1.\" $NetBSD: feclearexcept.3,v 1.2 2010/08/07 18:13:12 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 FECLEAREXCEPT 3 28.Os 29.Sh NAME 30.Nm feclearexcept , 31.Nm fegetexceptflag , 32.Nm feraiseexcept , 33.Nm fesetexceptflag , 34.Nm fetestexcept 35.Nd floating-point exception flag manipulation 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 feclearexcept "int excepts" 43.Ft int 44.Fn fegetexceptflag "fexcept_t *flagp" "int excepts" 45.Ft int 46.Fn feraiseexcept "int excepts" 47.Ft int 48.Fn fesetexceptflag "const fexcept_t *flagp" "int excepts" 49.Ft int 50.Fn fetestexcept "int excepts" 51.Sh DESCRIPTION 52The 53.Fn feclearexcept 54routine clears the floating-point exception flags specified by 55.Fa excepts , 56whereas 57.Fn feraiseexcept 58raises the specified exceptions. 59Raising an exception causes the corresponding flag to be set, 60and a 61.Dv SIGFPE 62is delivered to the process if the exception is unmasked. 63.Pp 64The 65.Fn fetestexcept 66function determines which flags are currently set, of those specified by 67.Fa excepts . 68.Pp 69The 70.Fn fegetexceptflag 71function stores the state of the exception flags specified in 72.Fa excepts 73in the opaque object pointed to by 74.Fa flagp . 75Similarly, 76.Fn fesetexceptflag 77changes the specified exception flags to reflect the state stored in 78the object pointed to by 79.Fa flagp . 80Note that the flags restored with 81.Fn fesetexceptflag 82must be a (not necessarily proper) subset of the flags recorded by 83a prior call to 84.Fn fegetexceptflag . 85.Pp 86For all of these functions, the possible types of exceptions 87include those described in 88.Xr fenv 3 . 89Some architectures may define other types of floating-point exceptions. 90.Sh IMPLEMENTATION NOTES 91On some architectures, raising an overflow or underflow exception 92also causes an inexact exception to be raised. 93In these cases, the overflow or underflow will be raised first. 94.Pp 95The 96.Fn fegetexceptflag 97and 98.Fn fesetexceptflag 99routines are preferred to 100.Fn fetestexcept 101and 102.Fn feraiseexcept , 103respectively, for saving and restoring exception flags. 104The latter do not re-raise exceptions and may preserve 105architecture-specific information such as addresses where 106exceptions occurred. 107.Sh RETURN VALUES 108The 109.Fn feclearexcept , 110.Fn fegetexceptflag , 111.Fn feraiseexcept , 112and 113.Fn fesetexceptflag 114functions return 0 upon success, and non-zero otherwise. 115The 116.Fn fetestexcept 117function returns the bitwise OR of the values of the current exception 118flags that were requested. 119.Sh SEE ALSO 120.Xr sigaction 2 , 121.Xr feholdexcept 3 , 122.Xr fenv 3 , 123.Xr feupdateenv 3 , 124.Xr fpgetsticky 3 125.Sh STANDARDS 126The 127.Fn feclearexcept , 128.Fn fegetexceptflag , 129.Fn feraiseexcept , 130.Fn fesetexceptflag , 131and 132.Fn fetestexcept 133routines conform to 134.St -isoC-99 . 135.Sh HISTORY 136These functions first appeared in 137.Fx 5.3 138and 139.Nx 6.0 . 140