1/* mpn_addmul_1 -- multiply the S1_SIZE long limb vector pointed to by S1_PTR
2 by S2_LIMB, add the S1_SIZE least significant limbs of the product to the
3 limb vector pointed to by RES_PTR. Return the most significant limb of
4 the product, adjusted for carry-out from the addition.
5
6Copyright (C) 1992, 1993, 1994, 1996 Free Software Foundation, Inc.
7
8This file is part of the GNU MP Library.
9
10The GNU MP Library is free software; you can redistribute it and/or modify
11it under the terms of the GNU Lesser General Public License as published by
12the Free Software Foundation; either version 2.1 of the License, or (at your
13option) any later version.
14
15The GNU MP Library is distributed in the hope that it will be useful, but
16WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
17or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
18License for more details.
19
20You should have received a copy of the GNU Lesser General Public License
21along with the GNU MP Library; see the file COPYING.LIB. If not, write to
22the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
23MA 02111-1307, USA. */
24
25#include <config.h>
26#include "gmp-impl.h"
27
28mp_limb_t
29mpn_addmul_1 (res_ptr, s1_ptr, s1_size, s2_limb)
30 register mp_ptr res_ptr;
31 register mp_srcptr s1_ptr;
32 mp_size_t s1_size;
33 register mp_limb_t s2_limb;
34{
35 register mp_limb_t cy_limb;
36 register mp_size_t j;
37 register mp_limb_t prod_high, prod_low;
38 register mp_limb_t x;
39
40 /* The loop counter and index J goes from -SIZE to -1. This way
41 the loop becomes faster. */
42 j = -s1_size;
43
44 /* Offset the base pointers to compensate for the negative indices. */
45 res_ptr -= j;
46 s1_ptr -= j;
47
48 cy_limb = 0;
49 do
50 {
51 umul_ppmm (prod_high, prod_low, s1_ptr[j], s2_limb);
52
53 prod_low += cy_limb;
54 cy_limb = (prod_low < cy_limb) + prod_high;
55
56 x = res_ptr[j];
57 prod_low = x + prod_low;
58 cy_limb += (prod_low < x);
59 res_ptr[j] = prod_low;
60 }
61 while (++j != 0);
62
63 return cy_limb;
64}
65