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git-svn-id: file:///srv/svn/repos/haiku/buildtools/trunk@29042 a95241bf-73f2-0310-859d-f6bbb57e9c96
78 lines
2.2 KiB
C
78 lines
2.2 KiB
C
/* mpfr_fits_*_p -- test whether an mpfr fits a C signed type.
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Copyright 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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Copied from mpf/fits_s.h.
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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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FUNCTION (mpfr_srcptr f, mp_rnd_t rnd)
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{
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mp_exp_t exp;
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mp_prec_t prec;
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TYPE s;
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mpfr_t x;
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int neg;
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int res;
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if (MPFR_UNLIKELY (MPFR_IS_SINGULAR (f)))
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/* Zero always fit */
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return MPFR_IS_ZERO (f) ? 1 : 0;
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/* now it fits if either
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(a) MINIMUM <= f <= MAXIMUM
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(b) or MINIMUM <= round(f, prec(slong), rnd) <= MAXIMUM */
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exp = MPFR_GET_EXP (f);
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if (exp < 1)
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return 1; /* |f| < 1: always fits */
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neg = MPFR_IS_NEG (f);
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/* let EXTREMUM be MAXIMUM if f > 0, and MINIMUM if f < 0 */
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/* first compute prec(EXTREMUM), this could be done at configure time */
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s = (neg) ? MINIMUM : MAXIMUM;
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for (prec = 0; s != 0; s /= 2, prec ++);
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/* EXTREMUM needs prec bits, i.e. 2^(prec-1) <= |EXTREMUM| < 2^prec */
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/* if exp < prec - 1, then f < 2^(prec-1) < |EXTREMUM| */
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if ((mpfr_prec_t) exp < prec - 1)
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return 1;
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/* if exp > prec + 1, then f >= 2^prec > EXTREMUM */
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if ((mpfr_prec_t) exp > prec + 1)
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return 0;
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/* remains cases exp = prec-1 to prec+1 */
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/* hard case: first round to prec bits, then check */
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mpfr_init2 (x, prec);
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mpfr_set (x, f, rnd);
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res = (neg) ? (mpfr_cmp_si (x, MINIMUM) >= 0)
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: (mpfr_cmp_si (x, MAXIMUM) <= 0);
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mpfr_clear (x);
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return res;
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}
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