diff options
Diffstat (limited to 'crypto/src/util/Longs.cs')
| -rw-r--r-- | crypto/src/util/Longs.cs | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/crypto/src/util/Longs.cs b/crypto/src/util/Longs.cs index 91dee2b50..66b14b95c 100644 --- a/crypto/src/util/Longs.cs +++ b/crypto/src/util/Longs.cs @@ -9,6 +9,30 @@ namespace Org.BouncyCastle.Utilities public const int NumBits = 64; public const int NumBytes = 8; + private static readonly byte[] DeBruijnTZ = { + 0x3F, 0x00, 0x01, 0x34, 0x02, 0x06, 0x35, 0x1A, 0x03, 0x25, 0x28, 0x07, 0x21, 0x36, 0x2F, 0x1B, + 0x3D, 0x04, 0x26, 0x2D, 0x2B, 0x29, 0x15, 0x08, 0x17, 0x22, 0x3A, 0x37, 0x30, 0x11, 0x1C, 0x0A, + 0x3E, 0x33, 0x05, 0x19, 0x24, 0x27, 0x20, 0x2E, 0x3C, 0x2C, 0x2A, 0x14, 0x16, 0x39, 0x10, 0x09, + 0x32, 0x18, 0x23, 0x1F, 0x3B, 0x13, 0x38, 0x0F, 0x31, 0x1E, 0x12, 0x0E, 0x1D, 0x0D, 0x0C, 0x0B }; + + public static int NumberOfLeadingZeros(long i) + { + int x = (int)(i >> 32), n = 0; + if (x == 0) + { + n = 32; + x = (int)i; + } + return n + Integers.NumberOfLeadingZeros(x); + } + + public static int NumberOfTrailingZeros(long i) + { + int n = DeBruijnTZ[(uint)((ulong)((i & -i) * 0x045FBAC7992A70DAL) >> 58)]; + long m = (((i & 0xFFFFFFFFL) | (long)((ulong)i >> 32)) - 1L) >> 63; + return n - (int)m; + } + public static long Reverse(long i) { i = (long)Bits.BitPermuteStepSimple((ulong)i, 0x5555555555555555UL, 1); |