1 /* $NetBSD: bn_mp_get_int.c,v 1.2 2017/01/28 21:31:47 christos Exp $ */
2
3 #include <tommath.h>
4 #ifdef BN_MP_GET_INT_C
5 /* LibTomMath, multiple-precision integer library -- Tom St Denis
6 *
7 * LibTomMath is a library that provides multiple-precision
8 * integer arithmetic as well as number theoretic functionality.
9 *
10 * The library was designed directly after the MPI library by
11 * Michael Fromberger but has been written from scratch with
12 * additional optimizations in place.
13 *
14 * The library is free for all purposes without any express
15 * guarantee it works.
16 *
17 * Tom St Denis, tomstdenis@gmail.com, http://libtom.org
18 */
19
20 /* get the lower 32-bits of an mp_int */
mp_get_int(mp_int * a)21 unsigned long mp_get_int(mp_int * a)
22 {
23 int i;
24 unsigned long res;
25
26 if (a->used == 0) {
27 return 0;
28 }
29
30 /* get number of digits of the lsb we have to read */
31 i = MIN(a->used,(int)((sizeof(unsigned long)*CHAR_BIT+DIGIT_BIT-1)/DIGIT_BIT))-1;
32
33 /* get most significant digit of result */
34 res = DIGIT(a,i);
35
36 while (--i >= 0) {
37 res = (res << DIGIT_BIT) | DIGIT(a,i);
38 }
39
40 /* force result to 32-bits always so it is consistent on non 32-bit platforms */
41 return res & 0xFFFFFFFFUL;
42 }
43 #endif
44
45 /* Source: /cvs/libtom/libtommath/bn_mp_get_int.c,v */
46 /* Revision: 1.4 */
47 /* Date: 2006/12/28 01:25:13 */
48