sysdeps/powerpc/soft-fp/q_util.c

   1 /* Software floating-point emulation.
   2    Helper routine for _q_* routines.
   3    Simulate exceptions using double arithmetics.
   4    Copyright (C) 1999, 2000 Free Software Foundation, Inc.
   5    This file is part of the GNU C Library.
   6    Contributed by Jakub Jelinek (jj@ultra.linux.cz).
   7
   8    The GNU C Library is free software; you can redistribute it and/or
   9    modify it under the terms of the GNU Lesser General Public
  10    License as published by the Free Software Foundation; either
  11    version 2.1 of the License, or (at your option) any later version.
  12
  13    The GNU C Library is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16    Lesser General Public License for more details.
  17
  18    You should have received a copy of the GNU Lesser General Public
  19    License along with the GNU C Library; if not, write to the Free
  20    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  21    02111-1307 USA.  */
  22
  23 #include "soft-fp.h"
  24
  25 unsigned long long ___q_numbers [] = {
  26 0x0000000000000000ULL, /* Zero */
  27 0x0010100000000000ULL, /* Very tiny number */
  28 0x0010000000000000ULL, /* Minimum normalized number */
  29 0x7fef000000000000ULL, /* A huge double number */
  30 };
  31
  32 double ___q_simulate_exceptions(int exceptions)
  33 {
  34   double d, *p = (double *)___q_numbers;
  35   if (exceptions & FP_EX_INVALID)
  36     d = p[0]/p[0];
  37   if (exceptions & FP_EX_OVERFLOW)
  38     {
  39       d = p[3] + p[3];
  40       exceptions &= ~FP_EX_INEXACT;
  41     }
  42   if (exceptions & FP_EX_UNDERFLOW)
  43     {
  44       if (exceptions & FP_EX_INEXACT)
  45         {
  46           d = p[2] * p[2];
  47           exceptions &= ~FP_EX_INEXACT;
  48         }
  49       else
  50         d = p[1] - p[2];
  51     }
  52   if (exceptions & FP_EX_DIVZERO)
  53     d = 1.0/p[0];
  54   if (exceptions & FP_EX_INEXACT)
  55     d = p[3] - p[2];
  56   return d;
  57 }