From 3a926f0228c68d7d91cf3946624d7859976440ec Mon Sep 17 00:00:00 2001 From: Ladislav Zezula Date: Fri, 11 Jan 2013 14:55:08 +0100 Subject: Initial creation --- src/libtommath/bn_mp_count_bits.c | 45 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+) create mode 100644 src/libtommath/bn_mp_count_bits.c (limited to 'src/libtommath/bn_mp_count_bits.c') diff --git a/src/libtommath/bn_mp_count_bits.c b/src/libtommath/bn_mp_count_bits.c new file mode 100644 index 0000000..9d8640f --- /dev/null +++ b/src/libtommath/bn_mp_count_bits.c @@ -0,0 +1,45 @@ +#include "tommath.h" +#ifdef BN_MP_COUNT_BITS_C +/* LibTomMath, multiple-precision integer library -- Tom St Denis + * + * LibTomMath is a library that provides multiple-precision + * integer arithmetic as well as number theoretic functionality. + * + * The library was designed directly after the MPI library by + * Michael Fromberger but has been written from scratch with + * additional optimizations in place. + * + * The library is free for all purposes without any express + * guarantee it works. + * + * Tom St Denis, tomstdenis@gmail.com, http://libtom.org + */ + +/* returns the number of bits in an int */ +int +mp_count_bits (mp_int * a) +{ + int r; + mp_digit q; + + /* shortcut */ + if (a->used == 0) { + return 0; + } + + /* get number of digits and add that */ + r = (a->used - 1) * DIGIT_BIT; + + /* take the last digit and count the bits in it */ + q = a->dp[a->used - 1]; + while (q > ((mp_digit) 0)) { + ++r; + q >>= ((mp_digit) 1); + } + return r; +} +#endif + +/* $Source: /cvs/libtom/libtommath/bn_mp_count_bits.c,v $ */ +/* $Revision: 1.4 $ */ +/* $Date: 2006/12/28 01:25:13 $ */ -- cgit v1.2.3