fix(cs/serialization): Improve precision in date serialization

.env

@@ -1,4 +1,4 @@
-VERSION="3.0.12"
+VERSION="3.0.13"
 MAJOR=3
 MINOR=0
-PATCH=12
+PATCH=13

.github/workflows/integration-tests.yml

@@ -18,6 +18,8 @@ jobs:
         uses: actions/setup-dotnet@v3
         with:
           dotnet-version: 9.0.x
+          dotnet-quality: 'preview'
+
       - name: Setup Rust
         uses: actions-rs/toolchain@v1
         with:

Laboratory/C#/Test/UnitTest1.cs

@@ -22,8 +22,8 @@ public void Setup()
         [Test]
         public void WriteRead()
         {
-            var testBytes = new byte[] {0x1, 0x2, 0x3};
-            var testFloats = new float[] {float.MinValue, float.MaxValue};
+            var testBytes = new byte[] { 0x1, 0x2, 0x3 };
+            var testFloats = new float[] { float.MinValue, float.MaxValue };
             var testDoubles = new double[] { double.MinValue, double.MaxValue };
             var testGuid = Guid.Parse("81c6987b-48b7-495f-ad01-ec20cc5f5be1");
             const string testString = @"Hello 明 World!😊";
@@ -65,7 +65,7 @@ public void WriteRead()
             // test float / double
             Assert.AreEqual(float.MaxValue, output.ReadFloat32());
             Assert.AreEqual(double.MaxValue, output.ReadFloat64());
-             // test float array
+            // test float array
             var floatArrayLength = output.ReadUInt32();
             Assert.AreEqual(testFloats.Length, floatArrayLength);
             var parsedFloats = new float[floatArrayLength];
@@ -88,7 +88,10 @@ public void WriteRead()
             // test guid
             Assert.AreEqual(testGuid, output.ReadGuid());
             // test date
-            Assert.AreEqual(testDate, output.ReadDate());
+            var readDate = output.ReadDate();
+            Console.WriteLine($"Read date: {readDate:O}");
+            Assert.That(readDate, Is.EqualTo(testDate).Within(TimeSpan.FromMilliseconds(1)),
+                $"Dates should match within 1ms. Difference: {(readDate - testDate).TotalMilliseconds}ms");
             // test byte array
             CollectionAssert.AreEqual(testBytes, output.ReadBytes());
 
@@ -109,7 +112,7 @@ public void RoundTrip()
                     new Musician {Name = "Miles Davis", Plays = Instrument.Trumpet}
                 }
             };
-            var library = new Library {Songs = new Dictionary<Guid, Song> {{testGuid, song}}};
+            var library = new Library { Songs = new Dictionary<Guid, Song> { { testGuid, song } } };
             var decodedLibrary = Library.Decode(library.EncodeImmutably());
             Assert.AreEqual(library, decodedLibrary);
         }

Runtime/C#/Runtime/BebopWriter.cs

@@ -13,6 +13,9 @@ namespace Bebop.Runtime
     /// </summary>
     public ref struct BebopWriter
     {
+        const long TicksBetweenEpochs = 621355968000000000L;
+        const long DateMask = 0x3fffffffffffffffL;
+
         // ReSharper disable once InconsistentNaming
         private static readonly UTF8Encoding UTF8 = new();
 
@@ -287,7 +290,9 @@ public void WriteFloat64(double value)
         [MethodImpl(BebopConstants.HotPath)]
         public void WriteDate(DateTime date)
         {
-            WriteInt64(date.ToUniversalTime().ToBinary());
+            long ms = (long)(date.ToUniversalTime() - new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc)).TotalMilliseconds;
+            long ticks = ms * 10000L + TicksBetweenEpochs;
+            WriteInt64(ticks & DateMask);
         }
 
         /// <summary>
@@ -321,7 +326,7 @@ public void WriteString(string value)
                 fixed (char* c = value)
                 {
                     var size = UTF8.GetByteCount(c, value.Length);
-                    WriteUInt32(unchecked((uint) size));
+                    WriteUInt32(unchecked((uint)size));
                     var index = Length;
                     GrowBy(size);
                     fixed (byte* o = _buffer.Slice(index, size))
@@ -365,7 +370,7 @@ public void FillRecordLength(int position, uint messageLength)
         [MethodImpl(BebopConstants.HotPath)]
         public void WriteFloat32S(float[] value)
         {
-            WriteUInt32(unchecked((uint) value.Length));
+            WriteUInt32(unchecked((uint)value.Length));
             var index = Length;
             var floatBytes = AsBytes<float>(value);
             if (floatBytes.IsEmpty)
@@ -382,7 +387,7 @@ public void WriteFloat32S(float[] value)
         [MethodImpl(BebopConstants.HotPath)]
         public void WriteFloat64S(double[] value)
         {
-            WriteUInt32(unchecked((uint) value.Length));
+            WriteUInt32(unchecked((uint)value.Length));
             var index = Length;
             var doubleBytes = AsBytes<double>(value);
             if (doubleBytes.IsEmpty)
@@ -417,7 +422,7 @@ public void WriteBytes(ImmutableArray<byte> value)
         [MethodImpl(BebopConstants.HotPath)]
         public void WriteBytes(byte[] value)
         {
-            WriteUInt32(unchecked((uint) value.Length));
+            WriteUInt32(unchecked((uint)value.Length));
             if (value.Length == 0)
             {
                 return;