1  /* Copyright (C) 2013-2023 Free Software Foundation, Inc.
       2  
       3     This file is part of the GNU Atomic Library (libatomic).
       4  
       5     Libatomic is free software; you can redistribute it and/or modify it
       6     under the terms of the GNU General Public License as published by
       7     the Free Software Foundation; either version 3 of the License, or
       8     (at your option) any later version.
       9  
      10     Libatomic is distributed in the hope that it will be useful, but WITHOUT ANY
      11     WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
      12     FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
      13     more details.
      14  
      15     Under Section 7 of GPL version 3, you are granted additional
      16     permissions described in the GCC Runtime Library Exception, version
      17     3.1, as published by the Free Software Foundation.
      18  
      19     You should have received a copy of the GNU General Public License and
      20     a copy of the GCC Runtime Library Exception along with this program;
      21     see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
      22     <http://www.gnu.org/licenses/>.  */
      23  
      24  #include "libatomic_i.h"
      25  
      26  #define FE_INVALID	0x01
      27  #define FE_DENORM	0x02
      28  #define FE_DIVBYZERO	0x04
      29  #define FE_OVERFLOW	0x08
      30  #define FE_UNDERFLOW	0x10
      31  #define FE_INEXACT	0x20
      32  
      33  struct fenv
      34  {
      35    unsigned short int __control_word;
      36    unsigned short int __unused1;
      37    unsigned short int __status_word;
      38    unsigned short int __unused2;
      39    unsigned short int __tags;
      40    unsigned short int __unused3;
      41    unsigned int __eip;
      42    unsigned short int __cs_selector;
      43    unsigned int __opcode:11;
      44    unsigned int __unused4:5;
      45    unsigned int __data_offset;
      46    unsigned short int __data_selector;
      47    unsigned short int __unused5;
      48  } __attribute__ ((gcc_struct));
      49  
      50  #ifdef __SSE_MATH__
      51  # define __math_force_eval_div(x, y) \
      52    do { asm ("" : "+x" (x)); asm volatile ("" : : "x" (x / y)); } while (0)
      53  #else
      54  # define __math_force_eval_div(x, y) \
      55    do { asm ("" : "+t" (x)); asm volatile ("" : : "f" (x / y)); } while (0)
      56  #endif
      57  
      58  /* Raise the supported floating-point exceptions from EXCEPTS.  Other
      59     bits in EXCEPTS are ignored.  */
      60  
      61  void
      62  __atomic_feraiseexcept (int excepts)
      63  {
      64    struct fenv temp;
      65  
      66    if (excepts & FE_INVALID)
      67      {
      68        float f = 0.0f;
      69        __math_force_eval_div (f, f);
      70      }
      71    if (excepts & FE_DENORM)
      72      {
      73        asm volatile ("fnstenv\t%0" : "=m" (temp));
      74        temp.__status_word |= FE_DENORM;
      75        asm volatile ("fldenv\t%0" : : "m" (temp));
      76        asm volatile ("fwait");
      77      }
      78    if (excepts & FE_DIVBYZERO)
      79      {
      80        float f = 1.0f, g = 0.0f;
      81        __math_force_eval_div (f, g);
      82      }
      83    if (excepts & FE_OVERFLOW)
      84      {
      85        asm volatile ("fnstenv\t%0" : "=m" (temp));
      86        temp.__status_word |= FE_OVERFLOW;
      87        asm volatile ("fldenv\t%0" : : "m" (temp));
      88        asm volatile ("fwait");
      89      }
      90    if (excepts & FE_UNDERFLOW)
      91      {
      92        asm volatile ("fnstenv\t%0" : "=m" (temp));
      93        temp.__status_word |= FE_UNDERFLOW;
      94        asm volatile ("fldenv\t%0" : : "m" (temp));
      95        asm volatile ("fwait");
      96      }
      97    if (excepts & FE_INEXACT)
      98      {
      99        float f = 1.0f, g = 3.0f;
     100        __math_force_eval_div (f, g);
     101      }
     102  }