tommath/bn_mp_mod.c

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#include <tommath_private.h>
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#ifdef BN_MP_MOD_C
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/* LibTomMath, multiple-precision integer library -- Tom St Denis
*
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* LibTomMath is a library that provides multiple-precision
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* integer arithmetic as well as number theoretic functionality.
*
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* The library was designed directly after the MPI library by
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* 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, tstdenis82@gmail.com, http://libtom.org
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*/
/* c = a mod b, 0 <= c < b if b > 0, b < c <= 0 if b < 0 */
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int
mp_mod (mp_int * a, mp_int * b, mp_int * c)
{
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mp_int t;
int res;
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if ((res = mp_init_size(&t, b->used)) != MP_OKAY) {
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return res;
}
if ((res = mp_div(a, b, NULL, &t)) != MP_OKAY) {
mp_clear(&t);
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return res;
}
if ((mp_iszero(&t) != MP_NO) || (t.sign == b->sign)) {
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res = MP_OKAY;
mp_exch(&t, c);
} else {
res = mp_add(b, &t, c);
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}
mp_clear(&t);
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return res;
}
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#endif
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/* ref: $Format:%D$ */
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