sysdeps/x86_64/fpu/fraiseexcpt.c

   1 /* Raise given exceptions.
   2    Copyright (C) 2001, 2002 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <fenv.h>
  21 #include <math.h>
  22
  23 int
  24 feraiseexcept (int excepts)
  25 {
  26   /* Raise exceptions represented by EXPECTS.  But we must raise only
  27      one signal at a time.  It is important that if the overflow/underflow
  28      exception and the inexact exception are given at the same time,
  29      the overflow/underflow exception follows the inexact exception.  */
  30
  31   /* First: invalid exception.  */
  32   if ((FE_INVALID & excepts) != 0)
  33     {
  34       /* One example of a invalid operation is 0.0 / 0.0.  */
  35       float f = 0.0;
  36
  37       __asm__ __volatile__ ("divss %0, %0 " : : "x" (f));
  38       (void) &f;
  39     }
  40
  41   /* Next: division by zero.  */
  42   if ((FE_DIVBYZERO & excepts) != 0)
  43     {
  44       float f = 1.0;
  45       float g = 0.0;
  46
  47       __asm__ __volatile__ ("divss %1, %0" : : "x" (f), "x" (g));
  48       (void) &f;
  49     }
  50
  51   /* Next: overflow.  */
  52   if ((FE_OVERFLOW & excepts) != 0)
  53     {
  54       /* XXX: Is it ok to only set the x87 FPU?  */
  55       /* There is no way to raise only the overflow flag.  Do it the
  56          hard way.  */
  57       fenv_t temp;
  58
  59       /* Bah, we have to clear selected exceptions.  Since there is no
  60          `fldsw' instruction we have to do it the hard way.  */
  61       __asm__ __volatile__ ("fnstenv %0" : "=m" (*&temp));
  62
  63       /* Set the relevant bits.  */
  64       temp.__status_word |= FE_OVERFLOW;
  65
  66       /* Put the new data in effect.  */
  67       __asm__ __volatile__ ("fldenv %0" : : "m" (*&temp));
  68
  69       /* And raise the exception.  */
  70       __asm__ __volatile__ ("fwait");
  71     }
  72
  73   /* Next: underflow.  */
  74   if ((FE_UNDERFLOW & excepts) != 0)
  75     {
  76       /* XXX: Is it ok to only set the x87 FPU?  */
  77       /* There is no way to raise only the underflow flag.  Do it the
  78          hard way.  */
  79       fenv_t temp;
  80
  81       /* Bah, we have to clear selected exceptions.  Since there is no
  82          `fldsw' instruction we have to do it the hard way.  */
  83       __asm__ __volatile__ ("fnstenv %0" : "=m" (*&temp));
  84
  85       /* Set the relevant bits.  */
  86       temp.__status_word |= FE_UNDERFLOW;
  87
  88       /* Put the new data in effect.  */
  89       __asm__ __volatile__ ("fldenv %0" : : "m" (*&temp));
  90
  91       /* And raise the exception.  */
  92       __asm__ __volatile__ ("fwait");
  93     }
  94
  95   /* Last: inexact.  */
  96   if ((FE_INEXACT & excepts) != 0)
  97     {
  98       /* XXX: Is it ok to only set the x87 FPU?  */
  99       /* There is no way to raise only the inexact flag.  Do it the
 100          hard way.  */
 101       fenv_t temp;
 102
 103       /* Bah, we have to clear selected exceptions.  Since there is no
 104          `fldsw' instruction we have to do it the hard way.  */
 105       __asm__ __volatile__ ("fnstenv %0" : "=m" (*&temp));
 106
 107       /* Set the relevant bits.  */
 108       temp.__status_word |= FE_INEXACT;
 109
 110       /* Put the new data in effect.  */
 111       __asm__ __volatile__ ("fldenv %0" : : "m" (*&temp));
 112
 113       /* And raise the exception.  */
 114       __asm__ __volatile__ ("fwait");
 115     }
 116
 117   /* Success.  */
 118   return 0;
 119 }
 120 libm_hidden_def (feraiseexcept)