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comparison bn_mp_lcm.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 /* computes least common multiple as |a*b|/(a, b) */
18 int mp_lcm (mp_int * a, mp_int * b, mp_int * c)
19 {
20 int res;
21 mp_int t1, t2;
22
23
24 if ((res = mp_init_multi (&t1, &t2, NULL)) != MP_OKAY) {
25 return res;
26 }
27
28 /* t1 = get the GCD of the two inputs */
29 if ((res = mp_gcd (a, b, &t1)) != MP_OKAY) {
30 goto __T;
31 }
32
33 /* divide the smallest by the GCD */
34 if (mp_cmp_mag(a, b) == MP_LT) {
35 /* store quotient in t2 such that t2 * b is the LCM */
36 if ((res = mp_div(a, &t1, &t2, NULL)) != MP_OKAY) {
37 goto __T;
38 }
39 res = mp_mul(b, &t2, c);
40 } else {
41 /* store quotient in t2 such that t2 * a is the LCM */
42 if ((res = mp_div(b, &t1, &t2, NULL)) != MP_OKAY) {
43 goto __T;
44 }
45 res = mp_mul(a, &t2, c);
46 }
47
48 /* fix the sign to positive */
49 c->sign = MP_ZPOS;
50
51 __T:
52 mp_clear_multi (&t1, &t2, NULL);
53 return res;
54 }