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
|
/*!
* \file
* \brief BCH encoder/decoder class test program
* \author Pal Frenger, Steve Peters and Adam Piatyszek
*
* -------------------------------------------------------------------------
*
* Copyright (C) 1995-2012 (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/itcomm.h>
#include "gtest/gtest.h"
using namespace itpp;
using namespace std;
bvec set_errors(const bvec &input, const ivec errpos)
{
bvec output = input;
for (int i = 0; i < errpos.length(); i++)
output(errpos(i)) ^= 1;
return output ;
}
TEST(BCH, codec)
{
ostringstream ss(ostringstream::out);
const string ref[] = {"encoded = [1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 0 0 1 0 1 1 0 1 0 0 0 0 1 1 0 0]",
"err = [1 1 0 1 1 0 0 1 1 1 1 1 0 0 1 0 0 1 0 1 1 0 1 0 0 0 0 1 1 0 0]",
"input = [0 1 0 0 0 1 1 1 0 1 0 1 1 1 0 1 0 0 1 1 0]",
"encoded = [0 1 1 1 0 0 1 1 1 1 1 1 0 1 0 0 1 0 1 1 0 0 1 1 1 0 1 0 1 1 0]",
"err = [0 0 0 1 0 0 1 1 1 1 1 1 0 1 0 0 1 0 1 1 0 0 1 1 1 0 1 1 1 1 0]",
"decoded = [0 0 0 1 1 0 0 1 0 0 0 1 0 1 1 1 0 1 1 1 0]",
"input = [1 0 1 1 0 0 0 1 1 0 1 0 0 1 1 1 1 1 1 0 0]",
"encoded = [1 0 1 1 0 0 0 1 1 0 1 0 0 1 1 1 0 1 0 1 0 1 0 0 1 0 0 0 1 0 1]",
"err = [1 1 0 1 0 0 0 1 1 0 1 0 0 1 0 1 0 1 0 1 0 1 0 0 1 0 0 1 1 0 1]",
"decoded = [1 1 0 1 0 0 0 1 1 0 1 0 0 1 0 1]"};
int i = 0;
{
BCH bch(31, 2);
RNG_reset(0);
bvec input = randb(21);
bvec encoded = bch.encode(input);
bvec err = set_errors(encoded, (ivec) "1 2"); // error positions
bvec decoded = bch.decode(err);
// A two error case (should be corrected)
ASSERT_TRUE(input == decoded);
ss << "encoded = " << encoded;
ASSERT_TRUE(ss.str() == ref[i++]);
ss.str("");
ss << "err = " << err;
ASSERT_TRUE(ss.str() == ref[i++]);
ss.str("");
input = randb(21);
encoded = bch.encode(input);
err = set_errors(encoded, (ivec) "1 2 27"); // error positions
decoded = bch.decode(err);
// A three error case (will cause decoding errors);
ss << "input = " << input;
ASSERT_TRUE(ss.str() == ref[i++]);
ss.str("");
ss << "encoded = " << encoded;
ASSERT_TRUE(ss.str() == ref[i++]);
ss.str("");
ss << "err = " << err;
ASSERT_TRUE(ss.str() == ref[i++]);
ss.str("");
ss << "decoded = " << decoded;
ASSERT_TRUE(ss.str() == ref[i++]);
ss.str("");
}
// Systematic vs. non-systematic test
{
bmat u = "0 0 0 0; 0 0 0 1; 0 0 1 0; 0 0 1 1; 0 1 0 0; 0 1 0 1; 0 1 1 0";
bmat c(u.rows(), 7);
bmat y(u.rows(), 7);
bmat decoded(u.rows(), u.cols());
BCH bch_nsys(7, 1);
BCH bch_sys(7, 1, true);
bmat f = "1 0 0 0 0 0 0; 0 1 0 0 0 0 0; 0 0 1 0 0 0 0; 0 0 0 1 0 0 0; 0 0 0 0 1 0 0; 0 0 0 0 0 1 0; 0 0 0 0 0 0 1";
// Non-systematic case
for (int i = 0; i < u.rows(); i++) {
c.set_row(i, bch_nsys.encode(u.get_row(i)));
y.set_row(i, f.get_row(i) + c.get_row(i));
decoded.set_row(i, bch_nsys.decode(y.get_row(i)));
}
ASSERT_TRUE(u == decoded);
// Systematic case
for (int i = 0; i < u.rows(); i++) {
c.set_row(i, bch_sys.encode(u.get_row(i)));
y.set_row(i, f.get_row(i) + c.get_row(i));
decoded.set_row(i, bch_sys.decode(y.get_row(i)));
}
ASSERT_TRUE(u == decoded);
}
// Systematic decoding failure test
{
BCH bch(31, 3, true);
bvec input = randb(21);
bvec encoded = bch.encode(input);
bvec err = set_errors(encoded, (ivec) "1 2 14 27"); // error positions
bvec decoded;
bvec is_valid_cw; // test the new decoding procedure for the systematic case (should extract the systematics)
// all codewords valid?
ASSERT_FALSE(bch.decode(err, decoded, is_valid_cw));
// valid codeword?
ASSERT_TRUE(bvec("0") == is_valid_cw);
// A four error case (will cause decoding failure)
ss << "input = " << input;
ASSERT_TRUE(ss.str() == ref[i++]);
ss.str("");
ss << "encoded = " << encoded;
ASSERT_TRUE(ss.str() == ref[i++]);
ss.str("");
ss << "err = " << err;
ASSERT_TRUE(ss.str() == ref[i++]);
ss.str("");
ss << "decoded = " << decoded;
ASSERT_TRUE(ss.str() == ref[i++]);
}
}
|
