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git-svn-id: file:///srv/svn/repos/haiku/buildtools/trunk@29042 a95241bf-73f2-0310-859d-f6bbb57e9c96
66 lines
1.6 KiB
C
66 lines
1.6 KiB
C
/* __gmpfr_ceil_exp2 - returns y >= 2^d
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Copyright 1999, 2000, 2001, 2002, 2003, 2004, 2006, 2007 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 MPFR Library.
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The 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 2.1 of the License, or (at your
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option) any later version.
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The 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 MPFR Library; see the file COPYING.LIB. If not, write to
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the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
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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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