1*181254a7Smrg /* mpn_add_n -- Add two limb vectors of equal, non-zero length.
2*181254a7Smrg
3*181254a7Smrg Copyright (C) 1992, 1993, 1994, 1996 Free Software Foundation, Inc.
4*181254a7Smrg
5*181254a7Smrg This file is part of the GNU MP Library.
6*181254a7Smrg
7*181254a7Smrg The GNU MP Library is free software; you can redistribute it and/or modify
8*181254a7Smrg it under the terms of the GNU Lesser General Public License as published by
9*181254a7Smrg the Free Software Foundation; either version 2.1 of the License, or (at your
10*181254a7Smrg option) any later version.
11*181254a7Smrg
12*181254a7Smrg The GNU MP Library is distributed in the hope that it will be useful, but
13*181254a7Smrg WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
14*181254a7Smrg or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
15*181254a7Smrg License for more details.
16*181254a7Smrg
17*181254a7Smrg You should have received a copy of the GNU Lesser General Public License
18*181254a7Smrg along with the GNU MP Library; see the file COPYING.LIB. If not, write to
19*181254a7Smrg the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
20*181254a7Smrg MA 02111-1307, USA. */
21*181254a7Smrg
22*181254a7Smrg #include <config.h>
23*181254a7Smrg #include "gmp-impl.h"
24*181254a7Smrg
25*181254a7Smrg mp_limb_t
26*181254a7Smrg #if __STDC__
mpn_add_n(mp_ptr res_ptr,mp_srcptr s1_ptr,mp_srcptr s2_ptr,mp_size_t size)27*181254a7Smrg mpn_add_n (mp_ptr res_ptr, mp_srcptr s1_ptr, mp_srcptr s2_ptr, mp_size_t size)
28*181254a7Smrg #else
29*181254a7Smrg mpn_add_n (res_ptr, s1_ptr, s2_ptr, size)
30*181254a7Smrg register mp_ptr res_ptr;
31*181254a7Smrg register mp_srcptr s1_ptr;
32*181254a7Smrg register mp_srcptr s2_ptr;
33*181254a7Smrg mp_size_t size;
34*181254a7Smrg #endif
35*181254a7Smrg {
36*181254a7Smrg register mp_limb_t x, y, cy;
37*181254a7Smrg register mp_size_t j;
38*181254a7Smrg
39*181254a7Smrg /* The loop counter and index J goes from -SIZE to -1. This way
40*181254a7Smrg the loop becomes faster. */
41*181254a7Smrg j = -size;
42*181254a7Smrg
43*181254a7Smrg /* Offset the base pointers to compensate for the negative indices. */
44*181254a7Smrg s1_ptr -= j;
45*181254a7Smrg s2_ptr -= j;
46*181254a7Smrg res_ptr -= j;
47*181254a7Smrg
48*181254a7Smrg cy = 0;
49*181254a7Smrg do
50*181254a7Smrg {
51*181254a7Smrg y = s2_ptr[j];
52*181254a7Smrg x = s1_ptr[j];
53*181254a7Smrg y += cy; /* add previous carry to one addend */
54*181254a7Smrg cy = (y < cy); /* get out carry from that addition */
55*181254a7Smrg y = x + y; /* add other addend */
56*181254a7Smrg cy = (y < x) + cy; /* get out carry from that add, combine */
57*181254a7Smrg res_ptr[j] = y;
58*181254a7Smrg }
59*181254a7Smrg while (++j != 0);
60*181254a7Smrg
61*181254a7Smrg return cy;
62*181254a7Smrg }
63