1 /*
2  *  Copyright (c) 2016, The OpenThread Authors.
3  *  All rights reserved.
4  *
5  *  Redistribution and use in source and binary forms, with or without
6  *  modification, are permitted provided that the following conditions 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. Neither the name of the copyright holder nor the
13  *     names of its contributors may be used to endorse or promote products
14  *     derived from this software without specific prior written permission.
15  *
16  *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
17  *  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18  *  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19  *  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
20  *  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
21  *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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25  *  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
26  *  POSSIBILITY OF SUCH DAMAGE.
27  */
28 
29 /**
30  * @file
31  *   This file includes definitions for CRC16 computations.
32  */
33 
34 #ifndef CRC16_HPP_
35 #define CRC16_HPP_
36 
37 #include "openthread-core-config.h"
38 
39 #include <stdint.h>
40 
41 namespace ot {
42 
43 /**
44  * Implements CRC16 computations.
45  *
46  */
47 class Crc16
48 {
49 public:
50     enum Polynomial : uint16_t
51     {
52         kCcitt = 0x1021, ///< CRC16_CCITT
53         kAnsi  = 0x8005, ///< CRC16-ANSI
54     };
55 
56     /**
57      * Initializes the object.
58      *
59      * @param[in]  aPolynomial  The polynomial value.
60      *
61      */
62     explicit Crc16(Polynomial aPolynomial);
63 
64     /**
65      * Initializes the CRC16 computation.
66      *
67      */
Init(void)68     void Init(void) { mCrc = 0; }
69 
70     /*c*
71      * Feeds a byte value into the CRC16 computation.
72      *
73      * @param[in]  aByte  The byte value.
74      *
75      */
76     void Update(uint8_t aByte);
77 
78     /**
79      * Gets the current CRC16 value.
80      *
81      * @returns The current CRC16 value.
82      *
83      */
Get(void) const84     uint16_t Get(void) const { return mCrc; }
85 
86 private:
87     uint16_t mPolynomial;
88     uint16_t mCrc;
89 };
90 
91 } // namespace ot
92 
93 #endif // CRC16_HPP_
94