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comparison tomsfastmath/src/bit/fp_count_bits.c @ 643:a362b62d38b2 dropbear-tfm

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Add tomsfastmath from git rev bfa4582842bc3bab42e4be4aed5703437049502a with Makefile.in renamed
author Matt Johnston <matt@ucc.asn.au>
date Wed, 23 Nov 2011 18:10:20 +0700
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642:33fd2f3499d2 643:a362b62d38b2
1 /* TomsFastMath, a fast ISO C bignum library.
2 *
3 * This project is meant to fill in where LibTomMath
4 * falls short. That is speed ;-)
5 *
6 * This project is public domain and free for all purposes.
7 *
8 * Tom St Denis, [email protected]
9 */
10 #include <tfm.h>
11
12 int fp_count_bits (fp_int * a)
13 {
14 int r;
15 fp_digit q;
16
17 /* shortcut */
18 if (a->used == 0) {
19 return 0;
20 }
21
22 /* get number of digits and add that */
23 r = (a->used - 1) * DIGIT_BIT;
24
25 /* take the last digit and count the bits in it */
26 q = a->dp[a->used - 1];
27 while (q > ((fp_digit) 0)) {
28 ++r;
29 q >>= ((fp_digit) 1);
30 }
31 return r;
32 }
33
34 /* $Source$ */
35 /* $Revision$ */
36 /* $Date$ */