diff options
Diffstat (limited to 'Build/source/libs/mpfr/mpfr-src/src/odd_p.c')
-rw-r--r-- | Build/source/libs/mpfr/mpfr-src/src/odd_p.c | 73 |
1 files changed, 73 insertions, 0 deletions
diff --git a/Build/source/libs/mpfr/mpfr-src/src/odd_p.c b/Build/source/libs/mpfr/mpfr-src/src/odd_p.c new file mode 100644 index 00000000000..411f8555dbf --- /dev/null +++ b/Build/source/libs/mpfr/mpfr-src/src/odd_p.c @@ -0,0 +1,73 @@ +/* mpfr_odd_p -- check for odd integers + +Copyright 2001-2017 Free Software Foundation, Inc. +Contributed by the AriC and Caramba 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. */ + +#define MPFR_NEED_LONGLONG_H +#include "mpfr-impl.h" + +/* Return 1 if y is an odd integer, 0 otherwise. + Assumes y is not singular. */ +int +mpfr_odd_p (mpfr_srcptr y) +{ + mpfr_exp_t expo; + mpfr_prec_t prec; + mp_size_t yn; + mp_limb_t *yp; + + /* NAN, INF or ZERO are not allowed */ + MPFR_ASSERTD (!MPFR_IS_SINGULAR (y)); + + expo = MPFR_GET_EXP (y); + if (expo <= 0) + return 0; /* |y| < 1 and not 0 */ + + prec = MPFR_PREC(y); + if ((mpfr_prec_t) expo > prec) + return 0; /* y is a multiple of 2^(expo-prec), thus not odd */ + + /* 0 < expo <= prec: + y = 1xxxxxxxxxt.zzzzzzzzzzzzzzzzzz[000] + expo bits (prec-expo) bits + + We have to check that: + (a) the bit 't' is set + (b) all the 'z' bits are zero + */ + + prec = MPFR_PREC2LIMBS (prec) * GMP_NUMB_BITS - expo; + /* number of z+0 bits */ + + yn = prec / GMP_NUMB_BITS; + MPFR_ASSERTN(yn >= 0); + /* yn is the index of limb containing the 't' bit */ + + yp = MPFR_MANT(y); + /* if expo is a multiple of GMP_NUMB_BITS, t is bit 0 */ + if (expo % GMP_NUMB_BITS == 0 ? (yp[yn] & 1) == 0 + : yp[yn] << ((expo % GMP_NUMB_BITS) - 1) != MPFR_LIMB_HIGHBIT) + return 0; + while (--yn >= 0) + if (yp[yn] != 0) + return 0; + return 1; +} + |