1 /* Cray PVP mpn_add_n -- add two limb vectors and store their sum in a third
4 Copyright 1996, 2000, 2001 Free Software Foundation, Inc.
6 This file is part of the GNU MP Library.
8 The GNU MP Library is free software; you can redistribute it and/or modify
9 it under the terms of the GNU Lesser General Public License as published by
10 the Free Software Foundation; either version 3 of the License, or (at your
11 option) any later version.
13 The GNU MP Library is distributed in the hope that it will be useful, but
14 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
15 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
16 License for more details.
18 You should have received a copy of the GNU Lesser General Public License
19 along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */
21 /* This code runs at 4 cycles/limb. It may be possible to bring it down
28 mpn_add_n (mp_ptr rp, mp_srcptr up, mp_srcptr vp, mp_size_t n)
31 mp_limb_t a, b, r, s0, c0, c1;
35 /* Main add loop. Generate a raw output sum in rp[] and a carry vector
38 for (i = 0; i < n; i++)
44 c0 = ((a & b) | ((a | b) & ~s0)) >> 63;
47 /* Carry add loop. Add the carry vector cy[] to the raw sum rp[] and
48 store the new sum back to rp[0]. If this generates further carry, set
52 for (i = 1; i < n; i++)
61 /* If that second loop generated carry, handle that in scalar loop. */
65 /* Look for places where rp[k] is zero and cy[k-1] is non-zero.
66 These are where we got a recurrency carry. */
67 for (i = 1; i < n; i++)
70 c0 = (r == 0 && cy[i - 1] != 0);
76 return cyrec | cy[n - 1];