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b58ddff026
* merged mpfr 3.0.0 and gmp 5.0.1 in buildtools trunk git-svn-id: file:///srv/svn/repos/haiku/buildtools/trunk@37378 a95241bf-73f2-0310-859d-f6bbb57e9c96
66 lines
1.7 KiB
C
66 lines
1.7 KiB
C
/* __gmpfr_ceil_exp2 - returns y >= 2^d
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Copyright 1999, 2000, 2001, 2002, 2003, 2004, 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
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Contributed by the Arenaire and Cacao projects, INRIA.
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This file is part of the GNU MPFR Library.
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The GNU MPFR Library is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 3 of the License, or (at your
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option) any later version.
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The GNU MPFR Library is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with the GNU MPFR Library; see the file COPYING.LESSER. If not, see
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http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
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51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */
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#include "mpfr-impl.h"
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/* returns y >= 2^d, assuming that d <= 1024
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for d integer, returns exactly 2^d
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*/
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double
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__gmpfr_ceil_exp2 (double d)
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{
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long exp;
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#if _GMP_IEEE_FLOATS
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union ieee_double_extract x;
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#else
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struct {double d;} x;
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#endif
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MPFR_ASSERTN(d <= 1024.0);
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exp = (long) d;
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if (d != (double) exp)
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exp++;
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/* now exp = ceil(d) */
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x.d = 1.0;
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#if _GMP_IEEE_FLOATS
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x.s.exp = exp <= -1022 ? 1 : 1023 + exp;
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#else
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if (exp >= 0)
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{
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while (exp != 0)
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{
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x.d *= 2.0;
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exp--;
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}
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}
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else
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{
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while (exp != 0)
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{
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x.d *= (1.0 / 2.0);
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exp++;
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}
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}
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#endif
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return x.d;
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}
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