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Annotation of OpenXM_contrib/gmp/mpf/get_d.c, Revision 1.1.1.1

1.1       maekawa     1: /* double mpf_get_d (mpf_t src) -- Return the double approximation to SRC.
                      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: double
                     26: #if __STDC__
                     27: mpf_get_d (mpf_srcptr src)
                     28: #else
                     29: mpf_get_d (src)
                     30:      mpf_srcptr src;
                     31: #endif
                     32: {
                     33:   double res;
                     34:   mp_size_t size, i, n_limbs_to_use;
                     35:   int negative;
                     36:   mp_ptr qp;
                     37:
                     38:   size = SIZ(src);
                     39:   if (size == 0)
                     40:     return 0.0;
                     41:
                     42:   negative = size < 0;
                     43:   size = ABS (size);
                     44:   qp = PTR(src);
                     45:
                     46:   res = qp[size - 1];
                     47:   n_limbs_to_use = MIN (LIMBS_PER_DOUBLE, size);
                     48:   for (i = 2; i <= n_limbs_to_use; i++)
                     49:     res = res * MP_BASE_AS_DOUBLE + qp[size - i];
                     50:
                     51:   res = __gmp_scale2 (res, (EXP(src) - n_limbs_to_use) * BITS_PER_MP_LIMB);
                     52:
                     53:   return negative ? -res : res;
                     54: }