1 files changed, 47 insertions, 0 deletions
diff --git a/extra/admin-api/Spacebar.Offload/Extensions/MurmurHash3.cs b/extra/admin-api/Spacebar.Offload/Extensions/MurmurHash3.cs
new file mode 100644
index 000000000..dfa9f3018
--- /dev/null
+++ b/extra/admin-api/Spacebar.Offload/Extensions/MurmurHash3.cs
@@ -0,0 +1,47 @@
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+using static System.Numerics.BitOperations;
+
+namespace Spacebar.Offload.Extensions;
+
+// https://github.com/JeremyEspresso/MurmurHash/blob/master/src/MurmurHash/MurmurHash3.cs
+// Changes: Default seed to 0
+public static class MurmurHash3
+{
+ /// <summary>
+ /// Hashes the <paramref name="bytes"/> into a MurmurHash3 as a <see cref="uint"/>.
+ /// </summary>
+ /// <param name="bytes">The span.</param>
+ /// <param name="seed">The seed for this algorithm.</param>
+ /// <returns>The MurmurHash3 as a <see cref="uint"/></returns>
+ [MethodImpl(MethodImplOptions.AggressiveInlining)]
+ public static uint Hash32(ref ReadOnlySpan<byte> bytes, uint seed = 0)
+ {
+ ref byte bp = ref MemoryMarshal.GetReference(bytes);
+ ref uint endPoint = ref Unsafe.Add(ref Unsafe.As<byte, uint>(ref bp), bytes.Length >> 2);
+ if (bytes.Length >= 4)
+ {
+ do
+ {
+ seed = RotateLeft(seed ^ RotateLeft(Unsafe.ReadUnaligned<uint>(ref bp) * 3432918353U, 15) * 461845907U, 13) * 5 - 430675100;
+ bp = ref Unsafe.Add(ref bp, 4);
+ } while (Unsafe.IsAddressLessThan(ref Unsafe.As<byte, uint>(ref bp), ref endPoint));
+ }
+
+ var remainder = bytes.Length & 3;
+ if (remainder > 0)
+ {
+ uint num = 0;
+ if (remainder > 2) num ^= Unsafe.Add(ref endPoint, 2) << 16;
+ if (remainder > 1) num ^= Unsafe.Add(ref endPoint, 1) << 8;
+ num ^= endPoint;
+
+ seed ^= RotateLeft(num * 3432918353U, 15) * 461845907U;
+ }
+
+ seed ^= (uint)bytes.Length;
+ seed = (uint)((seed ^ (seed >> 16)) * -2048144789);
+ seed = (uint)((seed ^ (seed >> 13)) * -1028477387);
+ return seed ^ seed >> 16;
+ }
+}
\ No newline at end of file
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