sysdeps/i386/fpu/fraiseexcpt.c

   1 /* Raise given exceptions.
   2    Copyright (C) 1997-2022 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    <https://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       double d;
  35       __asm__ __volatile__ ("fldz; fdiv %%st, %%st(0); fwait" : "=t" (d));
  36       (void) &d;
  37     }
  38
  39   /* Next: division by zero.  */
  40   if ((FE_DIVBYZERO & excepts) != 0)
  41     {
  42       double d;
  43       __asm__ __volatile__ ("fldz; fld1; fdivp %%st, %%st(1); fwait"
  44                             : "=t" (d));
  45       (void) &d;
  46     }
  47
  48   /* Next: overflow.  */
  49   if ((FE_OVERFLOW & excepts) != 0)
  50     {
  51       /* There is no way to raise only the overflow flag.  Do it the
  52          hard way.  */
  53       fenv_t temp;
  54
  55       /* Bah, we have to clear selected exceptions.  Since there is no
  56          `fldsw' instruction we have to do it the hard way.  */
  57       __asm__ __volatile__ ("fnstenv %0" : "=m" (*&temp));
  58
  59       /* Set the relevant bits.  */
  60       temp.__status_word |= FE_OVERFLOW;
  61
  62       /* Put the new data in effect.  */
  63       __asm__ __volatile__ ("fldenv %0" : : "m" (*&temp));
  64
  65       /* And raise the exception.  */
  66       __asm__ __volatile__ ("fwait");
  67     }
  68
  69   /* Next: underflow.  */
  70   if ((FE_UNDERFLOW & excepts) != 0)
  71     {
  72       /* There is no way to raise only the underflow flag.  Do it the
  73          hard way.  */
  74       fenv_t temp;
  75
  76       /* Bah, we have to clear selected exceptions.  Since there is no
  77          `fldsw' instruction we have to do it the hard way.  */
  78       __asm__ __volatile__ ("fnstenv %0" : "=m" (*&temp));
  79
  80       /* Set the relevant bits.  */
  81       temp.__status_word |= FE_UNDERFLOW;
  82
  83       /* Put the new data in effect.  */
  84       __asm__ __volatile__ ("fldenv %0" : : "m" (*&temp));
  85
  86       /* And raise the exception.  */
  87       __asm__ __volatile__ ("fwait");
  88     }
  89
  90   /* Last: inexact.  */
  91   if ((FE_INEXACT & excepts) != 0)
  92     {
  93       /* There is no way to raise only the inexact flag.  Do it the
  94          hard way.  */
  95       fenv_t temp;
  96
  97       /* Bah, we have to clear selected exceptions.  Since there is no
  98          `fldsw' instruction we have to do it the hard way.  */
  99       __asm__ __volatile__ ("fnstenv %0" : "=m" (*&temp));
 100
 101       /* Set the relevant bits.  */
 102       temp.__status_word |= FE_INEXACT;
 103
 104       /* Put the new data in effect.  */
 105       __asm__ __volatile__ ("fldenv %0" : : "m" (*&temp));
 106
 107       /* And raise the exception.  */
 108       __asm__ __volatile__ ("fwait");
 109     }
 110
 111   /* Success.  */
 112   return 0;
 113 }
 114
 115 #include <shlib-compat.h>
 116 #if SHLIB_COMPAT (libm, GLIBC_2_1, GLIBC_2_2)
 117 strong_alias (__feraiseexcept, __old_feraiseexcept)
 118 compat_symbol (libm, __old_feraiseexcept, feraiseexcept, GLIBC_2_1);
 119 #endif
 120
 121 libm_hidden_def (__feraiseexcept)
 122 libm_hidden_ver (__feraiseexcept, feraiseexcept)
 123 versioned_symbol (libm, __feraiseexcept, feraiseexcept, GLIBC_2_2);