1  /* Raise given exceptions.
       2     Copyright (C) 1997-2023 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 <float.h>
      21  #include <math.h>
      22  #include <signal.h>
      23  #include <unistd.h>
      24  
      25  int
      26  __feraiseexcept (int excepts)
      27  {
      28    double tmp;
      29    double dummy;
      30  
      31    /* Raise exceptions represented by EXPECTS.  But we must raise only
      32       one signal at a time.  It is important the if the overflow/underflow
      33       exception and the inexact exception are given at the same time,
      34       the overflow/underflow exception precedes the inexact exception.  */
      35  
      36    /* We do these bits in assembly to be certain GCC doesn't optimize
      37       away something important.  */
      38  
      39    /* First: invalid exception.  */
      40    if (FE_INVALID & excepts)
      41      {
      42        /* One example of an invalid operation is 0 * Infinity.  */
      43        tmp = 0;
      44        __asm__ __volatile__ ("frcpa.s0 %0,p1=f0,f0" : "=f" (tmp) : : "p1" );
      45      }
      46  
      47    /* Next: division by zero.  */
      48    if (FE_DIVBYZERO & excepts)
      49      __asm__ __volatile__ ("frcpa.s0 %0,p1=f1,f0" : "=f" (tmp) : : "p1" );
      50  
      51    /* Next: overflow.  */
      52    if (FE_OVERFLOW & excepts)
      53      {
      54        dummy = DBL_MAX;
      55  
      56        __asm__ __volatile__ ("fadd.d.s0 %0=%1,%1" : "=f" (dummy) : "0" (dummy));
      57      }
      58  
      59    /* Next: underflow.  */
      60    if (FE_UNDERFLOW & excepts)
      61      {
      62        dummy = DBL_MIN;
      63  
      64        __asm__ __volatile__ ("fnma.d.s0 %0=%1,%1,f0" : "=f" (tmp) : "f" (dummy));
      65    }
      66  
      67    /* Last: inexact.  */
      68    if (FE_INEXACT & excepts)
      69      {
      70        dummy = DBL_MAX;
      71        __asm__ __volatile__ ("fsub.d.s0 %0=%1,f1" : "=f" (dummy) : "0" (dummy));
      72      }
      73  
      74    /* Success.  */
      75    return 0;
      76  }
      77  libm_hidden_def (__feraiseexcept)
      78  weak_alias (__feraiseexcept, feraiseexcept)
      79  libm_hidden_weak (feraiseexcept)