.\"	$NetBSD: fpgetmask.3,v 1.6 2002/10/01 16:48:34 wiz Exp $
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.\" Copyright (c) 1999 The NetBSD Foundation, Inc.
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.\" by Ross Harvey.
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.Dd April 29, 1999
.Dt FPGETMASK 3
.Os
.Sh NAME
.Nm fpgetmask ,
.Nm fpgetround ,
.Nm fpgetsticky ,
.Nm fpsetmask ,
.Nm fpsetround ,
.Nm fpsetsticky
.Nd IEEE FP mode control
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.Fd #include \*[Lt]ieeefp.h\*[Gt]
.Ft fp_except
.Fn fpgetmask void
.Ft fp_rnd
.Fn fpgetround void
.Ft fp_except
.Fn fpgetsticky void
.Ft fp_except
.Fn fpsetmask fp_except\ mask
.Ft fp_rnd
.Fn fpsetround fp_rnd\ rnd_dir
.Ft fp_except
.Fn fpsetsticky fp_except\ sticky
.Sh DESCRIPTION
A rounding mode is one of
.Dv FP_RZ , FP_RM , FP_RN ,
or
.Dv FP_RP ,
for rounding towards zero, rounding
.Pq Em Minus infinity
down, rounding to
.Em nearest ,
and rounding
.Pq Em Plus infinity
up.
The default mode is
.Dv FP_RN .
.Pp
An
.Ft fp_except
value is a bitmask specifying an exception type and containing any of
the values listed below.
.Bl -column -offset indent FP_X_UFLxx
.It Dv FP_X_INV Ta Invalid\ Operation
.It Dv FP_X_DZ Ta Division\ by\ zero
.It Dv FP_X_OFL Ta Overflow
.It Dv FP_X_UFL Ta Underflow
.It Dv FP_X_IMP Ta Imprecision (inexact)
.It Dv FP_X_IOV Ta Integer\ Overflow
.El
.Pp
The
.Fn fpsetmask
function will cause future operations with the specified result status to
raise the
.Dv SIGFPE
exception.
The
.Fn fpsetround
function will cause future operations to use the specified dynamic mode.
.Bl -tag -width Note:x
.It Em Note :
On some architectures, instructions can optionally specify static
rounding modes and exception enables that will supersede the specified
dynamic mode.
On other architectures, these features may not be fully supported.
.El
.Pp
The
.Fn fpsetsticky
function will set or clear the specified exception history bits.
.Sh RETURN VALUES
The
.Fn fpgetround
and
.Fn fpsetround
functions return the
.Pq previous
rounding mode.
The
.Fn fpgetmask ,
.Fn fpsetmask ,
.Fn fpgetsticky ,
and
.Fn fpsetsticky
functions return the
.Pq previous
exception mask and exception history bits.
.Sh SEE ALSO
.Xr sigaction 2