/src/dropbear/libtommath/bn_mp_lcm.c
Line | Count | Source (jump to first uncovered line) |
1 | | #include "tommath_private.h" |
2 | | #ifdef BN_MP_LCM_C |
3 | | /* LibTomMath, multiple-precision integer library -- Tom St Denis */ |
4 | | /* SPDX-License-Identifier: Unlicense */ |
5 | | |
6 | | /* computes least common multiple as |a*b|/(a, b) */ |
7 | | mp_err mp_lcm(const mp_int *a, const mp_int *b, mp_int *c) |
8 | 0 | { |
9 | 0 | mp_err err; |
10 | 0 | mp_int t1, t2; |
11 | | |
12 | |
|
13 | 0 | if ((err = mp_init_multi(&t1, &t2, NULL)) != MP_OKAY) { |
14 | 0 | return err; |
15 | 0 | } |
16 | | |
17 | | /* t1 = get the GCD of the two inputs */ |
18 | 0 | if ((err = mp_gcd(a, b, &t1)) != MP_OKAY) { |
19 | 0 | goto LBL_T; |
20 | 0 | } |
21 | | |
22 | | /* divide the smallest by the GCD */ |
23 | 0 | if (mp_cmp_mag(a, b) == MP_LT) { |
24 | | /* store quotient in t2 such that t2 * b is the LCM */ |
25 | 0 | if ((err = mp_div(a, &t1, &t2, NULL)) != MP_OKAY) { |
26 | 0 | goto LBL_T; |
27 | 0 | } |
28 | 0 | err = mp_mul(b, &t2, c); |
29 | 0 | } else { |
30 | | /* store quotient in t2 such that t2 * a is the LCM */ |
31 | 0 | if ((err = mp_div(b, &t1, &t2, NULL)) != MP_OKAY) { |
32 | 0 | goto LBL_T; |
33 | 0 | } |
34 | 0 | err = mp_mul(a, &t2, c); |
35 | 0 | } |
36 | | |
37 | | /* fix the sign to positive */ |
38 | 0 | c->sign = MP_ZPOS; |
39 | |
|
40 | 0 | LBL_T: |
41 | 0 | mp_clear_multi(&t1, &t2, NULL); |
42 | 0 | return err; |
43 | 0 | } |
44 | | #endif |