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#include "tommath_private.h"
#ifdef BN_MP_MUL_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.
*
* SPDX-License-Identifier: Unlicense
*/
/* high level multiplication (handles sign) */
int mp_mul(const mp_int *a, const mp_int *b, mp_int *c)
{
int res, neg;
neg = (a->sign == b->sign) ? MP_ZPOS : MP_NEG;
/* use Toom-Cook? */
#ifdef BN_MP_TOOM_MUL_C
if (MIN(a->used, b->used) >= TOOM_MUL_CUTOFF) {
res = mp_toom_mul(a, b, c);
} else
#endif
#ifdef BN_MP_KARATSUBA_MUL_C
/* use Karatsuba? */
if (MIN(a->used, b->used) >= KARATSUBA_MUL_CUTOFF) {
res = mp_karatsuba_mul(a, b, c);
} else
#endif
{
/* can we use the fast multiplier?
*
* The fast multiplier can be used if the output will
* have less than MP_WARRAY digits and the number of
* digits won't affect carry propagation
*/
int digs = a->used + b->used + 1;
#ifdef BN_FAST_S_MP_MUL_DIGS_C
if ((digs < (int)MP_WARRAY) &&
(MIN(a->used, b->used) <=
(int)(1u << (((size_t)CHAR_BIT * sizeof(mp_word)) - (2u * (size_t)DIGIT_BIT))))) {
res = fast_s_mp_mul_digs(a, b, c, digs);
} else
#endif
{
#ifdef BN_S_MP_MUL_DIGS_C
res = s_mp_mul(a, b, c); /* uses s_mp_mul_digs */
#else
res = MP_VAL;
#endif
}
}
c->sign = (c->used > 0) ? neg : MP_ZPOS;
return res;
}
#endif
/* ref: HEAD -> master, tag: v1.1.0 */
/* git commit: 08549ad6bc8b0cede0b357a9c341c5c6473a9c55 */
/* commit time: 2019-01-28 20:32:32 +0100 */
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