File: bn_mp_count_bits.c

package info (click to toggle)
tcl8.6 8.6.17%2Bdfsg-1
  • links: PTS, VCS
  • area: main
  • in suites: forky, sid
  • size: 34,788 kB
  • sloc: ansic: 190,439; tcl: 20,102; makefile: 2,924; sh: 2,623; ada: 1,681; pascal: 1,139; cpp: 1,001; yacc: 904; cs: 879; asm: 468; xml: 95
file content (28 lines) | stat: -rw-r--r-- 576 bytes parent folder | download | duplicates (19)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
#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