view libtommath/bn_mp_count_bits.c @ 1695:93e738ef0d9d

Avoid oss-fuzz $SANITIZER causing wrong build https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=22608
author Matt Johnston <matt@ucc.asn.au>
date Wed, 27 May 2020 20:33:45 +0800
parents 1051e4eea25a
children
line wrap: on
line source

#include "tommath_private.h"
#ifdef BN_MP_COUNT_BITS_C
/* LibTomMath, multiple-precision integer library -- Tom St Denis */
/* SPDX-License-Identifier: Unlicense */

/* returns the number of bits in an int */
int mp_count_bits(const mp_int *a)
{
   int     r;
   mp_digit q;

   /* shortcut */
   if (MP_IS_ZERO(a)) {
      return 0;
   }

   /* get number of digits and add that */
   r = (a->used - 1) * MP_DIGIT_BIT;

   /* take the last digit and count the bits in it */
   q = a->dp[a->used - 1];
   while (q > 0u) {
      ++r;
      q >>= 1u;
   }
   return r;
}
#endif