1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
|
.\"
.\" Copyright (c) 2018 Netflix, Inc.
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions, and the following disclaimer,
.\" without modification, immediately at the beginning of the file.
.\" 2. The name of the author may not be used to endorse or promote products
.\" derived from this software without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
.\" ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.Dd July 8, 2018
.Dt Q_SIGNED 3
.Os
.Sh NAME
.Nm Q_SIGNED ,
.Nm Q_LTZ ,
.Nm Q_PRECEQ ,
.Nm Q_QLTQ ,
.Nm Q_QLEQ ,
.Nm Q_QGTQ ,
.Nm Q_QGEQ ,
.Nm Q_QEQ ,
.Nm Q_QNEQ ,
.Nm Q_OFLOW ,
.Nm Q_RELPREC
.Nd fixed-point math comparison and logic functions
.Sh SYNOPSIS
.In sys/qmath.h
.Ft bool
.Fn Q_SIGNED "NTYPE n"
.Ft bool
.Fn Q_LTZ "NTYPE n"
.Ft bool
.Fn Q_PRECEQ "QTYPE a" "QTYPE b"
.Ft bool
.Fn Q_QLTQ "QTYPE a" "QTYPE b"
.Ft bool
.Fn Q_QLEQ "QTYPE a" "QTYPE b"
.Ft bool
.Fn Q_QGTQ "QTYPE a" "QTYPE b"
.Ft bool
.Fn Q_QGEQ "QTYPE a" "QTYPE b"
.Ft bool
.Fn Q_QEQ "QTYPE a" "QTYPE b"
.Ft bool
.Fn Q_QNEQ "QTYPE a" "QTYPE b"
.Ft bool
.Fn Q_OFLOW "QTYPE q" "ITYPE iv"
.Ft int
.Fn Q_RELPREC "QTYPE a" "QTYPE b"
.Sh DESCRIPTION
.Fn Q_SIGNED
returns
.Ft true
if the numeric data type passed in as
.Fa n
is signed, or
.Ft false
otherwise.
.Pp
.Fn Q_LTZ
returns
.Ft true
if the numeric value
passed in as
.Fa n
is negative
.Pq requires types which use the MSB as the sign bit ,
or
.Ft false
otherwise.
.Pp
.Fn Q_PRECEQ
returns
.Ft true
if the number of
.Fa a
and
.Fa b
fractional bits is the same,
.Ft false
otherwise.
.Pp
The
.Fn Q_QLTQ ,
.Fn Q_QLEQ ,
.Fn Q_QGTQ ,
.Fn Q_QGEQ ,
.Fn Q_QEQ
and
.Fn Q_QNEQ
functions compare two Q numbers, returning
.Ft true
if
.Fa a
is less than, less than or equal to, greater than, greater than or equal to,
equal to, or not equal to
.Fa b
respectively, or
.Ft false
otherwise.
The integral and fractional values are used to perform the comparison, without
explicit concern for the underlying number of integer versus fractional bits.
.Pp
.Fn Q_OFLOW
returns
.Ft true
if integer value
.Fa iv
cannot be stored in
.Fa q
without truncation, or false otherwise.
.Pp
.Fn Q_RELPREC
returns the relative precision of
.Fa a
versus
.Fa b .
In terms of
.Em Qm.n
notation, this function returns the difference between the
.Em n
values of
.Fa a
and
.Fa b .
For example, a return value of +4 means that
.Fa a
has an additional 4 bits of fractional precision compared to
.Fa b .
.Pp
All of those functions operate on
the following data types:
.Vt s8q_t ,
.Vt u8q_t ,
.Vt s16q_t ,
.Vt u16q_t ,
.Vt s32q_t ,
.Vt u32q_t ,
.Vt s64q_t ,
and
.Vt u64q_t ,
which are referred to generically as
.Fa QTYPE .
The
.Fa ITYPE
refers to the
.Xr stdint 7
integer types.
.Fa NTYPE
is used to refer to any numeric type and is therefore a superset of
.Fa QTYPE
and
.Fa ITYPE .
.Pp
For more details, see
.Xr qmath 3 .
.Sh RETURN VALUES
The
.Fn Q_SIGNED ,
.Fn Q_LTZ ,
.Fn Q_PRECEQ ,
.Fn Q_QLTQ ,
.Fn Q_QLEQ ,
.Fn Q_QGTQ ,
.Fn Q_QGEQ ,
.Fn Q_QEQ ,
.Fn Q_QNEQ
and
.Fn Q_OFLOW
functions return expressions that evaluate to boolean
.Vt true
or
.Vt false .
.Pp
.Fn Q_RELPREC
returns the relative precision difference as a signed integer.
.Sh SEE ALSO
.Xr errno 2 ,
.Xr qmath 3 ,
.Xr stdint 7
.Sh HISTORY
The
.Xr qmath 3
functions first appeared in
.Fx 13.0 .
.Sh AUTHORS
.An -nosplit
The
.Xr qmath 3
functions and this manual page were written by
.An Lawrence Stewart Aq Mt lstewart@FreeBSD.org
and sponsored by Netflix, Inc.
|
