98 lines
3.3 KiB
Groff
98 lines
3.3 KiB
Groff
|
.\" $NetBSD: feenableexcept.3,v 1.1 2010/07/31 21:47:53 joerg Exp $
|
||
|
|
.\" 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.
|
||
|
|
.\"
|
||
|
|
.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.
|