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git-svn-id: file:///srv/svn/repos/haiku/buildtools/trunk@29042 a95241bf-73f2-0310-859d-f6bbb57e9c96
61 lines
2.0 KiB
C
61 lines
2.0 KiB
C
/* mpfr_mul_2ui -- multiply a floating-point number by a power of two
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Copyright 1999, 2001, 2002, 2003, 2004, 2005, 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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int
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mpfr_mul_2ui (mpfr_ptr y, mpfr_srcptr x, unsigned long int n, mp_rnd_t rnd_mode)
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{
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int inexact;
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inexact = MPFR_UNLIKELY(y != x) ? mpfr_set (y, x, rnd_mode) : 0;
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if (MPFR_LIKELY( MPFR_IS_PURE_FP(y)) )
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{
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/* n will have to be casted to long to make sure that the addition
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and subtraction below (for overflow detection) are signed */
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while (MPFR_UNLIKELY(n > LONG_MAX))
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{
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int inex2;
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n -= LONG_MAX;
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inex2 = mpfr_mul_2ui(y, y, LONG_MAX, rnd_mode);
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if (inex2)
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return inex2; /* overflow */
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}
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/* MPFR_EMIN_MIN + (long) n is signed and doesn't lead to an overflow;
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the first test useful so that the real test can't lead to an
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overflow. */
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{
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mp_exp_t exp = MPFR_GET_EXP (y);
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if (MPFR_UNLIKELY( __gmpfr_emax < MPFR_EMIN_MIN + (long) n ||
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exp > __gmpfr_emax - (long) n))
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return mpfr_overflow (y, rnd_mode, MPFR_SIGN(y));
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MPFR_SET_EXP (y, exp + (long) n);
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}
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}
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return inexact;
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}
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