1  /* Raise given exceptions.
       2     Copyright (C) 2000-2023 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_libc.h>
      20  #include <float.h>
      21  #include <math.h>
      22  
      23  
      24  static __inline__ void
      25  fexceptdiv (float d, float e)
      26  {
      27    __asm__ __volatile__ ("debr %0,%1" : : "f" (d), "f" (e) );
      28  }
      29  
      30  static __inline__ void
      31  fexceptadd (float d, float e)
      32  {
      33    __asm__ __volatile__ ("aebr %0,%1" : : "f" (d), "f" (e) );
      34  }
      35  
      36  #ifdef HAVE_S390_MIN_Z196_ZARCH_ASM_SUPPORT
      37  static __inline__ void
      38  fexceptround (double e)
      39  {
      40    float d;
      41    /* Load rounded from double to float with M3 = round toward 0, M4 = Suppress
      42       IEEE-inexact exception.
      43       In case of e=0x1p128 and the overflow-mask bit is zero, only the
      44       IEEE-overflow flag is set. If overflow-mask bit is one, DXC field is set to
      45       0x20 "IEEE overflow, exact".
      46       In case of e=0x1p-150 and the underflow-mask bit is zero, only the
      47       IEEE-underflow flag is set. If underflow-mask bit is one, DXC field is set
      48       to 0x10 "IEEE underflow, exact".
      49       This instruction is available with a zarch machine >= z196.  */
      50    __asm__ __volatile__ ("ledbra %0,5,%1,4" : "=f" (d) : "f" (e) );
      51  }
      52  #endif
      53  
      54  int
      55  __feraiseexcept (int excepts)
      56  {
      57    /* Raise exceptions represented by EXPECTS.  But we must raise only
      58       one signal at a time.  It is important that if the overflow/underflow
      59       exception and the inexact exception are given at the same time,
      60       the overflow/underflow exception follows the inexact exception.  */
      61  
      62    /* First: invalid exception.  */
      63    if (FE_INVALID & excepts)
      64      fexceptdiv (0.0, 0.0);
      65  
      66    /* Next: division by zero.  */
      67    if (FE_DIVBYZERO & excepts)
      68      fexceptdiv (1.0, 0.0);
      69  
      70    /* Next: overflow.  */
      71    if (FE_OVERFLOW & excepts)
      72      {
      73  #ifdef HAVE_S390_MIN_Z196_ZARCH_ASM_SUPPORT
      74        fexceptround (0x1p128);
      75  #else
      76        /* If overflow-mask bit is zero, both IEEE-overflow and IEEE-inexact flags
      77  	 are set.  If overflow-mask bit is one, DXC field is set to 0x2C "IEEE
      78  	 overflow, inexact and incremented".  */
      79        fexceptadd (FLT_MAX, 1.0e32);
      80  #endif
      81      }
      82  
      83    /* Next: underflow.  */
      84    if (FE_UNDERFLOW & excepts)
      85      {
      86  #ifdef HAVE_S390_MIN_Z196_ZARCH_ASM_SUPPORT
      87        fexceptround (0x1p-150);
      88  #else
      89        /* If underflow-mask bit is zero, both IEEE-underflow and IEEE-inexact
      90  	 flags are set.  If underflow-mask bit is one, DXC field is set to 0x1C
      91  	 "IEEE underflow, inexact and incremented".  */
      92        fexceptdiv (FLT_MIN, 3.0);
      93  #endif
      94      }
      95  
      96    /* Last: inexact.  */
      97    if (FE_INEXACT & excepts)
      98      fexceptdiv (2.0, 3.0);
      99  
     100    /* Success.  */
     101    return 0;
     102  }
     103  libm_hidden_def (__feraiseexcept)
     104  weak_alias (__feraiseexcept, feraiseexcept)
     105  libm_hidden_weak (feraiseexcept)