62 lines
1.9 KiB
C#
62 lines
1.9 KiB
C#
using System.Runtime.CompilerServices;
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namespace VersionedSerialization;
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public static class ReaderExtensions
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{
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[MethodImpl(MethodImplOptions.AggressiveInlining)]
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public static uint ReadCompressedUInt<T>(this ref T reader) where T : struct, IReader, allows ref struct
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{
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var first = reader.Read<byte>();
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if ((first & 0b10000000) == 0b00000000)
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return first;
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if ((first & 0b11000000) == 0b10000000)
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return (uint)(((first & ~0b10000000) << 8) | reader.Read<byte>());
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if ((first & 0b11100000) == 0b11000000)
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return (uint)(((first & ~0b11000000) << 24) | (reader.Read<byte>() << 16) | (reader.Read<byte>() << 8) | reader.Read<byte>());
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return first switch
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{
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0b11110000 => reader.Read<uint>(),
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0b11111110 => uint.MaxValue - 1,
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0b11111111 => uint.MaxValue,
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_ => throw new InvalidDataException("Invalid compressed uint")
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};
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}
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[MethodImpl(MethodImplOptions.AggressiveInlining)]
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public static int ReadCompressedInt<T>(this ref T reader) where T : struct, IReader, allows ref struct
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{
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var value = reader.ReadCompressedUInt();
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if (value == uint.MaxValue)
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return int.MinValue;
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var isNegative = (value & 0b1) == 1;
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value >>= 1;
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return (int)(isNegative ? -(value + 1) : value);
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}
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[MethodImpl(MethodImplOptions.AggressiveInlining)]
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public static ulong ReadSLEB128<T>(this ref T reader) where T : struct, IReader, allows ref struct
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{
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var value = 0uL;
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var shift = 0;
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byte current;
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do
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{
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current = reader.Read<byte>();
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value |= (current & 0x7FuL) << shift;
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shift += 7;
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} while ((current & 0x80) != 0);
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if (64 >= shift && (current & 0x40) != 0)
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value |= ulong.MaxValue << shift;
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return value;
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}
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} |