denyhosts/clamav/libclamav/tomsfastmath/bit/fp_count_bits.c

37 lines
677 B
C

/* TomsFastMath, a fast ISO C bignum library.
*
* This project is meant to fill in where LibTomMath
* falls short. That is speed ;-)
*
* This project is public domain and free for all purposes.
*
* Tom St Denis, tomstdenis@gmail.com
*/
#include <tfm_private.h>
int fp_count_bits (fp_int * a)
{
int r;
fp_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 > ((fp_digit) 0)) {
++r;
q >>= ((fp_digit) 1);
}
return r;
}
/* $Source$ */
/* $Revision$ */
/* $Date$ */