FastXor

by Stan Drapkin

Fast Xor for .NET

SIMD-accelerated XOR operations on byte spans for up to 32x speedup.

• Uses System.Numerics.Tensors.TensorPrimitives.Xor for high-performance platform-optimized vectorized XOR.
• Target: .NET 10+.
• Speedup: Performance depends on runtime and CPU SIMD support.
• Safety: Methods are static, stateless, and safe for concurrent use.
• All spans must have equal length (ArgumentOutOfRangeException is thrown otherwise).

Installation (NuGet):

dotnet add package FastXor

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Methods:

///Xor's left byte span into dest byte span.
public static void Xor(Span<byte> dest, ReadOnlySpan<byte> left)

///Xor's left and right byte spans into dest byte span.
public static void Xor(Span<byte> dest, ReadOnlySpan<byte> left, ReadOnlySpan<byte> right)

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Example:

// using SecurityDriven;

// In-place XOR: dest ^= left (lengths must match)
Span<byte> dest = stackalloc byte[64];
ReadOnlySpan<byte> left = new byte[64];
FastXor.Xor(dest, left);

// Two-source XOR: dest = left ^ right (all lengths must match)
ReadOnlySpan<byte> right = new byte[64];
FastXor.Xor(dest, left, right);