hack for fp-determinism across Unity and .NET 8

akopetsch · Jun 21, 2024 · 0b0b37c · 0b0b37c
1 parent 2fb08ff
commit 0b0b37c
Show file tree

Hide file tree

Showing 5 changed files with 55 additions and 5 deletions.
diff --git a/ByteSerialization.Tests/Unit/IO/EndianBinaryReaderTest.cs b/ByteSerialization.Tests/Unit/IO/EndianBinaryReaderTest.cs
@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: MIT
+
+using ByteSerialization.IO;
+using Xunit;
+
+namespace ByteSerialization.Tests.Unit.IO
+{
+    public class EndianBinaryReaderTest
+    {
+        [Fact]
+        public void Test_ReadSingle_BE() =>
+            AssertReadResult(13.5407705f, "4158 a6ff", Endianness.BigEndian, r => r.ReadSingle());
+
+        private void AssertReadResult<T>(T expectedValue, string hexStringToRead, Endianness endianness, Func<EndianBinaryReader, T> readFunc)
+        {
+            using var ms = new MemoryStream(HexStringConverter.ToByteArray(hexStringToRead));
+            using var reader = new EndianBinaryReader(ms, endianness);
+            T actualValue = readFunc.Invoke(reader);
+            Assert.Equal(expectedValue, actualValue);
+        }
+    }
+}
diff --git a/ByteSerialization.Tests/Unit/IO/EndianBinaryWriterTest.cs b/ByteSerialization.Tests/Unit/IO/EndianBinaryWriterTest.cs
@@ -0,0 +1,24 @@
+// SPDX-License-Identifier: MIT
+
+using ByteSerialization.IO;
+using Xunit;
+
+namespace ByteSerialization.Tests.Unit.IO
+{
+    public class EndianBinaryWriterTest
+    {
+        [Fact]
+        public void Test_WriteSingle_BE() =>
+            AssertWriteResult("4158 a6ff", 13.5407705f, Endianness.BigEndian, (r, x) => r.Write(x));
+
+        private void AssertWriteResult<T>(string expectedHexString, T valueToWrite, Endianness endianness, Action<EndianBinaryWriter, T> writeFunc)
+        {
+            using var ms = new MemoryStream();
+            using var writer = new EndianBinaryWriter(ms, endianness);
+            writeFunc.Invoke(writer, valueToWrite);
+            byte[] actualBytes = ms.ToArray();
+            byte[] expectedBytes = HexStringConverter.ToByteArray(expectedHexString);
+            Assert.True(Enumerable.SequenceEqual(expectedBytes, actualBytes));
+        }
+    }
+}
diff --git a/ByteSerialization/ByteSerialization.csproj b/ByteSerialization/ByteSerialization.csproj
@@ -5,7 +5,7 @@
     <Nullable>disable</Nullable>
     <Authors>Alexander Kopetsch</Authors>
     <Version>0.0.1.0</Version>
-    <PackageVersion>0.0.1-alpha.8</PackageVersion>
+    <PackageVersion>0.0.1-alpha.9</PackageVersion>
     <PackageProjectUrl>https://github.com/akopetsch/ByteSerialization</PackageProjectUrl>
     <PackageReadmeFile>README.md</PackageReadmeFile>
     <PackageLicenseExpression>MIT</PackageLicenseExpression>

diff --git a/ByteSerialization/IO/EndianBinaryReader.cs b/ByteSerialization/IO/EndianBinaryReader.cs
@@ -112,10 +112,12 @@ public ulong ReadUInt64() =>
             BytesSwapper.SwapIf(_reader.ReadUInt64(), IsBigEndian);
 
         public float ReadSingle() =>
-            BytesSwapper.SwapIf(_reader.ReadSingle(), IsBigEndian);
+            BitConverter.Int32BitsToSingle(BytesSwapper.SwapIf(_reader.ReadInt32(), IsBigEndian));
+        // HACK: regular ``BytesSwapper.SwapIf(_reader.ReadSingle(), IsBigEndian);`` is not deterministic across .NET 8 and Unity 2022.3.30f1 (LTS)
 
         public double ReadDouble() =>
-            BytesSwapper.SwapIf(_reader.ReadDouble(), IsBigEndian);
+            BitConverter.Int64BitsToDouble(BytesSwapper.SwapIf(_reader.ReadInt64(), IsBigEndian));
+        // HACK: regular ``BytesSwapper.SwapIf(_reader.ReadDouble(), IsBigEndian);`` is probably also not deterministic across .NET 8 and Unity 2022.3.30f1 (LTS)
 
         #endregion
 

diff --git a/ByteSerialization/IO/EndianBinaryWriter.cs b/ByteSerialization/IO/EndianBinaryWriter.cs
@@ -108,10 +108,12 @@ public void Write(ulong value) =>
             _writer.Write(BytesSwapper.SwapIf(value, IsBigEndian));
 
         public void Write(float value) =>
-            _writer.Write(BytesSwapper.SwapIf(value, IsBigEndian));
+            _writer.Write(BytesSwapper.SwapIf(BitConverter.SingleToInt32Bits(value), IsBigEndian));
+        // HACK: regular ``_writer.Write(BytesSwapper.SwapIf(value, IsBigEndian));`` is probably not deterministic across .NET 8 and Unity 2022.3.30f1 (LTS)
 
         public void Write(double value) =>
-            _writer.Write(BytesSwapper.SwapIf(value, IsBigEndian));
+            _writer.Write(BytesSwapper.SwapIf(BitConverter.DoubleToInt64Bits(value), IsBigEndian));
+        // HACK: regular ``_writer.Write(BytesSwapper.SwapIf(value, IsBigEndian));`` is probably not deterministic across .NET 8 and Unity 2022.3.30f1 (LTS)
 
         #endregion