glibc/stdlib/mul_1.c

59 lines
1.7 KiB
C
Raw Normal View History

/* mpn_mul_1 -- Multiply a limb vector with a single limb and
1995-02-18 09:27:10 +08:00
store the product in a second limb vector.
Copyright (C) 1991-2014 Free Software Foundation, Inc.
1995-02-18 09:27:10 +08:00
This file is part of the GNU MP Library.
The GNU MP Library is free software; you can redistribute it and/or modify
2001-07-07 18:13:33 +08:00
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or (at your
1995-02-18 09:27:10 +08:00
option) any later version.
The GNU MP Library is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
2001-07-07 18:13:33 +08:00
or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
1995-02-18 09:27:10 +08:00
License for more details.
2001-07-07 18:13:33 +08:00
You should have received a copy of the GNU Lesser General Public License
along with the GNU MP Library; see the file COPYING.LIB. If not, see
<http://www.gnu.org/licenses/>. */
1995-02-18 09:27:10 +08:00
2005-12-14 23:06:39 +08:00
#include <gmp.h>
1995-02-18 09:27:10 +08:00
#include "gmp-impl.h"
#include "longlong.h"
1996-05-08 05:04:52 +08:00
mp_limb_t
mpn_mul_1 (res_ptr, s1_ptr, s1_size, s2_limb)
1995-02-18 09:27:10 +08:00
register mp_ptr res_ptr;
register mp_srcptr s1_ptr;
mp_size_t s1_size;
1996-05-08 05:04:52 +08:00
register mp_limb_t s2_limb;
1995-02-18 09:27:10 +08:00
{
1996-05-08 05:04:52 +08:00
register mp_limb_t cy_limb;
1995-02-18 09:27:10 +08:00
register mp_size_t j;
1996-05-08 05:04:52 +08:00
register mp_limb_t prod_high, prod_low;
1995-02-18 09:27:10 +08:00
/* The loop counter and index J goes from -S1_SIZE to -1. This way
the loop becomes faster. */
j = -s1_size;
/* Offset the base pointers to compensate for the negative indices. */
s1_ptr -= j;
res_ptr -= j;
cy_limb = 0;
do
{
umul_ppmm (prod_high, prod_low, s1_ptr[j], s2_limb);
prod_low += cy_limb;
cy_limb = (prod_low < cy_limb) + prod_high;
res_ptr[j] = prod_low;
}
while (++j != 0);
return cy_limb;
}