1.\" Copyright (c) 1993 Andrew Moore, Talke Studio 2.\" All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" @(#)fpgetround.3 1.0 (Berkeley) 9/23/93 29.\" $FreeBSD: src/share/man/man3/fpgetround.3,v 1.15 2005/07/15 17:35:25 hrs Exp $ 30.\" $DragonFly: src/share/man/man3/fpgetround.3,v 1.4 2008/05/02 02:05:05 swildner Exp $ 31.\" 32.Dd April 23, 2009 33.Dt FPGETROUND 3 34.Os 35.Sh NAME 36.Nm fpgetround , 37.Nm fpsetround , 38.Nm fpsetprec , 39.Nm fpgetprec , 40.Nm fpgetmask , 41.Nm fpsetmask , 42.Nm fpgetsticky , 43.Nm fpsetsticky , 44.Nm fpresetsticky 45.Nd IEEE floating point interface 46.Sh LIBRARY 47.Lb libc 48.Sh SYNOPSIS 49.In ieeefp.h 50.Bd -literal 51typedef enum { 52 FP_RN, /* round to nearest */ 53 FP_RM, /* round down to minus infinity */ 54 FP_RP, /* round up to plus infinity */ 55 FP_RZ /* truncate */ 56} fp_rnd_t; 57.Ed 58.Ft fp_rnd_t 59.Fn fpgetround void 60.Ft fp_rnd_t 61.Fn fpsetround "fp_rnd_t direction" 62.Bd -literal 63typedef enum { 64 FP_PS, /* 24 bit (single-precision) */ 65 FP_PRS, /* reserved */ 66 FP_PD, /* 53 bit (double-precision) */ 67 FP_PE /* 64 bit (extended-precision) */ 68} fp_prec_t; 69.Ed 70.Ft fp_prec_t 71.Fn fpgetprec void 72.Ft fp_prec_t 73.Fn fpsetprec "fp_prec_t precision" 74.Bd -literal 75#define fp_except_t int 76#define FP_X_INV 0x01 /* invalid operation */ 77#define FP_X_DNML 0x02 /* denormal */ 78#define FP_X_DZ 0x04 /* zero divide */ 79#define FP_X_OFL 0x08 /* overflow */ 80#define FP_X_UFL 0x10 /* underflow */ 81#define FP_X_IMP 0x20 /* (im)precision */ 82#define FP_X_STK 0x40 /* stack fault */ 83.Ed 84.Ft fp_except_t 85.Fn fpgetmask void 86.Ft fp_except_t 87.Fn fpsetmask "fp_except_t mask" 88.Ft fp_except_t 89.Fn fpgetsticky void 90.Ft fp_except_t 91.Fn fpsetsticky "fp_except_t sticky" 92.Ft fp_except_t 93.Fn fpresetsticky "fp_except_t sticky" 94.Sh DESCRIPTION 95The routines described herein are deprecated. 96New code should use the functionality provided by 97.Xr fenv 3 . 98.Pp 99When a floating point exception is detected, the exception sticky flag is 100set and the exception mask is tested. 101If the mask is set, then a trap occurs. 102These routines allow both setting the floating point exception 103masks, and resetting the exception sticky flags after an exception is 104detected. 105In addition, they allow setting the floating point rounding mode 106and precision. 107.Pp 108The 109.Fn fpgetround 110function 111returns the current floating point rounding mode. 112.Pp 113The 114.Fn fpsetround 115function 116sets the floating point rounding mode and returns 117the previous mode. 118.Pp 119The 120.Fn fpgetprec 121function 122returns the current floating point precision. 123.Pp 124The 125.Fn fpsetprec 126function 127sets the floating point precision and returns 128the previous precision. 129.Pp 130The 131.Fn fpgetmask 132function 133returns the current floating point exception masks. 134.Pp 135The 136.Fn fpsetmask 137function 138sets the floating point exception masks and returns the 139previous masks. 140.Pp 141The 142.Fn fpgetsticky 143function 144returns the current floating point sticky flags. 145.Pp 146The 147.Fn fpsetsticky 148sets the floating point sticky flags and returns 149the previous flags. 150.Pp 151The 152.Fn fpresetsticky 153function 154clears the floating point sticky flags and returns 155the previous flags. 156.Pp 157Sample code which prevents a trap on divide-by-zero: 158.Bd -literal -offset indent 159fpsetmask(~FP_X_DZ); 160a = 1.0; 161b = 0; 162c = a / b; 163fpresetsticky(FP_X_DZ); 164fpsetmask(FP_X_DZ); 165.Ed 166.Sh IMPLEMENTATION NOTES 167The 168.Fn fpgetprec 169and 170.Fn fpsetprec 171functions provide functionality unavailable on many platforms. 172At present, they are implemented only on the i386 and x86_64 platforms. 173.Sh SEE ALSO 174.Xr fenv 3 , 175.Xr isnan 3 176.Sh CAVEATS 177After a floating point exception and before a mask is set, the sticky 178flags must be reset. 179If another exception occurs before the sticky 180flags are reset, then a wrong exception type may be signaled. 181.Sh HISTORY 182These routines are based on SysV/386 routines of the same name. 183