Mercurial > dropbear
diff src/encauth/ocb/ocb_ntz.c @ 191:1c15b283127b libtomcrypt-orig
Import of libtomcrypt 1.02 with manual path rename rearrangement etc
author | Matt Johnston <matt@ucc.asn.au> |
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date | Fri, 06 May 2005 13:23:02 +0000 |
parents | |
children | 39d5d58461d6 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/encauth/ocb/ocb_ntz.c Fri May 06 13:23:02 2005 +0000 @@ -0,0 +1,38 @@ +/* LibTomCrypt, modular cryptographic library -- Tom St Denis + * + * LibTomCrypt is a library that provides various cryptographic + * algorithms in a highly modular and flexible manner. + * + * The library is free for all purposes without any express + * guarantee it works. + * + * Tom St Denis, [email protected], http://libtomcrypt.org + */ + +/** + @file ocb_ntz.c + OCB implementation, internal function, by Tom St Denis +*/ + +#include "tomcrypt.h" + +#ifdef OCB_MODE + +/** + Returns the number of leading zero bits [from lsb up] + @param x The 32-bit value to observe + @return The number of bits [from the lsb up] that are zero +*/ +int ocb_ntz(unsigned long x) +{ + int c; + x &= 0xFFFFFFFFUL; + c = 0; + while ((x & 1) == 0) { + ++c; + x >>= 1; + } + return c; +} + +#endif