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Diffstat (limited to 'share/man/man3/fpgetround.3')
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diff --git a/share/man/man3/fpgetround.3 b/share/man/man3/fpgetround.3 new file mode 100644 index 0000000..c6f01307 --- /dev/null +++ b/share/man/man3/fpgetround.3 @@ -0,0 +1,176 @@ +.\" Copyright (c) 1993 Andrew Moore, Talke Studio +.\" All rights reserved. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" 3. Neither the name of the University nor the names of its contributors +.\" may be used to endorse or promote products derived from this software +.\" without specific prior written permission. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND +.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE +.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS +.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY +.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +.\" SUCH DAMAGE. +.\" +.\" @(#)fpgetround.3 1.0 (Berkeley) 9/23/93 +.\" $FreeBSD$ +.\" +.Dd December 3, 2010 +.Dt FPGETROUND 3 +.Os +.Sh NAME +.Nm fpgetround , +.Nm fpsetround , +.Nm fpsetprec , +.Nm fpgetprec , +.Nm fpgetmask , +.Nm fpsetmask , +.Nm fpgetsticky , +.Nm fpresetsticky +.Nd IEEE floating point interface +.Sh SYNOPSIS +.In ieeefp.h +.Bd -literal +typedef enum { + FP_RN, /* round to nearest */ + FP_RM, /* round down to minus infinity */ + FP_RP, /* round up to plus infinity */ + FP_RZ /* truncate */ +} fp_rnd_t; +.Ed +.Ft fp_rnd_t +.Fn fpgetround void +.Ft fp_rnd_t +.Fn fpsetround "fp_rnd_t direction" +.Bd -literal +typedef enum { + FP_PS, /* 24 bit (single-precision) */ + FP_PRS, /* reserved */ + FP_PD, /* 53 bit (double-precision) */ + FP_PE /* 64 bit (extended-precision) */ +} fp_prec_t; +.Ed +.Ft fp_prec_t +.Fn fpgetprec void +.Ft fp_prec_t +.Fn fpsetprec "fp_prec_t precision" +.Bd -literal +#define fp_except_t int +#define FP_X_INV 0x01 /* invalid operation */ +#define FP_X_DNML 0x02 /* denormal */ +#define FP_X_DZ 0x04 /* zero divide */ +#define FP_X_OFL 0x08 /* overflow */ +#define FP_X_UFL 0x10 /* underflow */ +#define FP_X_IMP 0x20 /* (im)precision */ +#define FP_X_STK 0x40 /* stack fault */ +.Ed +.Ft fp_except_t +.Fn fpgetmask void +.Ft fp_except_t +.Fn fpsetmask "fp_except_t mask" +.Ft fp_except_t +.Fn fpgetsticky void +.Ft fp_except_t +.Fn fpresetsticky "fp_except_t sticky" +.Sh DESCRIPTION +The routines described herein are deprecated. +New code should use the functionality provided by +.Xr fenv 3 . +.Pp +When a floating point exception is detected, the exception sticky flag is +set and the exception mask is tested. +If the mask is set, then a trap +occurs. +These routines allow both setting the floating point exception +masks, and resetting the exception sticky flags after an exception is +detected. +In addition, they allow setting the floating point rounding mode +and precision. +.Pp +The +.Fn fpgetround +function +returns the current floating point rounding mode. +.Pp +The +.Fn fpsetround +function +sets the floating point rounding mode and returns +the previous mode. +.Pp +The +.Fn fpgetprec +function +returns the current floating point precision. +.Pp +The +.Fn fpsetprec +function +sets the floating point precision and returns +the previous precision. +.Pp +The +.Fn fpgetmask +function +returns the current floating point exception masks. +.Pp +The +.Fn fpsetmask +function +sets the floating point exception masks and returns the +previous masks. +.Pp +The +.Fn fpgetsticky +function +returns the current floating point sticky flags. +.Pp +The +.Fn fpresetsticky +function +clears the floating point sticky flags and returns +the previous flags. +.Pp +Sample code which prevents a trap on divide-by-zero: +.Bd -literal -offset indent +fpsetmask(~FP_X_DZ); +a = 1.0; +b = 0; +c = a / b; +fpresetsticky(FP_X_DZ); +fpsetmask(FP_X_DZ); +.Ed +.Sh IMPLEMENTATION NOTES +The +.Fn fpgetprec +and +.Fn fpsetprec +functions provide functionality unavailable on many platforms. +At present, they are implemented only on the i386 and amd64 platforms. +Changing precision is not a supported feature: +it may be ineffective when code is compiled to take advantage of SSE, +and many library functions and compiler optimizations depend upon the +default precision for correct behavior. +.Sh SEE ALSO +.Xr fenv 3 , +.Xr isnan 3 +.Sh HISTORY +These routines are based on SysV/386 routines of the same name. +.Sh CAVEATS +After a floating point exception and before a mask is set, the sticky +flags must be reset. +If another exception occurs before the sticky +flags are reset, then a wrong exception type may be signaled. |
