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Expose the IBinaryInteger<T>.ReadBig/LittleEndian APIs #73274

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Merged
merged 6 commits into from
Aug 4, 2022
Merged

Expose the IBinaryInteger<T>.ReadBig/LittleEndian APIs #73274

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3eadbcf
Adding the IBinaryInteger<T>.ReadLittleEndian and IBinaryInteger<T>.R…
tannergooding Aug 2, 2022
3eaf1d1
Adding tests for the IBinaryInteger<T>.ReadLittleEndian and IBinaryIn…
tannergooding Aug 2, 2022
f0cd89b
Ensure IBinaryInteger<T>.ReadBig/LittleEndian APIs take ROSpan
tannergooding Aug 3, 2022
05ac035
Update src/libraries/System.Private.CoreLib/src/System/Byte.cs
tannergooding Aug 4, 2022
660c968
Fix accidentally removed 0 in char
tannergooding Aug 4, 2022
d6d269d
Update IndexOfAny to compare against >= 0, rather than != -1
tannergooding Aug 4, 2022
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16 changes: 16 additions & 0 deletions src/libraries/Common/tests/System/GenericMathHelpers.cs
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Expand Up @@ -29,12 +29,28 @@ public static class BinaryIntegerHelper<TSelf>

public static TSelf PopCount(TSelf value) => TSelf.PopCount(value);

public static TSelf ReadBigEndian(byte[] source, bool isUnsigned) => TSelf.ReadBigEndian(source, isUnsigned);

public static TSelf ReadBigEndian(byte[] source, int startIndex, bool isUnsigned) => TSelf.ReadBigEndian(source, startIndex, isUnsigned);

public static TSelf ReadBigEndian(Span<byte> source, bool isUnsigned) => TSelf.ReadBigEndian(source, isUnsigned);

public static TSelf ReadLittleEndian(byte[] source, bool isUnsigned) => TSelf.ReadLittleEndian(source, isUnsigned);

public static TSelf ReadLittleEndian(byte[] source, int startIndex, bool isUnsigned) => TSelf.ReadLittleEndian(source, startIndex, isUnsigned);

public static TSelf ReadLittleEndian(Span<byte> source, bool isUnsigned) => TSelf.ReadLittleEndian(source, isUnsigned);

public static TSelf RotateLeft(TSelf value, int rotateAmount) => TSelf.RotateLeft(value, rotateAmount);

public static TSelf RotateRight(TSelf value, int rotateAmount) => TSelf.RotateRight(value, rotateAmount);

public static TSelf TrailingZeroCount(TSelf value) => TSelf.TrailingZeroCount(value);

public static bool TryReadBigEndian(ReadOnlySpan<byte> source, bool isUnsigned, out TSelf value) => TSelf.TryReadBigEndian(source, isUnsigned, out value);

public static bool TryReadLittleEndian(ReadOnlySpan<byte> source, bool isUnsigned, out TSelf value) => TSelf.TryReadLittleEndian(source, isUnsigned, out value);

public static int GetByteCount(TSelf value) => value.GetByteCount();

public static int GetShortestBitLength(TSelf value) => value.GetShortestBitLength();
Expand Down
52 changes: 52 additions & 0 deletions src/libraries/System.Private.CoreLib/src/System/Buffers/Binary/Reader.cs
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Expand Up @@ -4,6 +4,16 @@
using System.Numerics;
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@stephentoub stephentoub Aug 3, 2022

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Not related to this PR, but we should rename this file at some point.

using System.Runtime.CompilerServices;

#pragma warning disable SA1121 // explicitly using type aliases instead of built-in types

#if TARGET_64BIT
using nint_t = System.Int64;
using nuint_t = System.UInt64;
#else
using nint_t = System.Int32;
using nuint_t = System.UInt32;
#endif

namespace System.Buffers.Binary
{
/// <summary>
Expand Down Expand Up @@ -44,6 +54,24 @@ public static partial class BinaryPrimitives
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static long ReverseEndianness(long value) => (long)ReverseEndianness((ulong)value);

/// <summary>
/// Reverses a signed native-sized integral value - performs an endianness swap
/// </summary>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
internal static nint ReverseEndianness(nint value) => (nint)ReverseEndianness((nint_t)value);

/// <summary>
/// Reverses a signed 128-bit integral value - performs an endianness swap
/// </summary>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
internal static Int128 ReverseEndianness(Int128 value)
{
return new Int128(
ReverseEndianness(value.Lower),
ReverseEndianness(value.Upper)
);
}

/// <summary>
/// This is a no-op and added only for consistency.
/// This allows the caller to read a struct of numeric primitives and reverse each field
Expand All @@ -70,6 +98,12 @@ public static ushort ReverseEndianness(ushort value)
return (ushort)((value >> 8) + (value << 8));
}

/// <summary>
/// Reverses a 16-bit character value - performs an endianness swap
/// </summary>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
internal static char ReverseEndianness(char value) => (char)ReverseEndianness((ushort)value);

/// <summary>
/// Reverses a primitive value - performs an endianness swap
/// </summary>
Expand Down Expand Up @@ -116,5 +150,23 @@ public static ulong ReverseEndianness(ulong value)
return ((ulong)ReverseEndianness((uint)value) << 32)
+ ReverseEndianness((uint)(value >> 32));
}

/// <summary>
/// Reverses an unsigned native-sized integral value - performs an endianness swap
/// </summary>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
internal static nuint ReverseEndianness(nuint value) => (nuint)ReverseEndianness((nuint_t)value);

/// <summary>
/// Reverses an unsigned 128-bit integral value - performs an endianness swap
/// </summary>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
internal static UInt128 ReverseEndianness(UInt128 value)
{
return new UInt128(
ReverseEndianness(value.Lower),
ReverseEndianness(value.Upper)
);
}
}
}
71 changes: 69 additions & 2 deletions src/libraries/System.Private.CoreLib/src/System/Byte.cs
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@@ -1,6 +1,7 @@
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using System.Buffers.Binary;
using System.Diagnostics.CodeAnalysis;
using System.Globalization;
using System.Numerics;
Expand Down Expand Up @@ -332,6 +333,72 @@ object IConvertible.ToType(Type type, IFormatProvider? provider)
/// <inheritdoc cref="IBinaryInteger{TSelf}.TrailingZeroCount(TSelf)" />
public static byte TrailingZeroCount(byte value) => (byte)(BitOperations.TrailingZeroCount(value << 24) - 24);

/// <inheritdoc cref="IBinaryInteger{TSelf}.TryReadBigEndian(ReadOnlySpan{byte}, bool, out TSelf)" />
static bool IBinaryInteger<byte>.TryReadBigEndian(ReadOnlySpan<byte> source, bool isUnsigned, out byte value)
{
byte result = default;

if (source.Length != 0)
{
if (!isUnsigned && sbyte.IsNegative((sbyte)source[0]))
{
// When we are signed and the sign bit is set we are negative and therefore
// definitely out of range

value = result;
return false;
}

if ((source.Length > sizeof(byte)) && (source[..^sizeof(byte)].IndexOfAnyExcept((byte)0x00) >= 0))
{
// When we have any non-zero leading data, we are a large positive and therefore
// definitely out of range

value = result;
return false;
}

// We only have 1-byte so read it directly
result = Unsafe.Add(ref MemoryMarshal.GetReference(source), source.Length - sizeof(byte));
}

value = result;
return true;
}

/// <inheritdoc cref="IBinaryInteger{TSelf}.TryReadLittleEndian(ReadOnlySpan{byte}, bool, out TSelf)" />
static bool IBinaryInteger<byte>.TryReadLittleEndian(ReadOnlySpan<byte> source, bool isUnsigned, out byte value)
{
byte result = default;

if (source.Length != 0)
{
if (!isUnsigned && sbyte.IsNegative((sbyte)source[^1]))
{
// When we are signed and the sign bit is set, we are negative and therefore
// definitely out of range

value = result;
return false;
}

if ((source.Length > sizeof(byte)) && (source[sizeof(byte)..].IndexOfAnyExcept((byte)0x00) >= 0))
{
// When we have any non-zero leading data, we are a large positive and therefore
// definitely out of range

value = result;
return false;
}

// We only have 1-byte so read it directly
result = MemoryMarshal.GetReference(source);
}

value = result;
return true;
}

/// <inheritdoc cref="IBinaryInteger{TSelf}.GetShortestBitLength()" />
int IBinaryInteger<byte>.GetShortestBitLength() => (sizeof(byte) * 8) - LeadingZeroCount(m_value);

Expand All @@ -344,7 +411,7 @@ bool IBinaryInteger<byte>.TryWriteBigEndian(Span<byte> destination, out int byte
if (destination.Length >= sizeof(byte))
{
byte value = m_value;
Unsafe.WriteUnaligned(ref MemoryMarshal.GetReference(destination), value);
MemoryMarshal.GetReference(destination) = value;

bytesWritten = sizeof(byte);
return true;
Expand All @@ -362,7 +429,7 @@ bool IBinaryInteger<byte>.TryWriteLittleEndian(Span<byte> destination, out int b
if (destination.Length >= sizeof(byte))
{
byte value = m_value;
Unsafe.WriteUnaligned(ref MemoryMarshal.GetReference(destination), value);
MemoryMarshal.GetReference(destination) = value;

bytesWritten = sizeof(byte);
return true;
Expand Down
128 changes: 113 additions & 15 deletions src/libraries/System.Private.CoreLib/src/System/Char.cs
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Expand Up @@ -63,21 +63,21 @@ public readonly struct Char
{
// 0 1 2 3 4 5 6 7 8 9 A B C D E F
0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x8E, 0x8E, 0x8E, 0x8E, 0x8E, 0x0E, 0x0E, // U+0000..U+000F
0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, // U+0010..U+001F
0x8B, 0x18, 0x18, 0x18, 0x1A, 0x18, 0x18, 0x18, 0x14, 0x15, 0x18, 0x19, 0x18, 0x13, 0x18, 0x18, // U+0020..U+002F
0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x18, 0x18, 0x19, 0x19, 0x19, 0x18, // U+0030..U+003F
0x18, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, // U+0040..U+004F
0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x14, 0x18, 0x15, 0x1B, 0x12, // U+0050..U+005F
0x1B, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, // U+0060..U+006F
0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x14, 0x19, 0x15, 0x19, 0x0E, // U+0070..U+007F
0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x8E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, // U+0080..U+008F
0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, // U+0090..U+009F
0x8B, 0x18, 0x1A, 0x1A, 0x1A, 0x1A, 0x1C, 0x18, 0x1B, 0x1C, 0x04, 0x16, 0x19, 0x0F, 0x1C, 0x1B, // U+00A0..U+00AF
0x1C, 0x19, 0x0A, 0x0A, 0x1B, 0x21, 0x18, 0x18, 0x1B, 0x0A, 0x04, 0x17, 0x0A, 0x0A, 0x0A, 0x18, // U+00B0..U+00BF
0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, // U+00C0..U+00CF
0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x19, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x21, // U+00D0..U+00DF
0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, // U+00E0..U+00EF
0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x19, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, // U+00F0..U+00FF
0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, // U+0001..U+001F
0x8B, 0x18, 0x18, 0x18, 0x1A, 0x18, 0x18, 0x18, 0x14, 0x15, 0x18, 0x19, 0x18, 0x13, 0x18, 0x18, // U+0002..U+002F
0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x18, 0x18, 0x19, 0x19, 0x19, 0x18, // U+0003..U+003F
0x18, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, // U+0004..U+004F
0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x14, 0x18, 0x15, 0x1B, 0x12, // U+0005..U+005F
0x1B, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, // U+0006..U+006F
0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x14, 0x19, 0x15, 0x19, 0x0E, // U+0007..U+007F
0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x8E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, // U+0008..U+008F
0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, // U+0009..U+009F
0x8B, 0x18, 0x1A, 0x1A, 0x1A, 0x1A, 0x1C, 0x18, 0x1B, 0x1C, 0x04, 0x16, 0x19, 0x0F, 0x1C, 0x1B, // U+000A..U+00AF
0x1C, 0x19, 0x0A, 0x0A, 0x1B, 0x21, 0x18, 0x18, 0x1B, 0x0A, 0x04, 0x17, 0x0A, 0x0A, 0x0A, 0x18, // U+000B..U+00BF
0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, // U+000C..U+00CF
0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x19, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x21, // U+000D..U+00DF
0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, // U+000E..U+00EF
0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x19, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, // U+000F..U+00FF
};

// Return true for all characters below or equal U+00ff, which is ASCII + Latin-1 Supplement.
Expand Down Expand Up @@ -1179,6 +1179,104 @@ public static int ConvertToUtf32(string s, int index)
/// <inheritdoc cref="IBinaryInteger{TSelf}.TrailingZeroCount(TSelf)" />
static char IBinaryInteger<char>.TrailingZeroCount(char value) => (char)(BitOperations.TrailingZeroCount(value << 16) - 16);

/// <inheritdoc cref="IBinaryInteger{TSelf}.TryReadBigEndian(ReadOnlySpan{byte}, bool, out TSelf)" />
static bool IBinaryInteger<char>.TryReadBigEndian(ReadOnlySpan<byte> source, bool isUnsigned, out char value)
{
char result = default;

if (source.Length != 0)
{
if (!isUnsigned && sbyte.IsNegative((sbyte)source[0]))
{
// When we are signed and the sign bit is set, we are negative and therefore
// definitely out of range

value = result;
return false;
}

if ((source.Length > sizeof(char)) && (source[..^sizeof(char)].IndexOfAnyExcept((byte)0x00) >= 0))
{
// When we have any non-zero leading data, we are a large positive and therefore
// definitely out of range

value = result;
return false;
}

ref byte sourceRef = ref MemoryMarshal.GetReference(source);

if (source.Length >= sizeof(char))
{
sourceRef = ref Unsafe.Add(ref sourceRef, source.Length - sizeof(char));

// We have at least 2 bytes, so just read the ones we need directly
result = Unsafe.ReadUnaligned<char>(ref sourceRef);

if (BitConverter.IsLittleEndian)
{
result = BinaryPrimitives.ReverseEndianness(result);
}
}
else
{
// We only have 1-byte so read it directly
result = (char)sourceRef;
}
}

value = result;
return true;
}

/// <inheritdoc cref="IBinaryInteger{TSelf}.TryReadLittleEndian(ReadOnlySpan{byte}, bool, out TSelf)" />
static bool IBinaryInteger<char>.TryReadLittleEndian(ReadOnlySpan<byte> source, bool isUnsigned, out char value)
{
char result = default;

if (source.Length != 0)
{
if (!isUnsigned && sbyte.IsNegative((sbyte)source[^1]))
{
// When we are signed and the sign bit is set, we are negative and therefore
// definitely out of range

value = result;
return false;
}

if ((source.Length > sizeof(char)) && (source[sizeof(char)..].IndexOfAnyExcept((byte)0x00) >= 0))
{
// When we have any non-zero leading data, we are a large positive and therefore
// definitely out of range

value = result;
return false;
}

ref byte sourceRef = ref MemoryMarshal.GetReference(source);

if (source.Length >= sizeof(char))
{
// We have at least 2 bytes, so just read the ones we need directly
result = Unsafe.ReadUnaligned<char>(ref sourceRef);

if (!BitConverter.IsLittleEndian)
{
result = BinaryPrimitives.ReverseEndianness(result);
}
}
else
{
// We only have 1-byte so read it directly
result = (char)sourceRef;
}
}

value = result;
return true;
}

/// <inheritdoc cref="IBinaryInteger{TSelf}.GetShortestBitLength()" />
int IBinaryInteger<char>.GetShortestBitLength() => (sizeof(char) * 8) - ushort.LeadingZeroCount(m_value);

Expand Down
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