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.\" $FreeBSD$ 34.\" 35.Dd August 23, 1993 36.Dt FPGETROUND 3 37.Os 38.Sh NAME 39.Nm fpgetround , 40.Nm fpsetround , 41.Nm fpsetprec , 42.Nm fpgetprec , 43.Nm fpgetmask , 44.Nm fpsetmask , 45.Nm fpgetsticky , 46.Nm fpresetsticky 47.Nd IEEE floating point interface 48.Sh SYNOPSIS 49.In ieeefp.h 50.Pp 51.Bd -literal 52typedef enum { 53 FP_RN, /* round to nearest */ 54 FP_RM, /* round down to minus infinity */ 55 FP_RP, /* round up to plus infinity */ 56 FP_RZ /* truncate */ 57} fp_rnd_t; 58.Ed 59.Ft fp_rnd_t 60.Fn fpgetround void 61.Ft fp_rnd_t 62.Fn fpsetround "fp_rnd_t direction" 63.Pp 64.Bd -literal 65typedef enum { 66 FP_PS, /* 24 bit (single-precision) */ 67 FP_PRS, /* reserved */ 68 FP_PD, /* 53 bit (double-precision) */ 69 FP_PE /* 64 bit (extended-precision) */ 70} fp_prec_t; 71.Ed 72.Ft fp_prec_t 73.Fn fpgetprec void 74.Ft fp_prec_t 75.Fn fpsetprec "fp_prec_t precision" 76.Pp 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 96The routines described herein are deprecated. 97New code should use the functionality provided by 98.Xr fenv 3 . 99.Pp 100When a floating point exception is detected, the exception sticky flag is 101set and the exception mask is tested. 102If the mask is set, then a trap 103occurs. 104These routines allow both setting the floating point exception 105masks, and resetting the exception sticky flags after an exception is 106detected. 107In addition, they allow setting the floating point rounding mode 108and precision. 109.Pp 110The 111.Fn fpgetround 112function 113returns the current floating point rounding mode. 114.Pp 115The 116.Fn fpsetround 117function 118sets the floating point rounding mode and returns 119the previous mode. 120.Pp 121The 122.Fn fpgetprec 123function 124returns the current floating point precision. 125.Pp 126The 127.Fn fpsetprec 128function 129sets the floating point precision and returns 130the previous precision. 131.Pp 132The 133.Fn fpgetmask 134function 135returns the current floating point exception masks. 136.Pp 137The 138.Fn fpsetmask 139function 140sets the floating point exception masks and returns the 141previous masks. 142.Pp 143The 144.Fn fpgetsticky 145function 146returns the current floating point sticky flags. 147.Pp 148The 149.Fn fpresetsticky 150function 151clears the floating point sticky flags and returns 152the previous flags. 153.Pp 154Sample code which prevents a trap on divide-by-zero: 155.Bd -literal -offset indent 156fpsetmask(~FP_X_DZ); 157a = 1.0; 158b = 0; 159c = a / b; 160fpresetsticky(FP_X_DZ); 161fpsetmask(FP_X_DZ); 162.Ed 163.Sh IMPLEMENTATION NOTES 164The 165.Fn fpgetprec 166and 167.Fn fpsetprec 168functions provide functionality unavailable on many platforms. 169At present, they are implemented only on the i386 and amd64 platforms. 170.Sh SEE ALSO 171.Xr fenv 3 , 172.Xr isnan 3 173.Sh HISTORY 174These routines are based on SysV/386 routines of the same name. 175.Sh CAVEATS 176After a floating point exception and before a mask is set, the sticky 177flags must be reset. 178If another exception occurs before the sticky 179flags are reset, then a wrong exception type may be signaled. 180