1 files changed, 12 insertions, 0 deletions
diff --git a/crypto/src/math/raw/Interleave.cs b/crypto/src/math/raw/Interleave.cs
index a45ee1e08..d21840644 100644
--- a/crypto/src/math/raw/Interleave.cs
+++ b/crypto/src/math/raw/Interleave.cs
@@ -91,5 +91,17 @@ namespace Org.BouncyCastle.Math.Raw
z[zOff ] = (x ) & M64;
z[zOff + 1] = (x >> 1) & M64;
}
+
+ internal static ulong Unshuffle(ulong x)
+ {
+ // "unshuffle" even bits to low half and odd bits to high half
+ ulong t;
+ t = (x ^ (x >> 1)) & 0x2222222222222222UL; x ^= (t ^ (t << 1));
+ t = (x ^ (x >> 2)) & 0x0C0C0C0C0C0C0C0CUL; x ^= (t ^ (t << 2));
+ t = (x ^ (x >> 4)) & 0x00F000F000F000F0UL; x ^= (t ^ (t << 4));
+ t = (x ^ (x >> 8)) & 0x0000FF000000FF00UL; x ^= (t ^ (t << 8));
+ t = (x ^ (x >> 16)) & 0x00000000FFFF0000UL; x ^= (t ^ (t << 16));
+ return x;
+ }
}
}
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