0dc9e0996a
As the current libc includes a libm implementation, with the new libc this is needed. Unneeded (for the moment) archs have been removed.
115 lines
3.2 KiB
Groff
115 lines
3.2 KiB
Groff
.\" $NetBSD: fegetenv.3,v 1.2 2010/08/04 18:58:18 wiz 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 May 8, 2004
|
|
.Dt FEGETENV 3
|
|
.Os
|
|
.Sh NAME
|
|
.Nm fegetenv ,
|
|
.Nm feholdexcept ,
|
|
.Nm fesetenv ,
|
|
.Nm feupdateenv
|
|
.Nd floating-point environment save and restore
|
|
.Sh LIBRARY
|
|
.Lb libm
|
|
.Sh SYNOPSIS
|
|
.In fenv.h
|
|
.Fd "#pragma STDC FENV_ACCESS ON"
|
|
.Ft int
|
|
.Fn fegetenv "fenv_t *envp"
|
|
.Ft int
|
|
.Fn feholdexcept "fenv_t *envp"
|
|
.Ft int
|
|
.Fn fesetenv "const fenv_t *envp"
|
|
.Ft int
|
|
.Fn feupdateenv "const fenv_t *envp"
|
|
.Sh DESCRIPTION
|
|
The floating-point environment includes exception flags and masks, the
|
|
current rounding mode, and other architecture-specific settings.
|
|
However, it does not include the floating-point register file.
|
|
.Pp
|
|
The
|
|
.Fn fegetenv
|
|
function stores the current floating-point environment in the object
|
|
pointed to by
|
|
.Fa envp ,
|
|
whereas
|
|
.Fn feholdexcept
|
|
saves the current environment, then clears all exception flags
|
|
and masks all floating-point exceptions.
|
|
.Pp
|
|
The
|
|
.Fn fesetenv
|
|
function restores a previously saved environment.
|
|
The
|
|
.Fn feupdateenv
|
|
function restores a saved environment as well, but it also
|
|
raises any exceptions that were set in the environment it
|
|
replaces.
|
|
.Pp
|
|
The
|
|
.Fn feholdexcept
|
|
function is often used with
|
|
.Fn feupdateenv
|
|
or
|
|
.Fn fesetenv
|
|
to suppress spurious exceptions that occur as a result of
|
|
intermediate computations.
|
|
An example in
|
|
.Xr fenv 3
|
|
demonstrates how to do this.
|
|
.Sh RETURN VALUES
|
|
The
|
|
.Fn fegetenv ,
|
|
.Fn feholdexcept ,
|
|
.Fn fesetenv ,
|
|
and
|
|
.Fn feupdateenv
|
|
functions return 0 if they succeed, and non-zero otherwise.
|
|
.Sh SEE ALSO
|
|
.Xr feclearexcept 3 ,
|
|
.Xr fenv 3 ,
|
|
.Xr feraiseexcept 3 ,
|
|
.Xr fesetenv 3 ,
|
|
.Xr fetestexcept 3 ,
|
|
.Xr fpgetmask 3 ,
|
|
.\"Xr fpgetprec 3 ,
|
|
.Xr fpsetmask 3
|
|
.\"Xr fpsetprec 3
|
|
.Sh STANDARDS
|
|
The
|
|
.Fn fegetenv ,
|
|
.Fn feholdexcept ,
|
|
.Fn fesetenv ,
|
|
and
|
|
.Fn feupdateenv
|
|
functions conform to
|
|
.St -isoC-99 .
|
|
.Sh HISTORY
|
|
These routines first appeared in
|
|
.Fx 5.3
|
|
and
|
|
.Nx 6.0 .
|