The document discusses various methods for efficiently serializing and deserializing data in C# using MessagePack, including: - Methods for reading primitive data types like integers and floats from bytes - Representing float values as individual bytes for efficient serialization - Using lookup tables and decoder interfaces to quickly determine MessagePack types and decode values - Discussing faster alternatives like using direct memory copying instead of serialization delegates - Mentioning how to extend MessagePack specifications while maintaining compatibility for faster serialization

2. https://github.com/neuecc/Messag
ePack-CSharp/

3. Int32 Read(byte[] bytes, int offset)
{
return (bytes[offset + 0] << 24)
| (bytes[offset + 1] << 16)
| (bytes[offset + 2] << 8)
| (bytes[offset + 3]);
}
Int32 Read(byte[] bytes, int offset)
{
return (bytes[offset + 0])
| (bytes[offset + 1] << 8)
| (bytes[offset + 2] << 16)
| (bytes[offset + 3] << 24);
}
unsafe int ReadInt32(byte[] bytes, int
offset)
{
fixed (byte* ptr = bytes)
{
return *(int*)(ptr + offset);
}
}

4. [StructLayout(LayoutKind.Explicit)]
internal struct Float32Bits
{
[FieldOffset(0)]
public float Value;
[FieldOffset(0)]
public Byte Byte0;
[FieldOffset(1)]
public Byte Byte1;
[FieldOffset(2)]
public Byte Byte2;
[FieldOffset(3)]
public Byte Byte3;
}

5. https://github.com/msgpack/msgpack/blob/master/spec.md

6. public MessagepackType ReadMessagePackType(byte[] bytes, int offset)
{
var code = bytes[offset];
if (0 <= code && code <= MessagePackRange.MaxFixPositiveInt)
{
return FixInt;
}
if (MessagePackRange.MinFixNegativeInt <= code)
{
return NegativeInt;
}
switch (code)
{
case Int8:
return Int8;
case Int16:
return Int16;
case Int32:
return Int32;
// 以下略
}

7. static readonly MessagePackType[] typeLookupTable = new MessagePackType[256];
static MessagePackCode()
{
for (int i = MinFixInt; i <= MaxFixInt; i++)
{
typeLookupTable[i] = MessagePackType.Integer;
}
for (int i = MinFixMap; i <= MaxFixMap; i++)
{
typeLookupTable[i] = MessagePackType.Map;
}
typeLookupTable[Nil] = MessagePackType.Nil;
typeLookupTable[False] = MessagePackType.Boolean;
typeLookupTable[True] = MessagePackType.Boolean;
typeLookupTable[Bin8] = MessagePackType.Binary;
typeLookupTable[Bin16] = MessagePackType.Binary;
// 以下略....
}

8. static readonly IMapHeaderDecoder[] mapHeaderDecoders = new IMapHeaderDecoder[MaxSize];
static readonly IArrayHeaderDecoder[] arrayHeaderDecoders = new IArrayHeaderDecoder[MaxSize];
static readonly IBooleanDecoder[] booleanDecoders = new IBooleanDecoder[MaxSize];
static readonly IByteDecoder[] byteDecoders = new IByteDecoder[MaxSize];
static readonly IBytesDecoder[] bytesDecoders = new IBytesDecoder[MaxSize];
static readonly ISByteDecoder[] sbyteDecoders = new ISByteDecoder[MaxSize];
static readonly ISingleDecoder[] singleDecoders = new ISingleDecoder[MaxSize];
static readonly IDoubleDecoder[] doubleDecoders = new IDoubleDecoder[MaxSize];
static readonly IInt16Decoder[] int16Decoders = new IInt16Decoder[MaxSize];
static readonly IInt32Decoder[] int32Decoders = new IInt32Decoder[MaxSize];
static readonly IInt64Decoder[] int64Decoders = new IInt64Decoder[MaxSize];
static readonly IUInt16Decoder[] uint16Decoders = new IUInt16Decoder[MaxSize];
static readonly IUInt32Decoder[] uint32Decoders = new IUInt32Decoder[MaxSize];
static readonly IUInt64Decoder[] uint64Decoders = new IUInt64Decoder[MaxSize];
static readonly IStringDecoder[] stringDecoders = new IStringDecoder[MaxSize];
static readonly IExtDecoder[] extDecoders = new IExtDecoder[MaxSize];
static readonly IExtHeaderDecoder[] extHeaderDecoders = new IExtHeaderDecoder[MaxSize];
static readonly IDateTimeDecoder[] dateTimeDecoders = new IDateTimeDecoder[MaxSize];
static readonly IReadNextDecoder[] readNextDecoders = new IReadNextDecoder[MaxSize];

9. static readonly IMapHeaderDecoder[] mapHeaderDecoders = new IMapHeaderDecoder[MaxSize];
static readonly IArrayHeaderDecoder[] arrayHeaderDecoders = new IArrayHeaderDecoder[MaxSize];
static readonly IBooleanDecoder[] booleanDecoders = new IBooleanDecoder[MaxSize];
static readonly IByteDecoder[] byteDecoders = new IByteDecoder[MaxSize];
static readonly IBytesDecoder[] bytesDecoders = new IBytesDecoder[MaxSize];
static readonly ISByteDecoder[] sbyteDecoders = new ISByteDecoder[MaxSize];
static readonly ISingleDecoder[] singleDecoders = new ISingleDecoder[MaxSize];
static readonly IDoubleDecoder[] doubleDecoders = new IDoubleDecoder[MaxSize];
static readonly IInt16Decoder[] int16Decoders = new IInt16Decoder[MaxSize];
static readonly IInt32Decoder[] int32Decoders = new IInt32Decoder[MaxSize];
static readonly IInt64Decoder[] int64Decoders = new IInt64Decoder[MaxSize];
static readonly IUInt16Decoder[] uint16Decoders = new IUInt16Decoder[MaxSize];
static readonly IUInt32Decoder[] uint32Decoders = new IUInt32Decoder[MaxSize];
static readonly IUInt64Decoder[] uint64Decoders = new IUInt64Decoder[MaxSize];
static readonly IStringDecoder[] stringDecoders = new IStringDecoder[MaxSize];
static readonly IExtDecoder[] extDecoders = new IExtDecoder[MaxSize];
static readonly IExtHeaderDecoder[] extHeaderDecoders = new IExtHeaderDecoder[MaxSize];
static readonly IDateTimeDecoder[] dateTimeDecoders = new IDateTimeDecoder[MaxSize];
static readonly IReadNextDecoder[] readNextDecoders = new IReadNextDecoder[MaxSize];
internal interface IInt32Decoder
{
Int32 Read(byte[] bytes, int offset, out int readSize);
}

10. デリゲートは楽
が、Fastestではない

11. void BlockCopy(Array src, int srcOffset, Array dst, int dstOffset, int count)

12. byte[] WriteVector3(Vector3[] collection)
{
var bytes = new byte[collection.Length * 12];
foreach (var item in collection)
{
WriteFloat(bytes, item.x);
WriteFloat(bytes, item.y);
WriteFloat(bytes, item.z);
}
return bytes;
}

14. public static unsafe void SimpleMemoryCopy(void* dest, void* src, int byteCount)
{
var pDest = (byte*)dest;
var pSrc = (byte*)src;
for (int i = 0; i < byteCount; i++)
{
*pDest = *pSrc;
pDest++;
pSrc++;
}
}

15. Vector3[]を一応Unityネイティブの
JsonUtilityの50倍高速にコピー可能
MessagePackの仕様内を逸脱しないよ
うに、Extension Formatを先頭識別子
に埋め込むことで互換性を保ちつつ
高速化