mirror of
http://galexander.org/git/simplesshd.git
synced 2024-11-30 19:28:10 +00:00
54 lines
1.4 KiB
C
54 lines
1.4 KiB
C
|
#include <tommath.h>
|
||
|
|
#ifdef BN_MP_ADD_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.
|
||
|
|
*
|
||
|
|
* The library is free for all purposes without any express
|
||
|
|
* guarantee it works.
|
||
|
|
*
|
||
|
|
* Tom St Denis, tomstdenis@gmail.com, 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 $ */
|