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. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)fpgetround.3 1.0 (Berkeley) 9/23/93 33.\" $FreeBSD: src/share/man/man3/fpgetround.3,v 1.15 2005/07/15 17:35:25 hrs Exp $ 34.\" $DragonFly: src/share/man/man3/fpgetround.3,v 1.4 2008/05/02 02:05:05 swildner Exp $ 35.\" 36.Dd April 23, 2009 37.Dt FPGETROUND 3 38.Os 39.Sh NAME 40.Nm fpgetround , 41.Nm fpsetround , 42.Nm fpsetprec , 43.Nm fpgetprec , 44.Nm fpgetmask , 45.Nm fpsetmask , 46.Nm fpgetsticky , 47.Nm fpsetsticky , 48.Nm fpresetsticky 49.Nd IEEE floating point interface 50.Sh LIBRARY 51.Lb libc 52.Sh SYNOPSIS 53.In ieeefp.h 54.Bd -literal 55typedef enum { 56 FP_RN, /* round to nearest */ 57 FP_RM, /* round down to minus infinity */ 58 FP_RP, /* round up to plus infinity */ 59 FP_RZ /* truncate */ 60} fp_rnd_t; 61.Ed 62.Ft fp_rnd_t 63.Fn fpgetround void 64.Ft fp_rnd_t 65.Fn fpsetround "fp_rnd_t direction" 66.Bd -literal 67typedef enum { 68 FP_PS, /* 24 bit (single-precision) */ 69 FP_PRS, /* reserved */ 70 FP_PD, /* 53 bit (double-precision) */ 71 FP_PE /* 64 bit (extended-precision) */ 72} fp_prec_t; 73.Ed 74.Ft fp_prec_t 75.Fn fpgetprec void 76.Ft fp_prec_t 77.Fn fpsetprec "fp_prec_t precision" 78.Bd -literal 79#define fp_except_t int 80#define FP_X_INV 0x01 /* invalid operation */ 81#define FP_X_DNML 0x02 /* denormal */ 82#define FP_X_DZ 0x04 /* zero divide */ 83#define FP_X_OFL 0x08 /* overflow */ 84#define FP_X_UFL 0x10 /* underflow */ 85#define FP_X_IMP 0x20 /* (im)precision */ 86#define FP_X_STK 0x40 /* stack fault */ 87.Ed 88.Ft fp_except_t 89.Fn fpgetmask void 90.Ft fp_except_t 91.Fn fpsetmask "fp_except_t mask" 92.Ft fp_except_t 93.Fn fpgetsticky void 94.Ft fp_except_t 95.Fn fpsetsticky "fp_except_t sticky" 96.Ft fp_except_t 97.Fn fpresetsticky "fp_except_t sticky" 98.Sh DESCRIPTION 99The routines described herein are deprecated. 100New code should use the functionality provided by 101.Xr fenv 3 . 102.Pp 103When a floating point exception is detected, the exception sticky flag is 104set and the exception mask is tested. 105If the mask is set, then a trap occurs. 106These routines allow both setting the floating point exception 107masks, and resetting the exception sticky flags after an exception is 108detected. 109In addition, they allow setting the floating point rounding mode 110and precision. 111.Pp 112The 113.Fn fpgetround 114function 115returns the current floating point rounding mode. 116.Pp 117The 118.Fn fpsetround 119function 120sets the floating point rounding mode and returns 121the previous mode. 122.Pp 123The 124.Fn fpgetprec 125function 126returns the current floating point precision. 127.Pp 128The 129.Fn fpsetprec 130function 131sets the floating point precision and returns 132the previous precision. 133.Pp 134The 135.Fn fpgetmask 136function 137returns the current floating point exception masks. 138.Pp 139The 140.Fn fpsetmask 141function 142sets the floating point exception masks and returns the 143previous masks. 144.Pp 145The 146.Fn fpgetsticky 147function 148returns the current floating point sticky flags. 149.Pp 150The 151.Fn fpsetsticky 152sets the floating point sticky flags and returns 153the previous flags. 154.Pp 155The 156.Fn fpresetsticky 157function 158clears the floating point sticky flags and returns 159the previous flags. 160.Pp 161Sample code which prevents a trap on divide-by-zero: 162.Bd -literal -offset indent 163fpsetmask(~FP_X_DZ); 164a = 1.0; 165b = 0; 166c = a / b; 167fpresetsticky(FP_X_DZ); 168fpsetmask(FP_X_DZ); 169.Ed 170.Sh IMPLEMENTATION NOTES 171The 172.Fn fpgetprec 173and 174.Fn fpsetprec 175functions provide functionality unavailable on many platforms. 176At present, they are implemented only on the i386 and x86_64 platforms. 177.Sh SEE ALSO 178.Xr fenv 3 , 179.Xr isnan 3 180.Sh CAVEATS 181After a floating point exception and before a mask is set, the sticky 182flags must be reset. 183If another exception occurs before the sticky 184flags are reset, then a wrong exception type may be signaled. 185.Sh HISTORY 186These routines are based on SysV/386 routines of the same name. 187