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Diffstat (limited to 'Build/source/libs/mpfr/mpfr-src/src/powerof2.c')
-rw-r--r-- | Build/source/libs/mpfr/mpfr-src/src/powerof2.c | 49 |
1 files changed, 49 insertions, 0 deletions
diff --git a/Build/source/libs/mpfr/mpfr-src/src/powerof2.c b/Build/source/libs/mpfr/mpfr-src/src/powerof2.c new file mode 100644 index 00000000000..bacbcdcf6e4 --- /dev/null +++ b/Build/source/libs/mpfr/mpfr-src/src/powerof2.c @@ -0,0 +1,49 @@ +/* mpfr_powerof2_raw -- test whether a floating-point number is a power of 2 + +Copyright 2002-2015 Free Software Foundation, Inc. +Contributed by the AriC and Caramel projects, INRIA. + +This file is part of the GNU MPFR Library. + +The GNU MPFR 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 3 of the License, or (at your +option) any later version. + +The GNU MPFR 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 MPFR Library; see the file COPYING.LESSER. If not, see +http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc., +51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */ + +#include "mpfr-impl.h" + +/* This is an internal function and one assumes that x is a non-special + * number (more precisely, only its significand is considered and this + * function can be used even if the exponent field of x has not been + * initialized). It returns 1 (true) if |x| is a power of 2, else 0. + */ + +int +mpfr_powerof2_raw (mpfr_srcptr x) +{ + mp_limb_t *xp; + mp_size_t xn; + + /* This is an internal function, and we may call it with some + wrong numbers (ie good mantissa but wrong flags or exp) + So we don't want to test if it is a pure FP. + MPFR_ASSERTN(MPFR_IS_PURE_FP(x)); */ + xp = MPFR_MANT(x); + xn = (MPFR_PREC(x) - 1) / GMP_NUMB_BITS; + if (xp[xn] != MPFR_LIMB_HIGHBIT) + return 0; + while (xn > 0) + if (xp[--xn] != 0) + return 0; + return 1; +} |