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 1.3 2007/09/14 19:47:03 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.Pp 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.Pp 67.Bd -literal 68typedef enum { 69 FP_PS, /* 24 bit (single-precision) */ 70 FP_PRS, /* reserved */ 71 FP_PD, /* 53 bit (double-precision) */ 72 FP_PE /* 64 bit (extended-precision) */ 73} fp_prec_t; 74.Ed 75.Ft fp_prec_t 76.Fn fpgetprec void 77.Ft fp_prec_t 78.Fn fpsetprec "fp_prec_t precision" 79.Pp 80.Bd -literal 81#define fp_except_t int 82#define FP_X_INV 0x01 /* invalid operation */ 83#define FP_X_DNML 0x02 /* denormal */ 84#define FP_X_DZ 0x04 /* zero divide */ 85#define FP_X_OFL 0x08 /* overflow */ 86#define FP_X_UFL 0x10 /* underflow */ 87#define FP_X_IMP 0x20 /* (im)precision */ 88#define FP_X_STK 0x40 /* stack fault */ 89.Ed 90.Ft fp_except_t 91.Fn fpgetmask void 92.Ft fp_except_t 93.Fn fpsetmask "fp_except_t mask" 94.Ft fp_except_t 95.Fn fpgetsticky void 96.Ft fp_except_t 97.Fn fpresetsticky "fp_except_t sticky" 98.Sh DESCRIPTION 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 102occurs. These routines allow both setting the floating point exception 103masks, and resetting the exception sticky flags after an exception is 104detected. In addition, they allow setting the floating point rounding mode 105and precision. 106.Pp 107The 108.Fn fpgetround 109function 110returns the current floating point rounding mode. 111.Pp 112The 113.Fn fpsetround 114function 115sets the floating point rounding mode and returns 116the previous mode. 117.Pp 118The 119.Fn fpgetprec 120function 121returns the current floating point precision. 122.Pp 123The 124.Fn fpsetprec 125function 126sets the floating point precision and returns 127the previous precision. 128.Pp 129The 130.Fn fpgetmask 131function 132returns the current floating point exception masks. 133.Pp 134The 135.Fn fpsetmask 136function 137sets the floating point exception masks and returns the 138previous masks. 139.Pp 140The 141.Fn fpgetsticky 142function 143returns the current floating point sticky flags. 144.Pp 145The 146.Fn fpresetsticky 147function 148clears the floating point sticky flags and returns 149the previous flags. 150.Pp 151Sample code which prevents a trap on divide-by-zero: 152.Bd -literal -offset indent 153fpsetmask(~FP_X_DZ); 154a = 1.0; 155b = 0; 156c = a / b; 157fpresetsticky(FP_X_DZ); 158fpsetmask(FP_X_DZ); 159.Ed 160.Sh SEE ALSO 161.Xr isnan 3 162.Sh CAVEAT 163After a floating point exception and before a mask is set, the sticky 164flags must be reset. If another exception occurs before the sticky 165flags are reset, then a wrong exception type may be signaled. 166.Sh HISTORY 167These routines are based on SysV/386 routines of the same name. 168