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author | Jakub Jelinek <jakub@redhat.com> | 2007-07-12 18:26:36 +0000 |
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committer | Jakub Jelinek <jakub@redhat.com> | 2007-07-12 18:26:36 +0000 |
commit | 0ecb606cb6cf65de1d9fc8a919bceb4be476c602 (patch) | |
tree | 2ea1f8305970753e4a657acb2ccc15ca3eec8e2c /stdlib/submul_1.c | |
parent | 7d58530341304d403a6626d7f7a1913165fe2f32 (diff) | |
download | glibc-0ecb606cb6cf65de1d9fc8a919bceb4be476c602.zip glibc-0ecb606cb6cf65de1d9fc8a919bceb4be476c602.tar.gz glibc-0ecb606cb6cf65de1d9fc8a919bceb4be476c602.tar.bz2 |
2.5-18.1
Diffstat (limited to 'stdlib/submul_1.c')
-rw-r--r-- | stdlib/submul_1.c | 65 |
1 files changed, 65 insertions, 0 deletions
diff --git a/stdlib/submul_1.c b/stdlib/submul_1.c new file mode 100644 index 0000000..3e7163a --- /dev/null +++ b/stdlib/submul_1.c @@ -0,0 +1,65 @@ +/* mpn_submul_1 -- multiply the S1_SIZE long limb vector pointed to by S1_PTR + by S2_LIMB, subtract the S1_SIZE least significant limbs of the product + from the limb vector pointed to by RES_PTR. Return the most significant + limb of the product, adjusted for carry-out from the subtraction. + +Copyright (C) 1992, 1993, 1994, 1996, 2005 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, write to +the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, +MA 02111-1307, USA. */ + +#include <gmp.h> +#include "gmp-impl.h" +#include "longlong.h" + +mp_limb_t +mpn_submul_1 (res_ptr, s1_ptr, s1_size, s2_limb) + 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; +} |