f14fb60209
* Updating common/lib * Updating lib/csu * Updating lib/libc * Updating libexec/ld.elf_so * Corrected test on __minix in featuretest to actually follow the meaning of the comment. * Cleaned up _REENTRANT-related defintions. * Disabled -D_REENTRANT for libfetch * Removing some unneeded __NBSD_LIBC defines and tests Change-Id: Ic1394baef74d11b9f86b312f5ff4bbc3cbf72ce2
173 lines
4.8 KiB
Groff
173 lines
4.8 KiB
Groff
.\" $NetBSD: fpgetmask.3,v 1.12 2011/03/27 22:55:07 wiz 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 March 26, 2011
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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 fpgetprec ,
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.Nm fpgetround ,
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.Nm fpgetsticky ,
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.Nm fpsetmask ,
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.Nm fpsetprec ,
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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_t
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.Fn fpgetmask void
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.Ft fp_prec_t
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.Fn fpgetprec void
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.Ft fp_rnd_t
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.Fn fpgetround void
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.Ft fp_except_t
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.Fn fpgetsticky void
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.Ft fp_except_t
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.Fn fpsetmask "fp_except_t mask"
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.Ft fp_prec_t
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.Fn fpsetprec "fp_prec_t prec"
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.Ft fp_rnd_t
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.Fn fpsetround "fp_rnd_t rnd_dir"
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.Ft fp_except_t
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.Fn fpsetsticky "fp_except_t sticky"
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.Sh DESCRIPTION
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A rounding mode
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.Ft fp_rnd_t
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is one of:
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.Bl -column -offset indent FP_RZ
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.It Dv FP_RZ Ta rounding towards Em zero
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.It Dv FP_RM Ta rounding down to Pq Em Minus infinity
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.It Dv FP_RN Ta rounding to Em nearest
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.It Dv FP_RP Ta rounding down to Pq Em Plus infinity
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.El
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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_t
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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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An
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.Ft fp_prec_t
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specifies the precision of the floating point operations listed below.
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.Bl -column -offset indent FP_RPS
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.It Dv FP_PS Ta Dv 24 bit (single-precision)
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.It Dv FP_PRS Ta reserved
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.It Dv FP_PD Ta Dv 53 bit (double-precision)
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.It Dv FP_PE Ta Dv 64 bit (extended-precision)
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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 fpgetprec
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function will return the current floating point precision.
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The
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.Fn fpsetprec
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function will set the floating point precision and will return
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the previous precision.
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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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.Xr fenv 3
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.Sh BUGS
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There is no way to return an unsupported value.
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Not all processors support all the modes.
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These interfaces are deprecated and the ones
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in
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.Xr fenv 3
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should be used, although the interfaces in
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.Xr fenv 3
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don't support getting or setting the precision.
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