1f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project#include <tommath.h> 2f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project#ifdef BN_MP_ADD_C 3f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/* LibTomMath, multiple-precision integer library -- Tom St Denis 4f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * 5f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * LibTomMath is a library that provides multiple-precision 6f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * integer arithmetic as well as number theoretic functionality. 7f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * 8f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * The library was designed directly after the MPI library by 9f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * Michael Fromberger but has been written from scratch with 10f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * additional optimizations in place. 11f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * 12f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * The library is free for all purposes without any express 13f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * guarantee it works. 14f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * 15f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * Tom St Denis, tomstdenis@gmail.com, http://math.libtomcrypt.com 16f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project */ 17f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 18f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/* high level addition (handles signs) */ 19f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Projectint mp_add (mp_int * a, mp_int * b, mp_int * c) 20f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project{ 21f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project int sa, sb, res; 22f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 23f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* get sign of both inputs */ 24f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project sa = a->sign; 25f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project sb = b->sign; 26f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 27f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* handle two cases, not four */ 28f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if (sa == sb) { 29f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* both positive or both negative */ 30f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* add their magnitudes, copy the sign */ 31f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project c->sign = sa; 32f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project res = s_mp_add (a, b, c); 33f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } else { 34f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* one positive, the other negative */ 35f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* subtract the one with the greater magnitude from */ 36f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* the one of the lesser magnitude. The result gets */ 37f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* the sign of the one with the greater magnitude. */ 38f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if (mp_cmp_mag (a, b) == MP_LT) { 39f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project c->sign = sb; 40f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project res = s_mp_sub (b, a, c); 41f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } else { 42f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project c->sign = sa; 43f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project res = s_mp_sub (a, b, c); 44f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 45f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 46f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project return res; 47f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project} 48f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 49f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project#endif 50f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 51f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/* $Source: /cvs/libtom/libtommath/bn_mp_add.c,v $ */ 52f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/* $Revision: 1.3 $ */ 53f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/* $Date: 2006/03/31 14:18:44 $ */ 54