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