b6cbf7203b
This patch imports the unmodified current version of NetBSD libc. The NetBSD includes are in /nbsd_include, while the libc code itself is split between lib/nbsd_libc and common/lib/libc.
141 lines
3.8 KiB
Groff
141 lines
3.8 KiB
Groff
.\" $NetBSD: fpgetmask.3,v 1.10 2008/04/30 13:10:50 martin Exp $
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.\"
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.\" Copyright (c) 1999 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed to The NetBSD Foundation
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.\" by Ross Harvey.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd April 4, 2004
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.Dt FPGETMASK 3
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.Os
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.Sh NAME
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.Nm fpgetmask ,
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.Nm fpgetround ,
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.Nm fpgetsticky ,
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.Nm fpsetmask ,
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.Nm fpsetround ,
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.Nm fpsetsticky
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.Nd IEEE FP mode control
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In ieeefp.h
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.Ft fp_except
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.Fn fpgetmask void
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.Ft fp_rnd
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.Fn fpgetround void
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.Ft fp_except
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.Fn fpgetsticky void
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.Ft fp_except
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.Fn fpsetmask fp_except\ mask
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.Ft fp_rnd
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.Fn fpsetround fp_rnd\ rnd_dir
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.Ft fp_except
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.Fn fpsetsticky fp_except\ sticky
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.Sh DESCRIPTION
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A rounding mode is one of
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.Dv FP_RZ , FP_RM , FP_RN ,
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or
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.Dv FP_RP ,
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for rounding towards zero, rounding
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.Pq Em Minus infinity
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down, rounding to
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.Em nearest ,
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and rounding
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.Pq Em Plus infinity
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up.
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The default mode is
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.Dv FP_RN .
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.Pp
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An
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.Ft fp_except
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value is a bitmask specifying an exception type and containing any of
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the values listed below.
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.Bl -column -offset indent FP_X_UFLxx
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.It Dv FP_X_INV Ta Invalid\ Operation
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.It Dv FP_X_DZ Ta Division\ by\ zero
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.It Dv FP_X_OFL Ta Overflow
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.It Dv FP_X_UFL Ta Underflow
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.It Dv FP_X_IMP Ta Imprecision (inexact)
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.It Dv FP_X_IOV Ta Integer\ Overflow
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.El
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.Pp
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The
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.Fn fpsetmask
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function will set the current exception mask, i.e., it will cause
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future operations with the specified result status to raise the
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.Dv SIGFPE
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exception.
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The
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.Fn fpgetmask
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function will return the current exception mask.
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.Pp
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The
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.Fn fpsetround
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function will cause future operations to use the specified dynamic
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rounding mode.
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The
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.Fn fpgetround
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function will return the current rounding mode.
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.Bl -tag -width Note:x
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.It Em Note :
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On some architectures, instructions can optionally specify static
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rounding modes and exception enables that will supersede the specified
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dynamic mode.
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On other architectures, these features may not be fully supported.
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.El
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.Pp
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A
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.Dq sticky
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status word may be maintained in which a bit is set every time an
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exceptional floating point condition is encountered, whether or not a
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.Dv SIGFPE
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is generated.
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The
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.Fn fpsetsticky
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function will set or clear the specified exception history bits.
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The
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.Fn fpgetsticky
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function will return the exception history bits.
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.Sh RETURN VALUES
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The
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.Fn fpgetround
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and
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.Fn fpsetround
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functions return the
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.Pq previous
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rounding mode.
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The
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.Fn fpgetmask ,
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.Fn fpsetmask ,
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.Fn fpgetsticky ,
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and
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.Fn fpsetsticky
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functions return the
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.Pq previous
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exception mask and exception history bits.
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.Sh SEE ALSO
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.Xr sigaction 2
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