| .\" Copyright (c) 2004 David Schultz <das@FreeBSD.org> |
| .\" All rights reserved. |
| .\" |
| .\" Redistribution and use in source and binary forms, with or without |
| .\" modification, are permitted provided that the following conditions |
| .\" are met: |
| .\" 1. Redistributions of source code must retain the above copyright |
| .\" notice, this list of conditions and the following disclaimer. |
| .\" 2. Redistributions in binary form must reproduce the above copyright |
| .\" notice, this list of conditions and the following disclaimer in the |
| .\" documentation and/or other materials provided with the distribution. |
| .\" |
| .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND |
| .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| .\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE |
| .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| .\" SUCH DAMAGE. |
| .\" |
| .\" $FreeBSD: src/lib/msun/man/feenableexcept.3,v 1.1 2005/03/16 19:04:28 das Exp $ |
| .\" |
| .Dd March 16, 2005 |
| .Dt FEENABLEEXCEPT 3 |
| .Os |
| .Sh NAME |
| .Nm feenableexcept , |
| .Nm fedisableexcept , |
| .Nm fegetexcept |
| .Nd floating-point exception masking |
| .Sh LIBRARY |
| .Lb libm |
| .Sh SYNOPSIS |
| .In fenv.h |
| .Fd "#pragma STDC FENV_ACCESS ON" |
| .Ft int |
| .Fn feenableexcept "int excepts" |
| .Ft int |
| .Fn fedisableexcept "int excepts" |
| .Ft int |
| .Fn fegetexcept "void" |
| .Sh DESCRIPTION |
| The |
| .Fn feenableexcept |
| and |
| .Fn fedisableexcept |
| functions |
| unmask and mask (respectively) exceptions specified in |
| .Fa excepts . |
| The |
| .Fn fegetexcept |
| function |
| returns the current exception mask. |
| All exceptions are masked by default. |
| .Pp |
| Floating-point operations that produce unmasked exceptions will trap, and a |
| .Dv SIGFPE |
| will be delivered to the process. |
| By installing a signal handler for |
| .Dv SIGFPE , |
| applications can take appropriate action immediately without |
| testing the exception flags after every operation. |
| Note that the trap may not be immediate, but it should occur |
| before the next floating-point instruction is executed. |
| .Pp |
| For all of these functions, the possible types of exceptions |
| include those described in |
| .Xr fenv 3 . |
| Some architectures may define other types of floating-point exceptions. |
| .Sh RETURN VALUES |
| The |
| .Fn feenableexcept , |
| .Fn fedisableexcept , |
| and |
| .Fn fegetexcept |
| functions return a bitmap of the exceptions that were unmasked |
| prior to the call. |
| .Sh SEE ALSO |
| .Xr sigaction 2 , |
| .Xr feclearexcept 3 , |
| .Xr feholdexcept 3 , |
| .Xr fenv 3 , |
| .Xr feupdateenv 3 |
| .Sh BUGS |
| Functions in the standard library may trigger exceptions multiple |
| times as a result of intermediate computations; |
| however, they generally do not trigger spurious exceptions. |
| .Pp |
| No interface is provided to permit exceptions to be handled in |
| nontrivial ways. |
| There is no uniform way for an exception handler to access |
| information about the exception-causing instruction, or |
| to determine whether that instruction should be reexecuted |
| after returning from the handler. |