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 1.9.2.2 2001/12/17 11:30:11 ru Exp $ 34.\" $DragonFly: src/share/man/man3/fpgetround.3,v 1.4 2008/05/02 02:05:05 swildner Exp $ 35.\" 36.Dd August 23, 1993 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 fpresetsticky 48.Nd IEEE floating point interface 49.Sh LIBRARY 50.Lb libc 51.Sh SYNOPSIS 52.In ieeefp.h 53.Bd -literal 54typedef enum { 55 FP_RN, /* round to nearest */ 56 FP_RM, /* round down to minus infinity */ 57 FP_RP, /* round up to plus infinity */ 58 FP_RZ /* truncate */ 59} fp_rnd_t; 60.Ed 61.Ft fp_rnd_t 62.Fn fpgetround void 63.Ft fp_rnd_t 64.Fn fpsetround "fp_rnd_t direction" 65.Bd -literal 66typedef enum { 67 FP_PS, /* 24 bit (single-precision) */ 68 FP_PRS, /* reserved */ 69 FP_PD, /* 53 bit (double-precision) */ 70 FP_PE /* 64 bit (extended-precision) */ 71} fp_prec_t; 72.Ed 73.Ft fp_prec_t 74.Fn fpgetprec void 75.Ft fp_prec_t 76.Fn fpsetprec "fp_prec_t precision" 77.Bd -literal 78#define fp_except_t int 79#define FP_X_INV 0x01 /* invalid operation */ 80#define FP_X_DNML 0x02 /* denormal */ 81#define FP_X_DZ 0x04 /* zero divide */ 82#define FP_X_OFL 0x08 /* overflow */ 83#define FP_X_UFL 0x10 /* underflow */ 84#define FP_X_IMP 0x20 /* (im)precision */ 85#define FP_X_STK 0x40 /* stack fault */ 86.Ed 87.Ft fp_except_t 88.Fn fpgetmask void 89.Ft fp_except_t 90.Fn fpsetmask "fp_except_t mask" 91.Ft fp_except_t 92.Fn fpgetsticky void 93.Ft fp_except_t 94.Fn fpresetsticky "fp_except_t sticky" 95.Sh DESCRIPTION 96When a floating point exception is detected, the exception sticky flag is 97set and the exception mask is tested. 98If the mask is set, then a trap 99occurs. These routines allow both setting the floating point exception 100masks, and resetting the exception sticky flags after an exception is 101detected. In addition, they allow setting the floating point rounding mode 102and precision. 103.Pp 104The 105.Fn fpgetround 106function 107returns the current floating point rounding mode. 108.Pp 109The 110.Fn fpsetround 111function 112sets the floating point rounding mode and returns 113the previous mode. 114.Pp 115The 116.Fn fpgetprec 117function 118returns the current floating point precision. 119.Pp 120The 121.Fn fpsetprec 122function 123sets the floating point precision and returns 124the previous precision. 125.Pp 126The 127.Fn fpgetmask 128function 129returns the current floating point exception masks. 130.Pp 131The 132.Fn fpsetmask 133function 134sets the floating point exception masks and returns the 135previous masks. 136.Pp 137The 138.Fn fpgetsticky 139function 140returns the current floating point sticky flags. 141.Pp 142The 143.Fn fpresetsticky 144function 145clears the floating point sticky flags and returns 146the previous flags. 147.Pp 148Sample code which prevents a trap on divide-by-zero: 149.Bd -literal -offset indent 150fpsetmask(~FP_X_DZ); 151a = 1.0; 152b = 0; 153c = a / b; 154fpresetsticky(FP_X_DZ); 155fpsetmask(FP_X_DZ); 156.Ed 157.Sh SEE ALSO 158.Xr isnan 3 159.Sh CAVEAT 160After a floating point exception and before a mask is set, the sticky 161flags must be reset. If another exception occurs before the sticky 162flags are reset, then a wrong exception type may be signaled. 163.Sh HISTORY 164These routines are based on SysV/386 routines of the same name. 165