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.Dd May 8, 2004 26.Dt FEGETENV 3 27.Os 28.Sh NAME 29.Nm fegetenv , 30.Nm feholdexcept , 31.Nm fesetenv , 32.Nm feupdateenv 33.Nd floating-point environment save and restore 34.Sh LIBRARY 35.Lb libm 36.Sh SYNOPSIS 37.In fenv.h 38.Fd "#pragma STDC FENV_ACCESS ON" 39.Ft int 40.Fn fegetenv "fenv_t *envp" 41.Ft int 42.Fn feholdexcept "fenv_t *envp" 43.Ft int 44.Fn fesetenv "const fenv_t *envp" 45.Ft int 46.Fn feupdateenv "const fenv_t *envp" 47.Sh DESCRIPTION 48The floating-point environment includes exception flags and masks, the 49current rounding mode, and other architecture-specific settings. 50However, it does not include the floating-point register file. 51.Pp 52The 53.Fn fegetenv 54function stores the current floating-point environment in the object 55pointed to by 56.Fa envp , 57whereas 58.Fn feholdexcept 59saves the current environment, then clears all exception flags 60and masks all floating-point exceptions. 61.Pp 62The 63.Fn fesetenv 64function restores a previously saved environment. 65The 66.Fn feupdateenv 67function restores a saved environment as well, but it also 68raises any exceptions that were set in the environment it 69replaces. 70.Pp 71The 72.Fn feholdexcept 73function is often used with 74.Fn feupdateenv 75or 76.Fn fesetenv 77to suppress spurious exceptions that occur as a result of 78intermediate computations. 79An example in 80.Xr fenv 3 81demonstrates how to do this. 82.Sh RETURN VALUES 83The 84.Fn fegetenv , 85.Fn feholdexcept , 86.Fn fesetenv , 87and 88.Fn feupdateenv 89functions return 0 if they succeed, and non-zero otherwise. 90.Sh SEE ALSO 91.Xr feclearexcept 3 , 92.Xr fenv 3 , 93.Xr feraiseexcept 3 , 94.Xr fesetenv 3 , 95.Xr fetestexcept 3 , 96.Xr fpgetmask 3 , 97.Xr fpgetprec 3 , 98.Xr fpsetmask 3 , 99.Xr fpsetprec 3 100.Sh STANDARDS 101The 102.Fn fegetenv , 103.Fn feholdexcept , 104.Fn fesetenv , 105and 106.Fn feupdateenv 107functions conform to 108.St -isoC-99 . 109.Sh HISTORY 110These routines first appeared in 111.Fx 5.3 . 112