1 /* mpn_addcnd_n -- Compute R = U + V if CND != 0 or R = U if CND == 0.
2 Both cases should take the same time and perform the exact same memory
3 accesses, since this function is intended to be used where side-channel
4 attack resilience is relevant.
6 THIS IS AN INTERNAL FUNCTION WITH A MUTABLE INTERFACE. IT IS ONLY
7 SAFE TO REACH THIS FUNCTION THROUGH DOCUMENTED INTERFACES.
9 Copyright 1992, 1993, 1994, 1996, 2000, 2002, 2008, 2009, 2011 Free Software
12 This file is part of the GNU MP Library.
14 The GNU MP Library is free software; you can redistribute it and/or modify
15 it under the terms of the GNU Lesser General Public License as published by
16 the Free Software Foundation; either version 3 of the License, or (at your
17 option) any later version.
19 The GNU MP Library is distributed in the hope that it will be useful, but
20 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
21 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
22 License for more details.
24 You should have received a copy of the GNU Lesser General Public License
25 along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */
31 mpn_addcnd_n (mp_ptr rp, mp_srcptr up, mp_srcptr vp, mp_size_t n, mp_limb_t cnd)
33 mp_limb_t ul, vl, sl, rl, cy, cy1, cy2, mask;
36 ASSERT (MPN_SAME_OR_SEPARATE_P (rp, up, n));
37 ASSERT (MPN_SAME_OR_SEPARATE_P (rp, vp, n));
39 mask = -(mp_limb_t) (cnd != 0);
45 #if GMP_NAIL_BITS == 0
55 cy = rl >> GMP_NUMB_BITS;
56 *rp++ = rl & GMP_NUMB_MASK;