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comparison bn_mp_get_int.c @ 1:22d5cf7d4b1a libtommath

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Renaming branch
author Matt Johnston <matt@ucc.asn.au>
date Mon, 31 May 2004 18:23:46 +0000
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-1:000000000000 1:22d5cf7d4b1a
1 /* LibTomMath, multiple-precision integer library -- Tom St Denis
2 *
3 * LibTomMath is a library that provides multiple-precision
4 * integer arithmetic as well as number theoretic functionality.
5 *
6 * The library was designed directly after the MPI library by
7 * Michael Fromberger but has been written from scratch with
8 * additional optimizations in place.
9 *
10 * The library is free for all purposes without any express
11 * guarantee it works.
12 *
13 * Tom St Denis, [email protected], http://math.libtomcrypt.org
14 */
15 #include <tommath.h>
16
17 /* get the lower 32-bits of an mp_int */
18 unsigned long mp_get_int(mp_int * a)
19 {
20 int i;
21 unsigned long res;
22
23 if (a->used == 0) {
24 return 0;
25 }
26
27 /* get number of digits of the lsb we have to read */
28 i = MIN(a->used,(int)((sizeof(unsigned long)*CHAR_BIT+DIGIT_BIT-1)/DIGIT_BIT))-1;
29
30 /* get most significant digit of result */
31 res = DIGIT(a,i);
32
33 while (--i >= 0) {
34 res = (res << DIGIT_BIT) | DIGIT(a,i);
35 }
36
37 /* force result to 32-bits always so it is consistent on non 32-bit platforms */
38 return res & 0xFFFFFFFFUL;
39 }