dlib.core.bitio source code

1 /*
2 Copyright (c) 2015-2021 Timur Gafarov
3 
4 Boost Software License - Version 1.0 - August 17th, 2003
5 
6 Permission is hereby granted, free of charge, to any person or organization
7 obtaining a copy of the software and accompanying documentation covered by
8 this license (the "Software") to use, reproduce, display, distribute,
9 execute, and transmit the Software, and to prepare derivative works of the
10 Software, and to permit third-parties to whom the Software is furnished to
11 do so, all subject to the following:
12 
13 The copyright notices in the Software and this entire statement, including
14 the above license grant, this restriction and the following disclaimer,
15 must be included in all copies of the Software, in whole or in part, and
16 all derivative works of the Software, unless such copies or derivative
17 works are solely in the form of machine-executable object code generated by
18 a source language processor.
19 
20 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
21 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
22 FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
23 SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
24 FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
25 ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
26 DEALINGS IN THE SOFTWARE.
27 */
28 
29 /**
30  * Bit-level manipulations
31  *
32  * Copyright: Timur Gafarov 2015-2021.
33  * License: $(LINK2 https://boost.org/LICENSE_1_0.txt, Boost License 1.0).
34  * Authors: Timur Gafarov
35  */
36 module dlib.core.bitio;
37  
38 /**
39  * Endianness
40  */
41 enum Endian
42 {
43     Little,
44     Big
45 }
46 
47 /**
48  * Returns high 4 bits of a byte
49  */
50 T hiNibble(T)(T b)
51 {
52     return ((b >> 4) & 0x0F);
53 }
54 
55 ///
56 unittest
57 {
58     assert(hiNibble(0xFE) == 0x0F);
59 }
60 
61 /**
62  * Returns low 4 bits of a byte
63  */
64 T loNibble(T)(T b)
65 {
66     return (b & 0x0F);
67 }
68 
69 ///
70 unittest
71 {
72     assert(loNibble(0xFE) == 0x0E);
73 }
74 
75 /**
76  * Returns 16-bit integer n with swapped endianness
77  * TODO: move to dlib.math.utils
78  */
79 T swapEndian16(T)(T n)
80 {
81     return cast(T)((n >> 8) | (n << 8));
82 }
83 
84 ///
85 unittest
86 {
87     assert(swapEndian16(cast(ushort)0xFF00) == 0x00FF);
88 }
89 
90 /**
91  * Sets bit at position pos in integer b to state
92  */
93 T setBit(T)(T b, uint pos, bool state)
94 {
95     if (state)
96         return cast(T)(b | (1 << pos));
97     else
98         return cast(T)(b & ~(1 << pos));
99 }
100 
101 ///
102 unittest
103 {
104     assert(setBit(0, 0, true) == 1);
105     assert(setBit(1, 0, false) == 0);
106 }
107 
108 /**
109  * Returns bit at position pos in integer b
110  */
111 bool getBit(T)(T b, uint pos)
112 {
113     return ((b & (1 << pos)) != 0);
114 }
115 
116 ///
117 unittest
118 {
119     assert(getBit(1, 0) == 1);
120 }