1.\" $NetBSD: fegetenv.3,v 1.2 2010/08/04 18:58:18 wiz Exp $ 2.\" Copyright (c) 2004 David Schultz <das@FreeBSD.org> 3.\" All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 14.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24.\" SUCH DAMAGE. 25.\" 26.Dd May 8, 2004 27.Dt FEGETENV 3 28.Os 29.Sh NAME 30.Nm fegetenv , 31.Nm feholdexcept , 32.Nm fesetenv , 33.Nm feupdateenv 34.Nd floating-point environment save and restore 35.Sh LIBRARY 36.Lb libm 37.Sh SYNOPSIS 38.In fenv.h 39.Fd "#pragma STDC FENV_ACCESS ON" 40.Ft int 41.Fn fegetenv "fenv_t *envp" 42.Ft int 43.Fn feholdexcept "fenv_t *envp" 44.Ft int 45.Fn fesetenv "const fenv_t *envp" 46.Ft int 47.Fn feupdateenv "const fenv_t *envp" 48.Sh DESCRIPTION 49The floating-point environment includes exception flags and masks, the 50current rounding mode, and other architecture-specific settings. 51However, it does not include the floating-point register file. 52.Pp 53The 54.Fn fegetenv 55function stores the current floating-point environment in the object 56pointed to by 57.Fa envp , 58whereas 59.Fn feholdexcept 60saves the current environment, then clears all exception flags 61and masks all floating-point exceptions. 62.Pp 63The 64.Fn fesetenv 65function restores a previously saved environment. 66The 67.Fn feupdateenv 68function restores a saved environment as well, but it also 69raises any exceptions that were set in the environment it 70replaces. 71.Pp 72The 73.Fn feholdexcept 74function is often used with 75.Fn feupdateenv 76or 77.Fn fesetenv 78to suppress spurious exceptions that occur as a result of 79intermediate computations. 80An example in 81.Xr fenv 3 82demonstrates how to do this. 83.Sh RETURN VALUES 84The 85.Fn fegetenv , 86.Fn feholdexcept , 87.Fn fesetenv , 88and 89.Fn feupdateenv 90functions return 0 if they succeed, and non-zero otherwise. 91.Sh SEE ALSO 92.Xr feclearexcept 3 , 93.Xr fenv 3 , 94.Xr feraiseexcept 3 , 95.Xr fesetenv 3 , 96.Xr fetestexcept 3 , 97.Xr fpgetmask 3 , 98.\"Xr fpgetprec 3 , 99.Xr fpsetmask 3 100.\"Xr fpsetprec 3 101.Sh STANDARDS 102The 103.Fn fegetenv , 104.Fn feholdexcept , 105.Fn fesetenv , 106and 107.Fn feupdateenv 108functions conform to 109.St -isoC-99 . 110.Sh HISTORY 111These routines first appeared in 112.Fx 5.3 113and 114.Nx 6.0 . 115