Forgot to optimize guid with span

Author: pl752

src/FirebirdSql.Data.FirebirdClient/Client/Managed/XdrReaderWriter.cs

@@ -299,16 +299,7 @@ public Guid ReadGuid(int sqlType)
 		{
 			Span<byte> buf = stackalloc byte[16];
 			ReadOpaque(buf, 16);
-			var rented = ArrayPool<byte>.Shared.Rent(16);
-			try
-			{
-				buf.CopyTo(rented);
-				return TypeDecoder.DecodeGuid(rented);
-			}
-			finally
-			{
-				ArrayPool<byte>.Shared.Return(rented);
-			}
+			return TypeDecoder.DecodeGuidSpan(buf);
 		}
 	}
 	public async ValueTask<Guid> ReadGuidAsync(int sqlType, CancellationToken cancellationToken = default)

src/FirebirdSql.Data.FirebirdClient/Common/TypeDecoder.cs

@@ -111,6 +111,14 @@ public static Guid DecodeGuid(byte[] value)
 		return new Guid(a, b, c, value[8], value[9], value[10], value[11], value[12], value[13], value[14], value[15]);
 	}
 
+	public static Guid DecodeGuidSpan(Span<byte> value)
+	{
+		var a = IPAddress.HostToNetworkOrder(BitConverter.ToInt32(value[..4]));
+		var b = IPAddress.HostToNetworkOrder(BitConverter.ToInt16(value[4..6]));
+		var c = IPAddress.HostToNetworkOrder(BitConverter.ToInt16(value[6..8]));
+		return new Guid(a, b, c, value[8], value[9], value[10], value[11], value[12], value[13], value[14], value[15]);
+	}
+
 	public static int DecodeInt32(byte[] value)
 	{
 		return IPAddress.HostToNetworkOrder(BitConverter.ToInt32(value, 0));