sysdeps/x86_64/fpu/fraiseexcpt.c

   1 /* Raise given exceptions.
   2    Copyright (C) 2001-2016 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, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <fenv.h>
  20 #include <math.h>
  21
  22 int
  23 __feraiseexcept (int excepts)
  24 {
  25   /* Raise exceptions represented by EXPECTS.  But we must raise only
  26      one signal at a time.  It is important that if the overflow/underflow
  27      exception and the inexact exception are given at the same time,
  28      the overflow/underflow exception follows the inexact exception.  */
  29
  30   /* First: invalid exception.  */
  31   if ((FE_INVALID & excepts) != 0)
  32     {
  33       /* One example of an invalid operation is 0.0 / 0.0.  */
  34       float f = 0.0;
  35
  36       __asm__ __volatile__ ("divss %0, %0 " : : "x" (f));
  37       (void) &f;
  38     }
  39
  40   /* Next: division by zero.  */
  41   if ((FE_DIVBYZERO & excepts) != 0)
  42     {
  43       float f = 1.0;
  44       float g = 0.0;
  45
  46       __asm__ __volatile__ ("divss %1, %0" : : "x" (f), "x" (g));
  47       (void) &f;
  48     }
  49
  50   /* Next: overflow.  */
  51   if ((FE_OVERFLOW & excepts) != 0)
  52     {
  53       /* XXX: Is it ok to only set the x87 FPU?  */
  54       /* There is no way to raise only the overflow flag.  Do it the
  55          hard way.  */
  56       fenv_t temp;
  57
  58       /* Bah, we have to clear selected exceptions.  Since there is no
  59          `fldsw' instruction we have to do it the hard way.  */
  60       __asm__ __volatile__ ("fnstenv %0" : "=m" (*&temp));
  61
  62       /* Set the relevant bits.  */
  63       temp.__status_word |= FE_OVERFLOW;
  64
  65       /* Put the new data in effect.  */
  66       __asm__ __volatile__ ("fldenv %0" : : "m" (*&temp));
  67
  68       /* And raise the exception.  */
  69       __asm__ __volatile__ ("fwait");
  70     }
  71
  72   /* Next: underflow.  */
  73   if ((FE_UNDERFLOW & excepts) != 0)
  74     {
  75       /* XXX: Is it ok to only set the x87 FPU?  */
  76       /* There is no way to raise only the underflow flag.  Do it the
  77          hard way.  */
  78       fenv_t temp;
  79
  80       /* Bah, we have to clear selected exceptions.  Since there is no
  81          `fldsw' instruction we have to do it the hard way.  */
  82       __asm__ __volatile__ ("fnstenv %0" : "=m" (*&temp));
  83
  84       /* Set the relevant bits.  */
  85       temp.__status_word |= FE_UNDERFLOW;
  86
  87       /* Put the new data in effect.  */
  88       __asm__ __volatile__ ("fldenv %0" : : "m" (*&temp));
  89
  90       /* And raise the exception.  */
  91       __asm__ __volatile__ ("fwait");
  92     }
  93
  94   /* Last: inexact.  */
  95   if ((FE_INEXACT & excepts) != 0)
  96     {
  97       /* XXX: Is it ok to only set the x87 FPU?  */
  98       /* There is no way to raise only the inexact flag.  Do it the
  99          hard way.  */
 100       fenv_t temp;
 101
 102       /* Bah, we have to clear selected exceptions.  Since there is no
 103          `fldsw' instruction we have to do it the hard way.  */
 104       __asm__ __volatile__ ("fnstenv %0" : "=m" (*&temp));
 105
 106       /* Set the relevant bits.  */
 107       temp.__status_word |= FE_INEXACT;
 108
 109       /* Put the new data in effect.  */
 110       __asm__ __volatile__ ("fldenv %0" : : "m" (*&temp));
 111
 112       /* And raise the exception.  */
 113       __asm__ __volatile__ ("fwait");
 114     }
 115
 116   /* Success.  */
 117   return 0;
 118 }
 119 libm_hidden_def (__feraiseexcept)
 120 weak_alias (__feraiseexcept, feraiseexcept)
 121 libm_hidden_weak (feraiseexcept)