Mercurial > dropbear
view libtommath/bn_mp_add.c @ 1719:25b0ce1936c4
changelog for 2020.79
author | Matt Johnston <matt@ucc.asn.au> |
---|---|
date | Mon, 15 Jun 2020 23:36:14 +0800 |
parents | 1051e4eea25a |
children |
line wrap: on
line source
#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