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Annotation of OpenXM_contrib/gmp/mpfr/mul_2si.c, Revision 1.1

1.1     ! ohara       1: /* mpfr_mul_2si -- multiply a floating-point number by a power of two
        !             2:
        !             3: Copyright 1999, 2001, 2002 Free Software Foundation, Inc.
        !             4:
        !             5: This file is part of the MPFR Library.
        !             6:
        !             7: The MPFR Library is free software; you can redistribute it and/or modify
        !             8: it under the terms of the GNU Lesser General Public License as published by
        !             9: the Free Software Foundation; either version 2.1 of the License, or (at your
        !            10: option) any later version.
        !            11:
        !            12: The MPFR Library is distributed in the hope that it will be useful, but
        !            13: WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
        !            14: or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
        !            15: License for more details.
        !            16:
        !            17: You should have received a copy of the GNU Lesser General Public License
        !            18: along with the MPFR Library; see the file COPYING.LIB.  If not, write to
        !            19: the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
        !            20: MA 02111-1307, USA. */
        !            21:
        !            22: #include "gmp.h"
        !            23: #include "gmp-impl.h"
        !            24: #include "mpfr.h"
        !            25: #include "mpfr-impl.h"
        !            26:
        !            27:
        !            28: /* In the overflow test "n > emax - emin" ensures "emax-n" doesn't wrap
        !            29:    around if n is big.  It used to done with "emax < MPFR_EMIN_MIN + n", but
        !            30:    that provoked a compiler bug on mips gcc 2.95.3 in -O2 -mabi=n32.
        !            31:    Similarly for the underflow test.  */
        !            32:
        !            33: int
        !            34: mpfr_mul_2si (mpfr_ptr y, mpfr_srcptr x, long int n, mp_rnd_t rnd_mode)
        !            35: {
        !            36:   int inexact;
        !            37:
        !            38:   inexact = y != x ? mpfr_set (y, x, rnd_mode) : 0;
        !            39:
        !            40:   if (MPFR_IS_FP(y) && MPFR_NOTZERO(y))
        !            41:     {
        !            42:       if (n > 0
        !            43:           && ((unsigned long) n >
        !            44:               (unsigned long) (mp_exp_unsigned_t) (__mpfr_emax - __mpfr_emin)
        !            45:               || MPFR_EXP(y) > __mpfr_emax - n))
        !            46:         return mpfr_set_overflow (y, rnd_mode, MPFR_SIGN(y));
        !            47:
        !            48:       if (n < 0
        !            49:           && ((unsigned long) -n >
        !            50:               (unsigned long) (mp_exp_unsigned_t) (__mpfr_emax - __mpfr_emin)
        !            51:               || MPFR_EXP(y) < __mpfr_emin - n))
        !            52:         return mpfr_set_underflow (y, rnd_mode, MPFR_SIGN(y));
        !            53:
        !            54:       MPFR_EXP(y) += n;
        !            55:     }
        !            56:
        !            57:   return inexact;
        !            58: }