efee5258bc
The MPFR library is a C library for multiple-precision floating-point computations with exact rounding (also called correct rounding). It is based on the GMP multiple-precision library and should replace the MPF class in further releases of GMP. GCC >= 4.2 requires MPFR.
73 lines
2.3 KiB
C
73 lines
2.3 KiB
C
/* mpfr_set_ui_2exp -- set a MPFR number from a machine unsigned integer with
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a shift
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Copyright 2004, 2006, 2007, 2008, 2009, 2010, 2011 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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#define MPFR_NEED_LONGLONG_H
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#include "mpfr-impl.h"
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int
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mpfr_set_ui_2exp (mpfr_ptr x, unsigned long i, mpfr_exp_t e, mpfr_rnd_t rnd_mode)
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{
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MPFR_SET_POS (x);
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if (i == 0)
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{
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MPFR_SET_ZERO (x);
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MPFR_RET (0);
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}
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else
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{
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mp_size_t xn;
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unsigned int cnt, nbits;
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mp_limb_t *xp;
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int inex = 0;
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/* FIXME: support int limbs (e.g. 16-bit limbs on 16-bit proc) */
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MPFR_ASSERTD (i == (mp_limb_t) i);
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/* Position of the highest limb */
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xn = (MPFR_PREC (x) - 1) / GMP_NUMB_BITS;
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count_leading_zeros (cnt, (mp_limb_t) i);
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MPFR_ASSERTD (cnt < GMP_NUMB_BITS); /* OK since i != 0 */
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xp = MPFR_MANT(x);
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xp[xn] = ((mp_limb_t) i) << cnt;
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/* Zero the xn lower limbs. */
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MPN_ZERO(xp, xn);
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nbits = GMP_NUMB_BITS - cnt;
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e += nbits; /* exponent _before_ the rounding */
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/* round if MPFR_PREC(x) smaller than length of i */
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if (MPFR_UNLIKELY (MPFR_PREC (x) < nbits) &&
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MPFR_UNLIKELY (mpfr_round_raw (xp + xn, xp + xn, nbits, 0,
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MPFR_PREC (x), rnd_mode, &inex)))
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{
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e++;
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xp[xn] = MPFR_LIMB_HIGHBIT;
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}
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MPFR_EXP (x) = e;
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return mpfr_check_range (x, inex, rnd_mode);
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}
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}
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