
 				// 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 @@ namespace OpenRA.FileSystem
 
 			void Commit()
 			{
-				var pos = pkgStream.Position;
+				File.WriteAllBytes(Name, pkgStream.ToArray());
-				pkgStream.Position = 0;
-				File.WriteAllBytes(Name, pkgStream.ReadBytes((int)pkgStream.Length));
-				pkgStream.Position = pos;
 			}
 
 			public void Update(string filename, byte[] contents)

OpenRA.Game/Network/Connection.cs

@@ -261,14 +261,14 @@ namespace OpenRA.Network
 			{
 				var ms = new MemoryStream();
 				ms.Write(packet.Length);
-				ms.WriteArray(packet);
+				ms.Write(packet);
 
 				foreach (var s in queuedSyncPackets)
 				{
 					var q = OrderIO.SerializeSync(s);
 
 					ms.Write(q.Length);
-					ms.WriteArray(q);
+					ms.Write(q);
 
 					sentSync.Enqueue(s);
 				}

OpenRA.Game/Network/GameSave.cs

@@ -122,10 +122,10 @@ namespace OpenRA.Network
 				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)
 				{
@@ -133,7 +133,7 @@ namespace OpenRA.Network
 					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 @@ namespace OpenRA.Network
 				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);
 
@@ -229,7 +229,7 @@ namespace OpenRA.Network
 			ordersStream.Write(data.Length + 8);
 			ordersStream.Write(frame);
 			ordersStream.Write(clientSlot);
-			ordersStream.WriteArray(data);
+			ordersStream.Write(data);
 			LastOrdersFrame = frame;
 		}
 
@@ -294,17 +294,17 @@ namespace OpenRA.Network
 				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);
@@ -312,7 +312,7 @@ namespace OpenRA.Network
 				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

@@ -27,7 +27,7 @@ namespace OpenRA.Network
 			// the Order objects directly on the local client.
 			data = new MemoryStream();
 			foreach (var o in orders)
-				data.WriteArray(o.Serialize());
+				data.Write(o.Serialize());
 		}
 
 		public OrderPacket(MemoryStream data)
@@ -86,7 +86,7 @@ namespace OpenRA.Network
 			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 @@ namespace OpenRA.Network
 			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/Network/ReplayRecorder.cs

@@ -67,7 +67,7 @@ namespace OpenRA.Network
 				}
 			}
 
-			file.WriteArray(initialContent);
+			file.Write(initialContent);
 			writer = new BinaryWriter(file);
 		}
 
@@ -93,7 +93,7 @@ namespace OpenRA.Network
 		{
 			var ms = new MemoryStream(4 + data.Length);
 			ms.Write(frame);
-			ms.WriteArray(data);
+			ms.Write(data);
 			Receive(clientID, ms.GetBuffer());
 		}
 

OpenRA.Game/Server/Connection.cs

@@ -64,7 +64,7 @@ namespace OpenRA.Server
 			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/Server/Server.cs

@@ -707,7 +707,7 @@ namespace OpenRA.Server
 			ms.Write(data.Length + 4);
 			ms.Write(client);
 			ms.Write(frame);
-			ms.WriteArray(data);
+			ms.Write(data);
 			return ms.GetBuffer();
 		}
 

OpenRA.Game/StreamExts.cs

@@ -20,10 +20,23 @@ 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)
 				throw new ArgumentOutOfRangeException(nameof(count), "Non-negative number required.");
+
 			var buffer = new byte[count];
 			s.ReadBytes(buffer, 0, count);
 			return buffer;
@@ -33,10 +46,11 @@ namespace OpenRA
 		{
 			if (count < 0)
 				throw new ArgumentOutOfRangeException(nameof(count), "Non-negative number required.");
+
 			while (count > 0)
 			{
-				int bytesRead;
+				var bytesRead = s.Read(buffer, offset, count);
-				if ((bytesRead = s.Read(buffer, offset, count)) == 0)
+				if (bytesRead == 0)
 					throw new EndOfStreamException();
 				offset += bytesRead;
 				count -= bytesRead;
@@ -48,6 +62,7 @@ namespace OpenRA
 			var b = s.ReadByte();
 			if (b == -1)
 				return -1;
+
 			s.Seek(-1, SeekOrigin.Current);
 			return (byte)b;
 		}
@@ -57,52 +72,85 @@ namespace OpenRA
 			var b = s.ReadByte();
 			if (b == -1)
 				throw new EndOfStreamException();
+
 			return (byte)b;
 		}
 
 		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 +159,12 @@ namespace OpenRA
 			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)
@@ -133,17 +186,11 @@ namespace OpenRA
 				int count;
 				while ((count = s.Read(buffer, 0, buffer.Length)) > 0)
 					bytes.AddRange(buffer.Take(count));
+
 				return bytes.ToArray();
 			}
 		}
 
-		// 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);
-		}
-
 		public static IEnumerable<string> ReadAllLines(this Stream s)
 		{
 			string line;
@@ -210,19 +257,24 @@ namespace OpenRA
 			}
 		}
 
-		// The string is assumed to be length-prefixed, as written by WriteString()
+		/// <summary>
-		public static string ReadString(this Stream s, Encoding encoding, int maxLength)
+		/// 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
+		/// <summary>
-		// the number of bytes written.
+		/// 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>
+		public static int WriteLengthPrefixedString(this Stream s, Encoding encoding, string text)
 		{
 			byte[] bytes;
 
@@ -232,7 +284,7 @@ namespace OpenRA
 				bytes = Array.Empty<byte>();
 
 			s.Write(bytes.Length);
-			s.WriteArray(bytes);
+			s.Write(bytes);
 
 			return 4 + bytes.Length;
 		}

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 input = EnsureArraySize(ref inputBuffer, chunk.CompressedSize);
-				var output = new byte[chunk.OutputSize];
+				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);
+						s.ReadBytes(cbp, chunkBufferOffset, subchunkLength);
-						bytes.CopyTo(cbp, chunkBufferOffset);
 						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();
 			}

OpenRA.Mods.Common/AudioLoaders/OggLoader.cs

@@ -76,9 +76,7 @@ namespace OpenRA.Mods.Common.AudioLoaders
 		{
 			readonly OggFormat format;
 
-			// This buffer can be static because it can only be used by 1 instance per thread.
+			float[] conversionBuffer;
-			[ThreadStatic]
-			static float[] conversionBuffer;
 
 			public OggStream(OggFormat format)
 			{
@@ -105,13 +103,10 @@ namespace OpenRA.Mods.Common.AudioLoaders
 				// Make sure we don't have an odd count.
 				count -= count % format.reader.Channels;
 
-				// Get the buffer, creating a new one if none exists or the existing one is too small.
+				var floatBuffer = EnsureArraySize(ref conversionBuffer, count);
-				var floatBuffer = conversionBuffer ??= new float[count];
-				if (floatBuffer.Length < count)
-					floatBuffer = conversionBuffer = new float[count];
 
 				// Let NVorbis do the actual reading.
-				var samples = format.reader.ReadSamples(floatBuffer, offset, count);
+				var samples = format.reader.ReadSamples(floatBuffer);
 
 				// Move the data back to the request buffer and convert to 16-bit signed samples for OpenAL.
 				for (var i = 0; i < samples; i++)
@@ -137,6 +132,13 @@ namespace OpenRA.Mods.Common.AudioLoaders
 
 				base.Dispose(disposing);
 			}
+
+			static Span<float> EnsureArraySize(ref float[] array, int desiredSize)
+			{
+				if (array == null || array.Length < desiredSize)
+					array = new float[desiredSize];
+				return array.AsSpan(..desiredSize);
+			}
 		}
 	}
 }

OpenRA.Mods.Common/FileFormats/ImaAdpcmReader.cs

@@ -9,7 +9,7 @@
  */
 #endregion
 
-using System.IO;
+using System;
 
 namespace OpenRA.Mods.Common.FileFormats
 {
@@ -56,15 +56,14 @@ namespace OpenRA.Mods.Common.FileFormats
 			return (short)current;
 		}
 
-		public static byte[] LoadImaAdpcmSound(byte[] raw, ref int index)
+		public static byte[] LoadImaAdpcmSound(ReadOnlySpan<byte> raw, ref int index)
 		{
 			var currentSample = 0;
 			return LoadImaAdpcmSound(raw, ref index, ref currentSample);
 		}
 
-		public static byte[] LoadImaAdpcmSound(byte[] raw, ref int index, ref int currentSample)
+		public static byte[] LoadImaAdpcmSound(ReadOnlySpan<byte> raw, ref int index, ref int currentSample)
 		{
-			var s = new MemoryStream(raw);
 			var dataSize = raw.Length;
 			var outputSize = raw.Length * 4;
 
@@ -73,7 +72,7 @@ namespace OpenRA.Mods.Common.FileFormats
 
 			while (dataSize-- > 0)
 			{
-				var b = s.ReadUInt8();
+				var b = raw[offset / 4];
 
 				var t = DecodeImaAdpcmSample(b, ref index, ref currentSample);
 				output[offset++] = (byte)t;

OpenRA.Mods.Common/FileFormats/WavReader.cs

@@ -67,12 +67,12 @@ namespace OpenRA.Mods.Common.FileFormats
 						blockAlign = s.ReadInt16();
 						sampleBits = s.ReadInt16();
 						lengthInSeconds = (float)(s.Length * 8) / (channels * sampleRate * sampleBits);
-						s.ReadBytes(fmtChunkSize - 16);
+						s.Position += fmtChunkSize - 16;
 						break;
 					case "fact":
 						var chunkSize = s.ReadInt32();
 						uncompressedSize = s.ReadInt32();
-						s.ReadBytes(chunkSize - 4);
+						s.Position += chunkSize - 4;
 						break;
 					case "data":
 						dataSize = s.ReadInt32();
@@ -82,7 +82,7 @@ namespace OpenRA.Mods.Common.FileFormats
 					case "LIST":
 					case "cue ":
 						var listCueChunkSize = s.ReadInt32();
-						s.ReadBytes(listCueChunkSize);
+						s.Position += listCueChunkSize;
 						break;
 					default:
 						s.Position = s.Length; // Skip to end of stream
@@ -156,12 +156,13 @@ namespace OpenRA.Mods.Common.FileFormats
 
 				// Decode and output remaining data in this block
 				var blockOffset = 0;
+				Span<byte> chunk = stackalloc byte[4];
 				while (blockOffset < blockDataSize)
 				{
 					for (var c = 0; c < channels; c++)
 					{
 						// Decode 4 bytes (to 16 bytes of output) per channel
-						var chunk = baseStream.ReadBytes(4);
+						baseStream.ReadBytes(chunk);
 						var decoded = ImaAdpcmReader.LoadImaAdpcmSound(chunk, ref index[c], ref predictor[c]);
 
 						// Interleave output, one sample per channel

OpenRA.Mods.Common/FileFormats/WestwoodCompressedReader.cs

@@ -20,11 +20,11 @@ namespace OpenRA.Mods.Common.FileFormats
 		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)
+		public static void DecodeWestwoodCompressedSample(ReadOnlySpan<byte> input, Span<byte> output)
 		{
 			if (input.Length == output.Length)
 			{
-				Array.Copy(input, output, output.Length);
+				input.CopyTo(output);
 
 				return;
 			}

OpenRA.Mods.Common/FileSystem/InstallShieldPackage.cs

@@ -73,7 +73,7 @@ namespace OpenRA.Mods.Common.FileSystem
 						var dirName = s.ReadASCII(nameLength);
 
 						// Skip to the end of the chunk
-						s.ReadBytes(chunkSize - nameLength - 6);
+						s.Position += chunkSize - nameLength - 6;
 						directories.Add(dirName, fileCount);
 					}