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Annotation of OpenXM_contrib/gmp/insert-double.c, Revision 1.1.1.1

1.1       maekawa     1: /* __gmp_insert_double -- convert from array of mp_limb_t to double.
                      2:
                      3: Copyright (C) 1996 Free Software Foundation, Inc.
                      4:
                      5: This file is part of the GNU MP Library.
                      6:
                      7: The GNU MP Library is free software; you can redistribute it and/or modify
                      8: it under the terms of the GNU Library General Public License as published by
                      9: the Free Software Foundation; either version 2 of the License, or (at your
                     10: option) any later version.
                     11:
                     12: The GNU MP 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 Library General Public
                     15: License for more details.
                     16:
                     17: You should have received a copy of the GNU Library General Public License
                     18: along with the GNU MP 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:
                     25: #ifdef XDEBUG
                     26: #undef _GMP_IEEE_FLOATS
                     27: #endif
                     28:
                     29: #ifndef _GMP_IEEE_FLOATS
                     30: #define _GMP_IEEE_FLOATS 0
                     31: #endif
                     32:
                     33: double
                     34: #if __STDC__
                     35: __gmp_scale2 (double d, int exp)
                     36: #else
                     37: __gmp_scale2 (d, exp)
                     38:      double d;
                     39:      int exp;
                     40: #endif
                     41: {
                     42: #if _GMP_IEEE_FLOATS
                     43:   {
                     44:     union ieee_double_extract x;
                     45:     x.d = d;
                     46:     x.s.exp += exp;
                     47:     return x.d;
                     48:   }
                     49: #else
                     50:   {
                     51:     double factor, r;
                     52:
                     53:     factor = 2.0;
                     54:     if (exp < 0)
                     55:       {
                     56:        factor = 0.5;
                     57:        exp = -exp;
                     58:       }
                     59:     r = d;
                     60:     while (exp != 0)
                     61:       {
                     62:        if ((exp & 1) != 0)
                     63:          r *= factor;
                     64:        factor *= factor;
                     65:        exp >>= 1;
                     66:       }
                     67:     return r;
                     68:   }
                     69: #endif
                     70: }