1 .\" Copyright (c) 1993 Andrew Moore, Talke Studio
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28 .\" @(#)fpgetround.3 1.0 (Berkeley) 9/23/93
29 .\" $FreeBSD: src/share/man/man3/fpgetround.3,v 1.15 2005/07/15 17:35:25 hrs Exp $
30 .\" $DragonFly: src/share/man/man3/fpgetround.3,v 1.4 2008/05/02 02:05:05 swildner Exp $
45 .Nd IEEE floating point interface
52 FP_RN, /* round to nearest */
53 FP_RM, /* round down to minus infinity */
54 FP_RP, /* round up to plus infinity */
61 .Fn fpsetround "fp_rnd_t direction"
64 FP_PS, /* 24 bit (single-precision) */
65 FP_PRS, /* reserved */
66 FP_PD, /* 53 bit (double-precision) */
67 FP_PE /* 64 bit (extended-precision) */
73 .Fn fpsetprec "fp_prec_t precision"
75 #define fp_except_t int
76 #define FP_X_INV 0x01 /* invalid operation */
77 #define FP_X_DNML 0x02 /* denormal */
78 #define FP_X_DZ 0x04 /* zero divide */
79 #define FP_X_OFL 0x08 /* overflow */
80 #define FP_X_UFL 0x10 /* underflow */
81 #define FP_X_IMP 0x20 /* (im)precision */
82 #define FP_X_STK 0x40 /* stack fault */
87 .Fn fpsetmask "fp_except_t mask"
91 .Fn fpsetsticky "fp_except_t sticky"
93 .Fn fpresetsticky "fp_except_t sticky"
95 The routines described herein are deprecated.
96 New code should use the functionality provided by
99 When a floating point exception is detected, the exception sticky flag is
100 set and the exception mask is tested.
101 If the mask is set, then a trap occurs.
102 These routines allow both setting the floating point exception
103 masks, and resetting the exception sticky flags after an exception is
105 In addition, they allow setting the floating point rounding mode
111 returns the current floating point rounding mode.
116 sets the floating point rounding mode and returns
122 returns the current floating point precision.
127 sets the floating point precision and returns
128 the previous precision.
133 returns the current floating point exception masks.
138 sets the floating point exception masks and returns the
144 returns the current floating point sticky flags.
148 sets the floating point sticky flags and returns
154 clears the floating point sticky flags and returns
157 Sample code which prevents a trap on divide-by-zero:
158 .Bd -literal -offset indent
163 fpresetsticky(FP_X_DZ);
166 .Sh IMPLEMENTATION NOTES
171 functions provide functionality unavailable on many platforms.
172 At present, they are implemented only on the i386 and x86_64 platforms.
177 After a floating point exception and before a mask is set, the sticky
179 If another exception occurs before the sticky
180 flags are reset, then a wrong exception type may be signaled.
182 These routines are based on SysV/386 routines of the same name.