### view libtommath/bn_mp_add.c @ 763:f744321ac048ecc

ecdh works against OpenSSH
author Matt Johnston Mon, 08 Apr 2013 23:12:20 +0800 5ff8218bcee9 60fc6476e044
line wrap: on
line source
```#include <tommath.h>
/* 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.
*
* The library is free for all purposes without any express
* guarantee it works.
*
* Tom St Denis, [email protected], http://math.libtomcrypt.com
*/

/* high level addition (handles signs) */
int mp_add (mp_int * a, mp_int * b, mp_int * c)
{
int     sa, sb, res;

/* 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;
res = 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;
res = s_mp_sub (b, a, c);
} else {
c->sign = sa;
res = s_mp_sub (a, b, c);
}
}
return res;
}

#endif

/* \$Source: /cvs/libtom/libtommath/bn_mp_add.c,v \$ */
/* \$Revision: 1.3 \$ */
/* \$Date: 2006/03/31 14:18:44 \$ */
```