Donatien Garnier / MiniTLS-GPL

A super trimmed down TLS stack, GPL licensed

Dependents:   MiniTLS-HTTPS-Example

MiniTLS - A super trimmed down TLS/SSL Library for embedded devices Author: Donatien Garnier Copyright (C) 2013-2014 AppNearMe Ltd

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.

math/bit/fp_cnt_lsb.c@4:cbaf466d717d, 2014-06-10 (annotated)

Committer:
MiniTLS
Date:
Tue Jun 10 14:23:09 2014 +0000
Revision:
4:cbaf466d717d
Parent:
0:35aa5be3b78d 
Fixes for mbed

Who changed what in which revision?

UserRevisionLine numberNew contents of line
MiniTLS 0:35aa5be3b78d 1 /* TomsFastMath, a fast ISO C bignum library.
MiniTLS 0:35aa5be3b78d 2 *
MiniTLS 0:35aa5be3b78d 3 * This project is meant to fill in where LibTomMath
MiniTLS 0:35aa5be3b78d 4 * falls short. That is speed ;-)
MiniTLS 0:35aa5be3b78d 5 *
MiniTLS 0:35aa5be3b78d 6 * This project is public domain and free for all purposes.
MiniTLS 0:35aa5be3b78d 7 *
MiniTLS 0:35aa5be3b78d 8 * Tom St Denis, tomstdenis@gmail.com
MiniTLS 0:35aa5be3b78d 9 */
MiniTLS 0:35aa5be3b78d 10 #include <tfm.h>
MiniTLS 0:35aa5be3b78d 11
MiniTLS 0:35aa5be3b78d 12 static const int lnz[16] = {
MiniTLS 0:35aa5be3b78d 13 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0
MiniTLS 0:35aa5be3b78d 14 };
MiniTLS 0:35aa5be3b78d 15
MiniTLS 0:35aa5be3b78d 16 /* Counts the number of lsbs which are zero before the first zero bit */
MiniTLS 0:35aa5be3b78d 17 int fp_cnt_lsb(fp_int *a)
MiniTLS 0:35aa5be3b78d 18 {
MiniTLS 0:35aa5be3b78d 19 int x;
MiniTLS 0:35aa5be3b78d 20 fp_digit q, qq;
MiniTLS 0:35aa5be3b78d 21
MiniTLS 0:35aa5be3b78d 22 /* easy out */
MiniTLS 0:35aa5be3b78d 23 if (fp_iszero(a) == 1) {
MiniTLS 0:35aa5be3b78d 24 return 0;
MiniTLS 0:35aa5be3b78d 25 }
MiniTLS 0:35aa5be3b78d 26
MiniTLS 0:35aa5be3b78d 27 /* scan lower digits until non-zero */
MiniTLS 0:35aa5be3b78d 28 for (x = 0; x < a->used && a->dp[x] == 0; x++);
MiniTLS 0:35aa5be3b78d 29 q = a->dp[x];
MiniTLS 0:35aa5be3b78d 30 x *= DIGIT_BIT;
MiniTLS 0:35aa5be3b78d 31
MiniTLS 0:35aa5be3b78d 32 /* now scan this digit until a 1 is found */
MiniTLS 0:35aa5be3b78d 33 if ((q & 1) == 0) {
MiniTLS 0:35aa5be3b78d 34 do {
MiniTLS 0:35aa5be3b78d 35 qq = q & 15;
MiniTLS 0:35aa5be3b78d 36 x += lnz[qq];
MiniTLS 0:35aa5be3b78d 37 q >>= 4;
MiniTLS 0:35aa5be3b78d 38 } while (qq == 0);
MiniTLS 0:35aa5be3b78d 39 }
MiniTLS 0:35aa5be3b78d 40 return x;
MiniTLS 0:35aa5be3b78d 41 }
MiniTLS 0:35aa5be3b78d 42
MiniTLS 0:35aa5be3b78d 43
MiniTLS 0:35aa5be3b78d 44 /* $Source: /cvs/libtom/tomsfastmath/src/bit/fp_cnt_lsb.c,v $ */
MiniTLS 0:35aa5be3b78d 45 /* $Revision: 1.1 $ */
MiniTLS 0:35aa5be3b78d 46 /* $Date: 2006/12/31 21:25:53 $ */