| .\" Copyright (c) 2004 David Schultz <das@FreeBSD.org> |
| .\" All rights reserved. |
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| .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND |
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| .\" $FreeBSD: src/lib/msun/man/feclearexcept.3,v 1.3 2005/01/14 09:12:05 ru Exp $ |
| .\" |
| .Dd May 8, 2004 |
| .Dt FECLEAREXCEPT 3 |
| .Os |
| .Sh NAME |
| .Nm feclearexcept , |
| .Nm fegetexceptflag , |
| .Nm feraiseexcept , |
| .Nm fesetexceptflag , |
| .Nm fetestexcept |
| .Nd floating-point exception flag manipulation |
| .Sh LIBRARY |
| .Lb libm |
| .Sh SYNOPSIS |
| .In fenv.h |
| .Fd "#pragma STDC FENV_ACCESS ON" |
| .Ft int |
| .Fn feclearexcept "int excepts" |
| .Ft int |
| .Fn fegetexceptflag "fexcept_t *flagp" "int excepts" |
| .Ft int |
| .Fn feraiseexcept "int excepts" |
| .Ft int |
| .Fn fesetexceptflag "const fexcept_t *flagp" "int excepts" |
| .Ft int |
| .Fn fetestexcept "int excepts" |
| .Sh DESCRIPTION |
| The |
| .Fn feclearexcept |
| routine clears the floating-point exception flags specified by |
| .Fa excepts , |
| whereas |
| .Fn feraiseexcept |
| raises the specified exceptions. |
| Raising an exception causes the corresponding flag to be set, |
| and a |
| .Dv SIGFPE |
| is delivered to the process if the exception is unmasked. |
| .Pp |
| The |
| .Fn fetestexcept |
| function determines which flags are currently set, of those specified by |
| .Fa excepts . |
| .Pp |
| The |
| .Fn fegetexceptflag |
| function stores the state of the exception flags specified in |
| .Fa excepts |
| in the opaque object pointed to by |
| .Fa flagp . |
| Similarly, |
| .Fn fesetexceptflag |
| changes the specified exception flags to reflect the state stored in |
| the object pointed to by |
| .Fa flagp . |
| Note that the flags restored with |
| .Fn fesetexceptflag |
| must be a (not necessarily proper) subset of the flags recorded by |
| a prior call to |
| .Fn fegetexceptflag . |
| .Pp |
| For all of these functions, the possible types of exceptions |
| include those described in |
| .Xr fenv 3 . |
| Some architectures may define other types of floating-point exceptions. |
| .Sh IMPLEMENTATION NOTES |
| On some architectures, raising an overflow or underflow exception |
| also causes an inexact exception to be raised. |
| In these cases, the overflow or underflow will be raised first. |
| .Pp |
| The |
| .Fn fegetexceptflag |
| and |
| .Fn fesetexceptflag |
| routines are preferred to |
| .Fn fetestexcept |
| and |
| .Fn feraiseexcept , |
| respectively, for saving and restoring exception flags. |
| The latter do not re-raise exceptions and may preserve |
| architecture-specific information such as addresses where |
| exceptions occurred. |
| .Sh RETURN VALUES |
| The |
| .Fn feclearexcept , |
| .Fn fegetexceptflag , |
| .Fn feraiseexcept , |
| and |
| .Fn fesetexceptflag |
| functions return 0 upon success, and non-zero otherwise. |
| The |
| .Fn fetestexcept |
| function returns the bitwise OR of the values of the current exception |
| flags that were requested. |
| .Sh SEE ALSO |
| .Xr sigaction 2 , |
| .Xr feholdexcept 3 , |
| .Xr fenv 3 , |
| .Xr feupdateenv 3 , |
| .Xr fpgetsticky 3 , |
| .Xr fpresetsticky 3 |
| .Sh STANDARDS |
| The |
| .Fn feclearexcept , |
| .Fn fegetexceptflag , |
| .Fn feraiseexcept , |
| .Fn fesetexceptflag , |
| and |
| .Fn fetestexcept |
| routines conform to |
| .St -isoC-99 . |
| .Sh HISTORY |
| These functions first appeared in |
| .Fx 5.3 . |