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Add BinaryPrimitives.ReverseEndianness for spans of elements #76339

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Merged
adamsitnik merged 9 commits into from
Nov 4, 2022
Merged

Add BinaryPrimitives.ReverseEndianness for spans of elements #76339

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09658e8
Add BinaryPrimitives.ReverseEndianness for spans of elements
stephentoub Sep 28, 2022
aab482d
Merge branch 'main' into reverseendianness
stephentoub Oct 10, 2022
0173cc8
Simplify ReverseEndianness
stephentoub Oct 10, 2022
389ef58
Tweaks for PR feedback
stephentoub Oct 10, 2022
4850d78
Merge branch 'dotnet:main' into reverseendianness
stephentoub Oct 11, 2022
7452594
Merge branch 'dotnet:main' into reverseendianness
stephentoub Oct 12, 2022
08d65ac
Merge branch 'dotnet:main' into reverseendianness
stephentoub Nov 2, 2022
3413d86
Merge branch 'main' into reverseendianness
stephentoub Nov 4, 2022
6fc0d7f
Address PR feedback
stephentoub Nov 4, 2022
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68 changes: 38 additions & 30 deletions ...es/System.Private.CoreLib/src/System/Buffers/Binary/BinaryPrimitives.ReverseEndianness.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -135,7 +135,6 @@ private static void ReverseEndianness<T, TReverser>(ReadOnlySpan<T> source, Span

ref T sourceRef = ref MemoryMarshal.GetReference(source);
ref T destRef = ref MemoryMarshal.GetReference(destination);
ref T end = ref Unsafe.Add(ref sourceRef, source.Length);

if (Unsafe.AreSame(ref sourceRef, ref destRef) ||
!source.Overlaps(destination, out int elementOffset) ||
Expand All @@ -146,36 +145,38 @@ private static void ReverseEndianness<T, TReverser>(ReadOnlySpan<T> source, Span
// to end of the source and not have to worry about writing into the destination and clobbering
// source data we haven't yet read.

if (Vector128.IsHardwareAccelerated && source.Length >= Vector128<T>.Count)
int i = 0;

if (Vector256.IsHardwareAccelerated)
{
if (Vector256.IsHardwareAccelerated && source.Length >= Vector256<T>.Count)
while (i <= source.Length - Vector256<T>.Count)
{
ref T end256 = ref Unsafe.Add(ref sourceRef, source.Length - Vector256<T>.Count + 1);
do
{
Vector256.StoreUnsafe(TReverser.Reverse(Vector256.LoadUnsafe(ref sourceRef)), ref destRef);
sourceRef = ref Unsafe.Add(ref sourceRef, Vector256<T>.Count);
destRef = ref Unsafe.Add(ref destRef, Vector256<T>.Count);
}
while (Unsafe.IsAddressLessThan(ref sourceRef, ref end256));
Vector256.StoreUnsafe(TReverser.Reverse(Vector256.LoadUnsafe(ref sourceRef, (nuint)i)), ref destRef, (nuint)i);
i += Vector256<T>.Count;
}
else

if (Vector128.IsHardwareAccelerated)
{
ref T end128 = ref Unsafe.Add(ref sourceRef, source.Length - (Vector128<T>.Count - 1));
while (Unsafe.IsAddressLessThan(ref sourceRef, ref end128))
if (i <= source.Length - Vector128<T>.Count)
{
Vector128.StoreUnsafe(TReverser.Reverse(Vector128.LoadUnsafe(ref sourceRef)), ref destRef);
sourceRef = ref Unsafe.Add(ref sourceRef, Vector128<T>.Count);
destRef = ref Unsafe.Add(ref destRef, Vector128<T>.Count);
Vector128.StoreUnsafe(TReverser.Reverse(Vector128.LoadUnsafe(ref sourceRef, (nuint)i)), ref destRef, (nuint)i);
i += Vector128<T>.Count;
}
}
}
else if (Vector128.IsHardwareAccelerated)
{
while (i <= source.Length - Vector128<T>.Count)
{
Vector128.StoreUnsafe(TReverser.Reverse(Vector128.LoadUnsafe(ref sourceRef, (nuint)i)), ref destRef, (nuint)i);
i += Vector128<T>.Count;
}
}

while (Unsafe.IsAddressLessThan(ref sourceRef, ref end))
while (i < source.Length)
{
destRef = TReverser.Reverse(sourceRef);
sourceRef = ref Unsafe.Add(ref sourceRef, 1);
destRef = ref Unsafe.Add(ref destRef, 1);
Unsafe.Add(ref destRef, i) = TReverser.Reverse(Unsafe.Add(ref sourceRef, i));
i++;
}
}
else
Expand All @@ -186,29 +187,36 @@ private static void ReverseEndianness<T, TReverser>(ReadOnlySpan<T> source, Span

int i = source.Length;

if (Vector128.IsHardwareAccelerated && source.Length >= Vector128<T>.Count)
if (Vector256.IsHardwareAccelerated)
{
if (Vector256.IsHardwareAccelerated)
while (i >= Vector256<T>.Count)
{
while (i >= Vector256<T>.Count)
i -= Vector256<T>.Count;
Vector256.StoreUnsafe(TReverser.Reverse(Vector256.LoadUnsafe(ref sourceRef, (nuint)i)), ref destRef, (nuint)i);
}

if (Vector128.IsHardwareAccelerated)
{
if (i >= Vector128<T>.Count)
{
i -= Vector256<T>.Count;
Vector256.StoreUnsafe(TReverser.Reverse(Vector256.LoadUnsafe(ref sourceRef, (nuint)i)), ref destRef, (nuint)i);
i -= Vector128<T>.Count;
Vector128.StoreUnsafe(TReverser.Reverse(Vector128.LoadUnsafe(ref sourceRef, (nuint)i)), ref destRef, (nuint)i);
}
}

}
else if (Vector128.IsHardwareAccelerated)
{
while (i >= Vector128<T>.Count)
{
i -= Vector128<T>.Count;
Vector128.StoreUnsafe(TReverser.Reverse(Vector128.LoadUnsafe(ref sourceRef, (nuint)i)), ref destRef, (nuint)i);
}
}

i--;
while (i >= 0)
while (i > 0)
{
Unsafe.Add(ref destRef, i) = TReverser.Reverse(Unsafe.Add(ref sourceRef, i));
i--;
Unsafe.Add(ref destRef, i) = TReverser.Reverse(Unsafe.Add(ref sourceRef, i));
}
}
}
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