tests/test-fenv-except-trapping-1.c

   1 /* Test of turning floating-point exceptions into traps (signals).
   2    Copyright (C) 2023-2024 Free Software Foundation, Inc.
   3
   4    This program is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation, either version 3 of the License, or
   7    (at your option) any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  16
  17 /* Written by Bruno Haible <bruno@clisp.org>, 2023.  */
  18
  19 #include <config.h>
  20
  21 /* Specification.  */
  22 #include <fenv.h>
  23
  24 #include <stdio.h>
  25
  26 #include "macros.h"
  27
  28 /* Check of the Boole-an algebra.  */
  29
  30 /* Converts 5 bits to an exceptions bit mask.  */
  31 static int
  32 uint_to_exceptions (unsigned int a)
  33 {
  34   return (a & 0x01 ? FE_INVALID : 0)
  35          | (a & 0x02 ? FE_DIVBYZERO : 0)
  36          | (a & 0x04 ? FE_OVERFLOW : 0)
  37          | (a & 0x08 ? FE_UNDERFLOW : 0)
  38          | (a & 0x10 ? FE_INEXACT : 0);
  39 }
  40
  41 int
  42 main ()
  43 {
  44   unsigned int a, b;
  45
  46   /* Run through all possible valid arguments to feenableexcept and
  47      fedisableexcept.
  48      An alternative way of coding this iteration, without the uint_to_exceptions
  49      function, would be using the trick from
  50      Jörg Arndt: Matters Computational <https://www.jjj.de/fxt/fxtbook.pdf>
  51      § 1.25.1 Generating bit subsets of a given word  */
  52   for (a = 0; a < 0x20; a++)
  53     for (b = 0; b < 0x20; b++)
  54       {
  55         unsigned int c = a & ~b;
  56
  57         if (fedisableexcept (FE_ALL_EXCEPT) == -1
  58             || feenableexcept (uint_to_exceptions (a)) == -1)
  59           {
  60             if (test_exit_status != EXIT_SUCCESS)
  61               return test_exit_status;
  62             fputs ("Skipping test: trapping floating-point exceptions are not supported on this machine.\n", stderr);
  63             return 77;
  64           }
  65         ASSERT (fedisableexcept (uint_to_exceptions (b))
  66                 == uint_to_exceptions (a));
  67         /* Check fegetexcept.  */
  68         ASSERT (fegetexcept () == uint_to_exceptions (c));
  69         /* Check the return value of feenableexcept.  It should be consistent
  70            with fegetexcept.  */
  71         ASSERT (feenableexcept (0) == uint_to_exceptions (c));
  72       }
  73
  74   return test_exit_status;
  75 }