view libtommath/bn_mp_lcm.c @ 350:01e4180895ba

merge of '9a4e042fd565f46141e81e0c1ab90260303348fe' and 'bea3887a5875cf3ab8a1331e15e698b37b61fe37'
author Matt Johnston Mon, 07 Aug 2006 13:41:23 +0000 eed26cff980b 5ff8218bcee9
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```#include <tommath.h>
#ifdef BN_MP_LCM_C
/* LibTomMath, multiple-precision integer library -- Tom St Denis
*
* LibTomMath is a library that provides multiple-precision
* integer arithmetic as well as number theoretic functionality.
*
* The library was designed directly after the MPI library by
* Michael Fromberger but has been written from scratch with
* additional optimizations in place.
*
* The library is free for all purposes without any express
* guarantee it works.
*
* Tom St Denis, [email protected], http://math.libtomcrypt.org
*/

/* computes least common multiple as |a*b|/(a, b) */
int mp_lcm (mp_int * a, mp_int * b, mp_int * c)
{
int     res;
mp_int  t1, t2;

if ((res = mp_init_multi (&t1, &t2, NULL)) != MP_OKAY) {
return res;
}

/* t1 = get the GCD of the two inputs */
if ((res = mp_gcd (a, b, &t1)) != MP_OKAY) {
goto LBL_T;
}

/* divide the smallest by the GCD */
if (mp_cmp_mag(a, b) == MP_LT) {
/* store quotient in t2 such that t2 * b is the LCM */
if ((res = mp_div(a, &t1, &t2, NULL)) != MP_OKAY) {
goto LBL_T;
}
res = mp_mul(b, &t2, c);
} else {
/* store quotient in t2 such that t2 * a is the LCM */
if ((res = mp_div(b, &t1, &t2, NULL)) != MP_OKAY) {
goto LBL_T;
}
res = mp_mul(a, &t2, c);
}

/* fix the sign to positive */
c->sign = MP_ZPOS;

LBL_T:
mp_clear_multi (&t1, &t2, NULL);
return res;
}
#endif
```