From 11da511c784eca003deb90c23570f0873954e0de Mon Sep 17 00:00:00 2001 From: Duncan Wilkie Date: Sat, 18 Nov 2023 06:11:09 -0600 Subject: Initial commit. --- gmp-6.3.0/mpn/generic/gcd_11.c | 74 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 74 insertions(+) create mode 100644 gmp-6.3.0/mpn/generic/gcd_11.c (limited to 'gmp-6.3.0/mpn/generic/gcd_11.c') diff --git a/gmp-6.3.0/mpn/generic/gcd_11.c b/gmp-6.3.0/mpn/generic/gcd_11.c new file mode 100644 index 0000000..214e45c --- /dev/null +++ b/gmp-6.3.0/mpn/generic/gcd_11.c @@ -0,0 +1,74 @@ +/* mpn_gcd_11 -- limb greatest common divisor. + +Copyright 1994, 1996, 2000, 2001, 2009, 2012, 2019 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 either: + + * the GNU Lesser General Public License as published by the Free + Software Foundation; either version 3 of the License, or (at your + option) any later version. + +or + + * the GNU General Public License as published by the Free Software + Foundation; either version 2 of the License, or (at your option) any + later version. + +or both in parallel, as here. + +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 General Public License +for more details. + +You should have received copies of the GNU General Public License and the +GNU Lesser General Public License along with the GNU MP Library. If not, +see https://www.gnu.org/licenses/. */ + +#include "gmp-impl.h" +#include "longlong.h" + +mp_limb_t +mpn_gcd_11 (mp_limb_t u, mp_limb_t v) +{ + ASSERT (u & v & 1); + + /* In this loop, we represent the odd numbers ulimb and vlimb + without the redundant least significant one bit. This reduction + in size by one bit ensures that the high bit of t, below, is set + if and only if vlimb > ulimb. */ + + u >>= 1; + v >>= 1; + + while (u != v) + { + mp_limb_t t; + mp_limb_t vgtu; + int c; + + t = u - v; + vgtu = LIMB_HIGHBIT_TO_MASK (t); + + /* v <-- min (u, v) */ + v += (vgtu & t); + + /* u <-- |u - v| */ + u = (t ^ vgtu) - vgtu; + + count_trailing_zeros (c, t); + /* We have c <= GMP_LIMB_BITS - 2 here, so that + + ulimb >>= (c + 1); + + would be safe. But unlike the addition c + 1, a separate + shift by 1 is independent of c, and can be executed in + parallel with count_trailing_zeros. */ + u = (u >> 1) >> c; + } + return (u << 1) + 1; +} -- cgit v1.2.3