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Diffstat (limited to 'Build/source/libs/mpfr/mpfr-src/src/extract.c')
-rw-r--r-- | Build/source/libs/mpfr/mpfr-src/src/extract.c | 55 |
1 files changed, 55 insertions, 0 deletions
diff --git a/Build/source/libs/mpfr/mpfr-src/src/extract.c b/Build/source/libs/mpfr/mpfr-src/src/extract.c new file mode 100644 index 00000000000..c3bb0190276 --- /dev/null +++ b/Build/source/libs/mpfr/mpfr-src/src/extract.c @@ -0,0 +1,55 @@ +/* mpfr_extract -- bit-extraction function for the binary splitting algorithm + +Copyright 2000-2002, 2004-2015 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" + +/* given 0 <= |p| < 1, this function extracts limbs of p and puts them in y. + It is mainly designed for the "binary splitting" algorithm. + + More precisely, if B = 2^GMP_NUMB_BITS: + - for i=0, y = floor(p * B) + - for i>0, y = (p * B^(2^i)) mod B^(2^(i-1)) + */ + +void +mpfr_extract (mpz_ptr y, mpfr_srcptr p, unsigned int i) +{ + unsigned long two_i = 1UL << i; + unsigned long two_i_2 = i ? two_i / 2 : 1; + mp_size_t size_p = MPFR_LIMB_SIZE (p); + + /* as 0 <= |p| < 1, we don't have to care with infinities, NaN, ... */ + MPFR_ASSERTD (!MPFR_IS_SINGULAR (p)); + + _mpz_realloc (y, two_i_2); + if ((mpfr_uexp_t) size_p < two_i) + { + MPN_ZERO (PTR(y), two_i_2); + if ((mpfr_uexp_t) size_p >= two_i_2) + MPN_COPY (PTR(y) + two_i - size_p, MPFR_MANT(p), size_p - two_i_2); + } + else + MPN_COPY (PTR(y), MPFR_MANT(p) + size_p - two_i, two_i_2); + + MPN_NORMALIZE (PTR(y), two_i_2); + SIZ(y) = (MPFR_IS_NEG (p)) ? -two_i_2 : two_i_2; +} |