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 FECLEAREXCEPT 3 27.Os 28.Sh NAME 29.Nm feclearexcept , 30.Nm fegetexceptflag , 31.Nm feraiseexcept , 32.Nm fesetexceptflag , 33.Nm fetestexcept 34.Nd floating-point exception flag manipulation 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 feclearexcept "int excepts" 42.Ft int 43.Fn fegetexceptflag "fexcept_t *flagp" "int excepts" 44.Ft int 45.Fn feraiseexcept "int excepts" 46.Ft int 47.Fn fesetexceptflag "const fexcept_t *flagp" "int excepts" 48.Ft int 49.Fn fetestexcept "int excepts" 50.Sh DESCRIPTION 51The 52.Fn feclearexcept 53routine clears the floating-point exception flags specified by 54.Fa excepts , 55whereas 56.Fn feraiseexcept 57raises the specified exceptions. 58Raising an exception causes the corresponding flag to be set, 59and a 60.Dv SIGFPE 61is delivered to the process if the exception is unmasked. 62.Pp 63The 64.Fn fetestexcept 65function determines which flags are currently set, of those specified by 66.Fa excepts . 67.Pp 68The 69.Fn fegetexceptflag 70function stores the state of the exception flags specified in 71.Fa excepts 72in the opaque object pointed to by 73.Fa flagp . 74Similarly, 75.Fn fesetexceptflag 76changes the specified exception flags to reflect the state stored in 77the object pointed to by 78.Fa flagp . 79Note that the flags restored with 80.Fn fesetexceptflag 81must be a (not necessarily proper) subset of the flags recorded by 82a prior call to 83.Fn fegetexceptflag . 84.Pp 85For all of these functions, the possible types of exceptions 86include those described in 87.Xr fenv 3 . 88Some architectures may define other types of floating-point exceptions. 89.Sh IMPLEMENTATION NOTES 90On some architectures, raising an overflow or underflow exception 91also causes an inexact exception to be raised. 92In these cases, the overflow or underflow will be raised first. 93.Pp 94The 95.Fn fegetexceptflag 96and 97.Fn fesetexceptflag 98routines are preferred to 99.Fn fetestexcept 100and 101.Fn feraiseexcept , 102respectively, for saving and restoring exception flags. 103The latter do not re-raise exceptions and may preserve 104architecture-specific information such as addresses where 105exceptions occurred. 106.Sh RETURN VALUES 107The 108.Fn feclearexcept , 109.Fn fegetexceptflag , 110.Fn feraiseexcept , 111and 112.Fn fesetexceptflag 113functions return 0 upon success, and non-zero otherwise. 114The 115.Fn fetestexcept 116function returns the bitwise OR of the values of the current exception 117flags that were requested. 118.Sh SEE ALSO 119.Xr sigaction 2 , 120.Xr feholdexcept 3 , 121.Xr fenv 3 , 122.Xr feupdateenv 3 , 123.Xr fpgetsticky 3 , 124.Xr fpresetsticky 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 . 138