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 1.2 2003/06/17 04:36:58 dillon 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 SYNOPSIS 50.In ieeefp.h 51.Pp 52.Bd -literal 53typedef enum { 54 FP_RN, /* round to nearest */ 55 FP_RM, /* round down to minus infinity */ 56 FP_RP, /* round up to plus infinity */ 57 FP_RZ /* truncate */ 58} fp_rnd_t; 59.Ed 60.Ft fp_rnd_t 61.Fn fpgetround void 62.Ft fp_rnd_t 63.Fn fpsetround "fp_rnd_t direction" 64.Pp 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.Pp 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 fpresetsticky "fp_except_t sticky" 96.Sh DESCRIPTION 97When a floating point exception is detected, the exception sticky flag is 98set and the exception mask is tested. 99If the mask is set, then a trap 100occurs. These routines allow both setting the floating point exception 101masks, and resetting the exception sticky flags after an exception is 102detected. In addition, they allow setting the floating point rounding mode 103and precision. 104.Pp 105The 106.Fn fpgetround 107function 108returns the current floating point rounding mode. 109.Pp 110The 111.Fn fpsetround 112function 113sets the floating point rounding mode and returns 114the previous mode. 115.Pp 116The 117.Fn fpgetprec 118function 119returns the current floating point precision. 120.Pp 121The 122.Fn fpsetprec 123function 124sets the floating point precision and returns 125the previous precision. 126.Pp 127The 128.Fn fpgetmask 129function 130returns the current floating point exception masks. 131.Pp 132The 133.Fn fpsetmask 134function 135sets the floating point exception masks and returns the 136previous masks. 137.Pp 138The 139.Fn fpgetsticky 140function 141returns the current floating point sticky flags. 142.Pp 143The 144.Fn fpresetsticky 145function 146clears the floating point sticky flags and returns 147the previous flags. 148.Pp 149Sample code which prevents a trap on divide-by-zero: 150.Bd -literal -offset indent 151fpsetmask(~FP_X_DZ); 152a = 1.0; 153b = 0; 154c = a / b; 155fpresetsticky(FP_X_DZ); 156fpsetmask(FP_X_DZ); 157.Ed 158.Sh SEE ALSO 159.Xr isnan 3 160.Sh CAVEAT 161After a floating point exception and before a mask is set, the sticky 162flags must be reset. If another exception occurs before the sticky 163flags are reset, then a wrong exception type may be signaled. 164.Sh HISTORY 165These routines are based on SysV/386 routines of the same name. 166