libtommath/mp_add.c
2019-10-29 19:30:23 +01:00

30 lines
833 B
C

#include "tommath_private.h"
#ifdef MP_ADD_C
/* LibTomMath, multiple-precision integer library -- Tom St Denis */
/* SPDX-License-Identifier: Unlicense */
/* high level addition (handles signs) */
mp_err mp_add(const mp_int *a, const mp_int *b, mp_int *c)
{
/* handle two cases, not four */
if (a->sign == b->sign) {
/* both positive or both negative */
/* add their magnitudes, copy the sign */
c->sign = a->sign;
return s_mp_add(a, b, c);
}
/* one positive, the other negative */
/* subtract the one with the greater magnitude from */
/* the one of the lesser magnitude. The result gets */
/* the sign of the one with the greater magnitude. */
if (mp_cmp_mag(a, b) == MP_LT) {
MP_EXCH(const mp_int *, a, b);
}
c->sign = a->sign;
return s_mp_sub(a, b, c);
}
#endif