Return to mul_2si.c CVS log

Up to [local] / OpenXM_contrib / gmp / mpfr

Annotation of OpenXM_contrib/gmp/mpfr/mul_2si.c, Revision 1.1.1.1

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: }