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#include "tommath_private.h"
#ifdef BN_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)
{
mp_sign sa, sb;
mp_err err;
/* get sign of both inputs */
sa = a->sign;
sb = b->sign;
/* handle two cases, not four */
if (sa == sb) {
/* both positive or both negative */
/* add their magnitudes, copy the sign */
c->sign = sa;
err = s_mp_add(a, b, c);
} else {
/* 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) {
c->sign = sb;
err = s_mp_sub(b, a, c);
} else {
c->sign = sa;
err = s_mp_sub(a, b, c);
}
}
return err;
}
#endif
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