1 /* Software floating-point emulation.
2    Helper routine for _Q_* routines.
3    Simulate exceptions using double arithmetics.
4    Copyright (C) 1999 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, see
20    <http://www.gnu.org/licenses/>.  */
21 
22 #include "soft-fp.h"
23 
24 unsigned long long ___Q_numbers [] = {
25 0x0000000000000000ULL, /* Zero */
26 0x0010100000000000ULL, /* Very tiny number */
27 0x0010000000000000ULL, /* Minimum normalized number */
28 0x7fef000000000000ULL, /* A huge double number */
29 };
30 
___Q_simulate_exceptions(int exceptions)31 double ___Q_simulate_exceptions(int exceptions)
32 {
33   double d, *p = (double *)___Q_numbers;
34   if (exceptions & FP_EX_INVALID)
35     d = p[0]/p[0];
36   if (exceptions & FP_EX_OVERFLOW)
37     {
38       d = p[3] + p[3];
39       exceptions &= ~FP_EX_INEXACT;
40     }
41   if (exceptions & FP_EX_UNDERFLOW)
42     {
43       if (exceptions & FP_EX_INEXACT)
44         {
45 	  d = p[2] * p[2];
46 	  exceptions &= ~FP_EX_INEXACT;
47 	}
48       else
49 	d = p[1] - p[2];
50     }
51   if (exceptions & FP_EX_DIVZERO)
52     d = 1.0/p[0];
53   if (exceptions & FP_EX_INEXACT)
54     d = p[3] - p[2];
55   return d;
56 }
57