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/mpz/divis_2exp.c | 60 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 60 insertions(+) create mode 100644 gmp-6.3.0/mpz/divis_2exp.c (limited to 'gmp-6.3.0/mpz/divis_2exp.c') diff --git a/gmp-6.3.0/mpz/divis_2exp.c b/gmp-6.3.0/mpz/divis_2exp.c new file mode 100644 index 0000000..4ecb0c0 --- /dev/null +++ b/gmp-6.3.0/mpz/divis_2exp.c @@ -0,0 +1,60 @@ +/* mpz_divisible_2exp_p -- mpz by 2^n divisibility test + +Copyright 2001, 2002 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" + + +int +mpz_divisible_2exp_p (mpz_srcptr a, mp_bitcnt_t d) __GMP_NOTHROW +{ + mp_size_t i, dlimbs; + unsigned dbits; + mp_ptr ap; + mp_limb_t dmask; + mp_size_t asize; + + asize = ABSIZ(a); + dlimbs = d / GMP_NUMB_BITS; + + /* if d covers the whole of a, then only a==0 is divisible */ + if (asize <= dlimbs) + return asize == 0; + + /* whole limbs must be zero */ + ap = PTR(a); + for (i = 0; i < dlimbs; i++) + if (ap[i] != 0) + return 0; + + /* left over bits must be zero */ + dbits = d % GMP_NUMB_BITS; + dmask = (CNST_LIMB(1) << dbits) - 1; + return (ap[dlimbs] & dmask) == 0; +} -- cgit v1.2.3