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authorMatt Johnston <matt@ucc.asn.au>2007-01-11 04:29:08 +0000
committerMatt Johnston <matt@ucc.asn.au>2007-01-11 04:29:08 +0000
commit943636c3e13f50bc0e29c5f69974541a296a3be2 (patch)
tree02a55d7bff75c51e641a556ad331460a1d1270b6 /libtommath/bn_mp_add.c
parent0a60ef26bd13e6007c4fdd0f09b5a8d4785113c0 (diff)
parent9d5ed350a749368c84254c11e7616ce3c891193a (diff)
propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head c1db4398d56c56c6d06ae1e20c1e0d04dbb598ed)
to branch 'au.asn.ucc.matt.dropbear' (head d26d5eb2837f46b56a33fb0e7573aa0201abd4d5) --HG-- extra : convert_revision : 7a0ae6de81402591a789486070007238169fafca
Diffstat (limited to 'libtommath/bn_mp_add.c')
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diff --git a/libtommath/bn_mp_add.c b/libtommath/bn_mp_add.c
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+#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 $ */