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glibc/stdlib/addmul_1.c
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/* mpn_addmul_1 -- multiply the S1_SIZE long limb vector pointed to by S1_PTR | |
by S2_LIMB, add the S1_SIZE least significant limbs of the product to the | |
limb vector pointed to by RES_PTR. Return the most significant limb of | |
the product, adjusted for carry-out from the addition. | |
Copyright (C) 1992-2016 Free Software Foundation, Inc. | |
This file is part of the GNU MP Library. | |
The GNU MP Library is free software; you can redistribute it and/or modify | |
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 | |
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 | |
or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public | |
License for more details. | |
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/>. */ | |
#include <gmp.h> | |
#include "gmp-impl.h" | |
#include "longlong.h" | |
mp_limb_t | |
mpn_addmul_1 (register mp_ptr res_ptr, register mp_srcptr s1_ptr, | |
mp_size_t s1_size, register mp_limb_t s2_limb) | |
{ | |
register mp_limb_t cy_limb; | |
register mp_size_t j; | |
register mp_limb_t prod_high, prod_low; | |
register mp_limb_t x; | |
/* The loop counter and index J goes from -SIZE to -1. This way | |
the loop becomes faster. */ | |
j = -s1_size; | |
/* Offset the base pointers to compensate for the negative indices. */ | |
res_ptr -= j; | |
s1_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; | |
x = res_ptr[j]; | |
prod_low = x + prod_low; | |
cy_limb += (prod_low < x); | |
res_ptr[j] = prod_low; | |
} | |
while (++j != 0); | |
return cy_limb; | |
} |