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
|
/*!
* \file
* \brief Implementation of a CRC code class
* \author Tony Ottosson
*
* -------------------------------------------------------------------------
*
* Copyright (C) 1995-2010 (see AUTHORS file for a list of contributors)
*
* This file is part of IT++ - a C++ library of mathematical, signal
* processing, speech processing, and communications classes and functions.
*
* IT++ is free software: you can redistribute it and/or modify it under the
* terms of the GNU General Public License as published by the Free Software
* Foundation, either version 3 of the License, or (at your option) any
* later version.
*
* IT++ is distributed in the hope that it will be useful, but WITHOUT ANY
* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License along
* with IT++. If not, see <http://www.gnu.org/licenses/>.
*
* -------------------------------------------------------------------------
*/
#include <itpp/comm/crc.h>
#include <itpp/base/specmat.h>
#include <itpp/base/matfunc.h>
namespace itpp
{
void CRC_Code::set_generator(const bvec &poly)
{
//it_assert(poly(0) == 1 && poly(poly.size()-1) == 1, "CRC_Code::set_polynomial: not a valid polynomial");
it_assert(poly(0) == 1, "CRC_Code::set_polynomial: not a valid polynomial");
polynomial = poly;
no_parity = polynomial.size() - 1;
}
//! \cond
std::string crccode[18][2] = {
{"CRC-4", "1 1 1 1 1"},
{"CRC-7", "1 1 0 1 0 0 0 1"},
{"CRC-8", "1 1 1 0 1 0 1 0 1"},
{"CRC-12", "1 1 0 0 0 0 0 0 0 1 1 1 1"},
{"CRC-24", "1 1 0 0 0 0 0 0 0 0 1 0 1 0 0 0 1 0 0 0 0 0 0 0 1"},
{"CRC-32", "1 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0 1 0 0 1 1 0 0 0 1 1 1 0 0 0 1 0"},
{"CCITT-4", "1 0 0 1 1"},
{"CCITT-5", "1 1 0 1 0 1"},
{"CCITT-6", "1 0 0 0 0 1 1"},
{"CCITT-16", "1 0 0 0 1 0 0 0 0 0 0 1 0 0 0 0 1"},
{"CCITT-32", "1 0 0 0 0 0 1 0 0 1 1 0 0 0 0 0 1 0 0 0 1 1 1 0 1 1 0 1 1 0 1 1 1"},
{"WCDMA-8", "1 1 0 0 1 1 0 1 1"},
{"WCDMA-12", "1 1 0 0 0 0 0 0 0 1 1 1 1"},
{"WCDMA-16", "1 0 0 0 1 0 0 0 0 0 0 1 0 0 0 0 1"},
{"WCDMA-24", "1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 1 1"},
{"ATM-8", "1 0 0 0 0 0 1 1 1"},
{"ANSI-16", "1 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1"},
{"SDLC-16", "1 1 0 1 0 0 0 0 0 1 0 0 1 0 1 1 1"},
};
//! \endcond
void CRC_Code::set_code(const std::string &code)
{
bvec poly;
for (int i = 0; i < 18;i++) {
if (crccode[i][0] == code)
poly = bvec(crccode[i][1]);
}
if ((code == "WCDMA-8") || (code == "WCDMA-12") || (code == "WCDMA-16") || (code == "WCDMA-24")) {
reverse_parity = true;
}
it_assert(poly.size() > 0, "This CRC code doesn't exist in the tables");
set_generator(poly);
}
// Not optimized for speed!
void CRC_Code::parity(const bvec &in_bits, bvec &out) const
{
bvec temp = concat(in_bits, zeros_b(no_parity));
for (int i = 0; i < temp.size() - polynomial.size() + 1; i++) {
if (temp(i) == 1) {
temp.set_subvector(i, temp(i, i + no_parity) + polynomial);
}
}
out = temp(temp.size() - no_parity, temp.size() - 1);
if (reverse_parity) {
out = reverse(out);
}
}
// Not optimized for speed
bool CRC_Code::check_parity(const bvec &coded_bits) const
{
int n = coded_bits.size();
bvec temp;
if (reverse_parity) {
temp = concat(coded_bits.left(n - no_parity), reverse(coded_bits.right(no_parity)));
}
else {
temp = coded_bits;
}
for (int i = 0; i < temp.size() - polynomial.size() + 1; i++) {
if (temp(i) == 1) {
temp.set_subvector(i, temp(i, i + no_parity) + polynomial);
}
}
if (temp(temp.size() - no_parity, temp.size() - 1) == zeros_b(no_parity))
return true;
else
return false;
}
void CRC_Code::encode(const bvec &in_bits, bvec &out) const
{
bvec p;
parity(in_bits, p);
out = concat(in_bits, p);
}
bvec CRC_Code::encode(const bvec &in_bits) const
{
bvec temp;
encode(in_bits, temp);
return temp;
}
bool CRC_Code::decode(const bvec &coded_bits, bvec &out) const
{
out = coded_bits(0, coded_bits.size() - no_parity - 1);
if (check_parity(coded_bits)) {
return true;
}
else
return false;
}
bool CRC_Code::decode(bvec &coded_bits) const
{
//coded_bits = coded_bits(0, coded_bits.size()-no_parity-1); <-- OLD CODE
if (check_parity(coded_bits)) {
return true;
}
else
return false;
}
} // namespace itpp
|
