ports/sysdeps/m68k/m680x0/fpu/s_frexp.c

   1 /* Copyright (C) 1996-2014 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library.  If not, see
  16    <http://www.gnu.org/licenses/>.  */
  17
  18 #include <math.h>
  19
  20 #ifndef FUNC
  21 #define FUNC frexp
  22 #endif
  23 #ifndef float_type
  24 #define float_type double
  25 #endif
  26
  27 #define __CONCATX(a,b) __CONCAT(a,b)
  28
  29 float_type
  30 __CONCATX(__,FUNC) (float_type value, int *expptr)
  31 {
  32   float_type mantissa, exponent;
  33   int iexponent;
  34   unsigned long fpsr;
  35
  36   __asm ("ftst%.x %1\n"
  37          "fmove%.l %/fpsr, %0"
  38          : "=dm" (fpsr) : "f" (value));
  39   if (fpsr & (7 << 24))
  40     {
  41       /* Not finite or zero.  */
  42       *expptr = 0;
  43       return value;
  44     }
  45   __asm ("fgetexp%.x %1, %0" : "=f" (exponent) : "f" (value));
  46   iexponent = (int) exponent + 1;
  47   *expptr = iexponent;
  48   __asm ("fscale%.l %2, %0"
  49          : "=f" (mantissa)
  50          : "0" (value), "dmi" (-iexponent));
  51   return mantissa;
  52 }
  53 weak_alias (__CONCATX(__,FUNC), FUNC)