contrib/gmp/mpz/get_d_2exp.c

   1 /* double mpz_get_d_2exp (signed long int *exp, mpz_t src).
   2
   3 Copyright 2001, 2003, 2004 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 Lesser General Public License as published by
   9 the Free Software Foundation; either version 3 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 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 GNU MP Library.  If not, see http://www.gnu.org/licenses/.  */
  19
  20 #include "gmp.h"
  21 #include "gmp-impl.h"
  22 #include "longlong.h"
  23
  24 double
  25 mpz_get_d_2exp (signed long int *exp2, mpz_srcptr src)
  26 {
  27   mp_size_t size, abs_size;
  28   mp_srcptr ptr;
  29   int cnt;
  30   long exp;
  31
  32   size = SIZ(src);
  33   if (UNLIKELY (size == 0))
  34     {
  35       *exp2 = 0;
  36       return 0.0;
  37     }
  38
  39   ptr = PTR(src);
  40   abs_size = ABS(size);
  41   count_leading_zeros (cnt, ptr[abs_size - 1]);
  42   exp = abs_size * GMP_NUMB_BITS - (cnt - GMP_NAIL_BITS);
  43   *exp2 = exp;
  44   return mpn_get_d (ptr, abs_size, size, -exp);
  45 }