sysdeps/alpha/fpu/fraiseexcpt.c

   1 /* Raise given exceptions.
   2    Copyright (C) 1997 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Richard Henderson <rth@tamu.edu>, 1997.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Library General Public License as
   8    published by the Free Software Foundation; either version 2 of the
   9    License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Library General Public License for more details.
  15
  16    You should have received a copy of the GNU Library General Public
  17    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  18    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19    Boston, MA 02111-1307, USA.  */
  20
  21 #include <fenv.h>
  22 #include <math.h>
  23
  24 void
  25 feraiseexcept (int excepts)
  26 {
  27   double tmp;
  28
  29   /* Raise exceptions represented by EXPECTS.  But we must raise only
  30      one signal at a time.  It is important the if the overflow/underflow
  31      exception and the inexact exception are given at the same time,
  32      the overflow/underflow exception precedes the inexact exception.  */
  33
  34   /* We do these bits in assembly to be certain GCC doesn't optimize
  35      away something important.  */
  36
  37   /* First: invalid exception.  */
  38   if (FE_INVALID & excepts)
  39     {
  40       /* One example of a invalid operation is 0 * Infinity.  */
  41       __asm__ __volatile__("mult/sui $f31,%1,%0; trapb"
  42                            : "=f"(tmp) : "f"(HUGE_VAL));
  43     }
  44
  45   /* Next: division by zero.  */
  46   if (FE_DIVBYZERO & excepts)
  47     {
  48       __asm__ __volatile__("cmpteq $f31,$f31,%0; divt/sui %0,$f31,%0; trapb"
  49                            : "=f"(tmp));
  50     }
  51
  52   /* Next: overflow.  */
  53   if (FE_OVERFLOW & excepts)
  54     {
  55       __asm__ __volatile__("mult/sui %1,%1,%0; trapb"
  56                            : "=f"(tmp) : "f"(DBL_MAX));
  57     }
  58
  59   /* Next: underflow.  */
  60   if (FE_UNDERFLOW & excepts)
  61     {
  62       __asm__ __volatile__("divt/sui %1,%2,%0; trapb"
  63                            : "=f"(tmp) : "f"(DBL_MIN), "f"(16.0));
  64     }
  65
  66   /* Last: inexact.  */
  67   if (FE_INEXACT & excepts)
  68     {
  69       __asm__ __volatile__("divt/sui %1,%2,%0; trapb"
  70                            : "=f"(tmp) : "f"(1.0), "f"(M_PI));
  71     }
  72 }