contrib/gmp/mpf/fits_s.h

   1 /* mpf_fits_s*_p -- test whether an mpf fits a C signed type.
   2
   3 Copyright 2001, 2002 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
  23
  24 /* Notice this is equivalent to mpz_set_f + mpz_fits_s*_p.  */
  25
  26 int
  27 FUNCTION (mpf_srcptr f) __GMP_NOTHROW
  28 {
  29   mp_size_t  fs, fn;
  30   mp_srcptr  fp;
  31   mp_exp_t   exp;
  32   mp_limb_t  fl;
  33
  34   fs = SIZ(f);
  35   if (fs == 0)
  36     return 1;  /* zero fits */
  37
  38   exp = EXP(f);
  39   if (exp < 1)
  40     return 1;  /* -1 < f < 1 truncates to zero, so fits */
  41
  42   fp = PTR(f);
  43   fn = ABS (fs);
  44
  45   if (exp == 1)
  46     {
  47       fl = fp[fn-1];
  48     }
  49 #if GMP_NAIL_BITS != 0
  50   else if (exp == 2 && MAXIMUM > GMP_NUMB_MAX)
  51     {
  52       fl = fp[fn-1];
  53       if ((fl >> GMP_NAIL_BITS) != 0)
  54         return 0;
  55       fl = (fl << GMP_NUMB_BITS);
  56       if (fn >= 2)
  57         fl |= fp[fn-2];
  58     }
  59 #endif
  60   else
  61     return 0;
  62
  63   return fl <= (fs >= 0 ? (mp_limb_t) MAXIMUM : - (mp_limb_t) MINIMUM);
  64 }