sysdeps/i386/fpu/fraiseexcpt.c

   1 /* Raise given exceptions.
   2    Copyright (C) 1997-2020 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@cygnus.com>, 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 Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the 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    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <https://www.gnu.org/licenses/>.  */
  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 an invalid operation is 0.0 / 0.0.  */
  35       double d;
  36       __asm__ __volatile__ ("fldz; fdiv %%st, %%st(0); fwait" : "=t" (d));
  37       (void) &d;
  38     }
  39
  40   /* Next: division by zero.  */
  41   if ((FE_DIVBYZERO & excepts) != 0)
  42     {
  43       double d;
  44       __asm__ __volatile__ ("fldz; fld1; fdivp %%st, %%st(1); fwait"
  45                             : "=t" (d));
  46       (void) &d;
  47     }
  48
  49   /* Next: overflow.  */
  50   if ((FE_OVERFLOW & excepts) != 0)
  51     {
  52       /* There is no way to raise only the overflow flag.  Do it the
  53          hard way.  */
  54       fenv_t temp;
  55
  56       /* Bah, we have to clear selected exceptions.  Since there is no
  57          `fldsw' instruction we have to do it the hard way.  */
  58       __asm__ __volatile__ ("fnstenv %0" : "=m" (*&temp));
  59
  60       /* Set the relevant bits.  */
  61       temp.__status_word |= FE_OVERFLOW;
  62
  63       /* Put the new data in effect.  */
  64       __asm__ __volatile__ ("fldenv %0" : : "m" (*&temp));
  65
  66       /* And raise the exception.  */
  67       __asm__ __volatile__ ("fwait");
  68     }
  69
  70   /* Next: underflow.  */
  71   if ((FE_UNDERFLOW & excepts) != 0)
  72     {
  73       /* There is no way to raise only the underflow flag.  Do it the
  74          hard way.  */
  75       fenv_t temp;
  76
  77       /* Bah, we have to clear selected exceptions.  Since there is no
  78          `fldsw' instruction we have to do it the hard way.  */
  79       __asm__ __volatile__ ("fnstenv %0" : "=m" (*&temp));
  80
  81       /* Set the relevant bits.  */
  82       temp.__status_word |= FE_UNDERFLOW;
  83
  84       /* Put the new data in effect.  */
  85       __asm__ __volatile__ ("fldenv %0" : : "m" (*&temp));
  86
  87       /* And raise the exception.  */
  88       __asm__ __volatile__ ("fwait");
  89     }
  90
  91   /* Last: inexact.  */
  92   if ((FE_INEXACT & excepts) != 0)
  93     {
  94       /* There is no way to raise only the inexact flag.  Do it the
  95          hard way.  */
  96       fenv_t temp;
  97
  98       /* Bah, we have to clear selected exceptions.  Since there is no
  99          `fldsw' instruction we have to do it the hard way.  */
 100       __asm__ __volatile__ ("fnstenv %0" : "=m" (*&temp));
 101
 102       /* Set the relevant bits.  */
 103       temp.__status_word |= FE_INEXACT;
 104
 105       /* Put the new data in effect.  */
 106       __asm__ __volatile__ ("fldenv %0" : : "m" (*&temp));
 107
 108       /* And raise the exception.  */
 109       __asm__ __volatile__ ("fwait");
 110     }
 111
 112   /* Success.  */
 113   return 0;
 114 }
 115
 116 #include <shlib-compat.h>
 117 #if SHLIB_COMPAT (libm, GLIBC_2_1, GLIBC_2_2)
 118 strong_alias (__feraiseexcept, __old_feraiseexcept)
 119 compat_symbol (libm, __old_feraiseexcept, feraiseexcept, GLIBC_2_1);
 120 #endif
 121
 122 libm_hidden_def (__feraiseexcept)
 123 libm_hidden_ver (__feraiseexcept, feraiseexcept)
 124 versioned_symbol (libm, __feraiseexcept, feraiseexcept, GLIBC_2_2);