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Diffstat (limited to 'Build/source/libs/mpfr/mpfr-3.1.2/src/uceil_log2.c')
-rw-r--r-- | Build/source/libs/mpfr/mpfr-3.1.2/src/uceil_log2.c | 63 |
1 files changed, 63 insertions, 0 deletions
diff --git a/Build/source/libs/mpfr/mpfr-3.1.2/src/uceil_log2.c b/Build/source/libs/mpfr/mpfr-3.1.2/src/uceil_log2.c new file mode 100644 index 00000000000..27f7d4fc784 --- /dev/null +++ b/Build/source/libs/mpfr/mpfr-3.1.2/src/uceil_log2.c @@ -0,0 +1,63 @@ +/* __gmpfr_ceil_log2 - returns ceil(log(d)/log(2)) + +Copyright 1999, 2000, 2001, 2002, 2003, 2004, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 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" + +/* returns ceil(log(d)/log(2)) if d > 0, + -1023 if d = +0, + and floor(log(-d)/log(2))+1 if d < 0*/ +long +__gmpfr_ceil_log2 (double d) +{ + long exp; +#if _GMP_IEEE_FLOATS + union ieee_double_extract x; + + x.d = d; + exp = x.s.exp - 1023; + x.s.exp = 1023; /* value for 1 <= d < 2 */ + if (x.d != 1.0) /* d: not a power of two? */ + exp++; + return exp; +#else + double m; + + if (d < 0.0) + return __gmpfr_floor_log2(-d)+1; + else if (d == 0.0) + return -1023; + else if (d >= 1.0) + { + exp = 0; + for( m= 1.0 ; m < d ; m *=2.0 ) + exp++; + } + else + { + exp = 1; + for( m= 1.0 ; m >= d ; m *= (1.0/2.0) ) + exp--; + } +#endif + return exp; +} + |