1.\"	$OpenBSD: fpgetmask.3,v 1.10 2015/09/14 15:14:55 schwarze Exp $
2.\"	$NetBSD: fpgetmask.3,v 1.3 2001/09/16 02:57:03 wiz Exp $
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31.Dd $Mdocdate: September 14 2015 $
32.Dt FPGETMASK 3
33.Os
34.Sh NAME
35.Nm fpgetmask ,
36.Nm fpgetround ,
37.Nm fpgetsticky ,
38.Nm fpsetmask ,
39.Nm fpsetround ,
40.Nm fpsetsticky
41.Nd IEEE FP mode control
42.Sh SYNOPSIS
43.In ieeefp.h
44.Ft fp_except
45.Fn fpgetmask void
46.Ft fp_rnd
47.Fn fpgetround void
48.Ft fp_except
49.Fn fpgetsticky void
50.Ft fp_except
51.Fn fpsetmask "fp_except mask"
52.Ft fp_rnd
53.Fn fpsetround "fp_rnd rnd_dir"
54.Ft fp_except
55.Fn fpsetsticky "fp_except sticky"
56.Sh DESCRIPTION
57A rounding mode is one of
58.Dv FP_RZ , FP_RM , FP_RN ,
59or
60.Dv FP_RP ,
61for rounding towards zero, rounding
62.Pq Em Minus infinity
63down, rounding to
64.Em nearest ,
65and rounding
66.Pq Em Plus infinity
67up.
68The default mode is
69.Dv FP_RN .
70.Pp
71An
72.Ft fp_except
73value is a bitmask specifying an exception type and containing any of
74the values listed below.
75.Bl -column FP_X_UFLxx -offset indent
76.It Dv FP_X_INV Ta Invalid\ Operation
77.It Dv FP_X_DZ Ta Division\ by\ zero
78.It Dv FP_X_OFL Ta Overflow
79.It Dv FP_X_UFL Ta Underflow
80.It Dv FP_X_IMP Ta Imprecision (inexact)
81.It Dv FP_X_DNML Ta Denormalization Pq amd64 and i386 only
82.El
83.Pp
84The
85.Fn fpsetmask
86function will cause future operations with the specified result status to
87raise the
88.Dv SIGFPE
89exception.
90The
91.Fn fpsetround
92function will cause future operations to use the specified dynamic mode.
93.Bl -tag -width Note:x
94.It Em Note :
95On some architectures, instructions can optionally specify static
96rounding modes and exception enables that will supersede the specified
97dynamic mode.
98On other architectures, these features may not be fully supported.
99.El
100.Pp
101The
102.Fn fpsetsticky
103function will set or clear the specified exception history bits.
104.Sh RETURN VALUES
105The
106.Fn fpgetround
107and
108.Fn fpsetround
109functions return the
110.Pq previous
111rounding mode.
112The
113.Fn fpgetmask ,
114.Fn fpsetmask ,
115.Fn fpgetsticky ,
116and
117.Fn fpsetsticky
118functions return the
119.Pq previous
120exception mask and exception history bits.
121.Sh SEE ALSO
122.Xr sigaction 2
123