bf2cc57012
haven't existed for years, if they ever existed. The "prototypes" are actually for macros, so they are difficult to check automatically.
140 lines
4.3 KiB
Groff
140 lines
4.3 KiB
Groff
.\" Copyright (c) 1993 Andrew Moore, Talke Studio
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.\" All rights reserved.
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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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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)fpgetround.3 1.0 (Berkeley) 9/23/93
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.\" $Id: fpgetround.3,v 1.4 1997/03/19 20:42:18 bde Exp $
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.\"
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.Dd August 23, 1993
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.Dt FPGETROUND 3
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.Os
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.Sh NAME
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.Nm fpgetround ,
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.Nm fpsetround ,
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.Nm fpgetmask ,
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.Nm fpsetmask ,
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.Nm fpgetsticky ,
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.Nm fpresetsticky
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.Nd IEEE floating point interface
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.Sh SYNOPSIS
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.Fd #include <floatingpoint.h>
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.Ft typedef enum {
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.br
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.Fa FP_RN,
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.Li /* round to nearest */
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.br
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.Fa FP_RM,
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.Li /* round to minus infinity */
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.br
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.Fa FP_RP,
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.Li /* round to plus infinity */
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.br
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.Fa FP_RZ,
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.Li /* truncate */
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.br
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.Ft } fp_rnd_t;
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.Pp
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.Ft fp_rnd_t
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.Fn fpgetround void
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.Ft fp_rnd_t
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.Fn fpsetround "fp_rnd_t direction"
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.Fd #define fp_except_t int
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.Fd #define FP_X_INV 0x01 /* invalid */
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.Fd #define FP_X_OFL 0x08 /* overflow */
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.Fd #define FP_X_UFL 0x10 /* underflow */
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.Fd #define FP_X_DZ 0x04 /* divide-by-zero */
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.Fd #define FP_X_IMP 0x20 /* loss of precision */
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.Fd #define FP_X_DNML 0x02 /* denormal */
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.Ft fp_except_t
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.Fn fpgetmask 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_except_t
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.Fn fpgetsticky void
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.Ft fp_except_t
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.Fn fpresetsticky "fp_except_t sticky"
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.Sh DESCRIPTION
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When a floating point exception is detected, the exception sticky flag is
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set and the exception mask is tested. If the mask is set, then a trap
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occurs. These routines allow both setting the floating point exception
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masks, and resetting the exception sticky flags after an exception is
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detected. In addition, they allow setting the floating point rounding mode.
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.Pp
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The
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.Fn fpgetround
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function
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returns the current floating point rounding mode.
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.Pp
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The
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.Fn fpsetround
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function
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sets the floating point rounding mode and returns
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the previous mode.
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.Pp
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The
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.Fn fpgetmask
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function
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returns the current floating point exception masks.
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.Pp
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The
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.Fn fpsetmask
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function
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sets the floating point exception masks and returns the
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previous masks.
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.Pp
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The
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.Fn fpgetsticky
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function
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returns the current floating point sticky flags.
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.Pp
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The
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.Fn fpresetsticky
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function
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clears the floating point sticky flags and returns
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the previous flags.
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.Pp
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Sample code which prevents a trap on divide-by-zero:
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.Bd -literal -offset indent
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fpsetmask(~FP_X_DZ);
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a = 1.0;
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b = 0;
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c = a / b;
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fpresetsticky(FP_X_DZ);
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fpsetmask(FP_X_DZ);
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.Ed
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.Sh SEE ALSO
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.Xr isnan 3
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.Sh CAVEAT
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After a floating point exception and before a mask is set, the sticky
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flags must be reset. If another exception occurs before the sticky
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flags are reset, then a wrong exception type may be signaled.
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.Sh HISTORY
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These routines are based on SysV/386 routines of the same name.
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