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///////////////////////////////////////////////////////////////////////////////////
// Copyright (C) 2016 Edouard Griffiths, F4EXB. //
// //
// This program 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 as version 3 of the License, or //
// //
// This program 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 V3 for more details. //
// //
// You should have received a copy of the GNU General Public License //
// along with this program. If not, see <http://www.gnu.org/licenses/>. //
///////////////////////////////////////////////////////////////////////////////////
#include <iostream>
#include "../fec.h"
void decode(DSDcc::Golay_20_8& Golay_20_8, unsigned char *codeword)
{
for (int i = 0; i < 20; i++)
{
std::cout << (int) codeword[i] << " ";
}
std::cout << std::endl;
if (Golay_20_8.decode(codeword))
{
for (int i = 0; i < 8; i++)
{
std::cout << (int) codeword[i] << " ";
}
std::cout << std::endl << "Decoding OK" << std::endl;
}
else
{
std::cout << "Decoding error" << std::endl;
}
}
void rand_test()
{
unsigned char msg[8];
unsigned char codeword[20], xcodeword[20];
int idx1, idx2, idx3;
int dataIn, dataOut;
int passCount = 0, failCount = 0, parityFailCount = 0;
DSDcc::Golay_20_8 golay_20_8;
// Run multiple times, to randomly corrupt different bits
// Takes about 10 seconds on a fast PC
for (int repeat = 0; repeat < 100000; repeat++)
{
// Exhaustively test all 8-bit inputs
for (int dataIn = 0; dataIn < 256; dataIn++)
{
// Convert to array of bits
for (int j = 0; j < 8; j++) {
msg[j] = (dataIn >> j) & 1;
}
// Encode
golay_20_8.encode(msg, codeword);
// Save copy of uncorrupted codeword
std::copy(codeword, codeword + 20, xcodeword);
// Randomly corrupt up to 3 bits
idx1 = rand() % 20;
idx2 = rand() % 20;
idx3 = rand() % 20;
codeword[idx1] ^= codeword[idx1];
codeword[idx2] ^= codeword[idx2];
codeword[idx3] ^= codeword[idx3];
bool fail = false;
// Decode and correct errors
dataOut = 0;
if (golay_20_8.decode(codeword))
{
// Check data is corrected
for (int j = 0; j < 8; j++) {
dataOut |= codeword[j] << j;
}
if (dataIn != dataOut) {
fail = true;
}
// Check also that parity has been corrected, as we previously had a bug with this
if (memcmp(codeword, xcodeword, 20)) {
parityFailCount++;
}
}
else
{
fail = true;
}
if (fail)
{
std::cout << "Decode failed:"
<< " dataIn=" << dataIn
<< " dataOut=" << dataOut
<< " idx1=" << idx1
<< " idx2=" << idx2
<< " idx3=" << idx3
<< "\n";
failCount++;
}
else
{
passCount++;
}
}
}
std::cout << "rand_test:"
<< " Passcount=" << passCount
<< " Failcount=" << failCount
<< " parityFailCount=" << parityFailCount << "\n";
}
int main(int argc, char *argv[])
{
unsigned char msg[8] = {1, 0, 0, 1, 0, 1, 0, 0};
unsigned char er0[20] = {0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
unsigned char codeword[20], xcodeword[20];
DSDcc::Golay_20_8 golay_20_8;
golay_20_8.encode(msg, codeword);
std::cout << "No errors" << std::endl;
decode(golay_20_8, codeword);
std::cout << std::endl << "Error on one bit (4)" << std::endl;
decode(golay_20_8, er0);
std::cout << std::endl << "Flip one bit (4)" << std::endl;
std::copy(codeword, codeword + 20, xcodeword);
xcodeword[4] ^= 1;
decode(golay_20_8, xcodeword);
std::cout << std::endl << "Flip one bit (15) in parity" << std::endl;
std::copy(codeword, codeword + 20, xcodeword);
xcodeword[15] ^= 1;
decode(golay_20_8, xcodeword);
std::cout << std::endl << "Flip two bits (1,5)" << std::endl;
std::copy(codeword, codeword + 20, xcodeword);
xcodeword[1] ^= 1;
xcodeword[5] ^= 1;
decode(golay_20_8, xcodeword);
std::cout << std::endl << "Flip two bits (1,15) - one in parity" << std::endl;
std::copy(codeword, codeword + 20, xcodeword);
xcodeword[1] ^= 1;
xcodeword[15] ^= 1;
decode(golay_20_8, xcodeword);
std::cout << std::endl << "Flip three bits (1,5,6)" << std::endl;
std::copy(codeword, codeword + 20, xcodeword);
xcodeword[1] ^= 1;
xcodeword[5] ^= 1;
xcodeword[6] ^= 1;
decode(golay_20_8, xcodeword);
std::cout << std::endl << "Flip three bits (1,5,9) - one in parity" << std::endl;
std::copy(codeword, codeword + 20, xcodeword);
xcodeword[1] ^= 1;
xcodeword[5] ^= 1;
xcodeword[9] ^= 1;
decode(golay_20_8, xcodeword);
std::cout << std::endl << "Flip three bits (1,15,21) - 2 in parity" << std::endl;
std::copy(codeword, codeword + 20, xcodeword);
xcodeword[1] ^= 1;
xcodeword[15] ^= 1;
xcodeword[19] ^= 1;
decode(golay_20_8, xcodeword);
std::cout << std::endl << "Flip three bits (15,18,21) - all parity" << std::endl;
std::copy(codeword, codeword + 20, xcodeword);
xcodeword[15] ^= 1;
xcodeword[18] ^= 1;
xcodeword[19] ^= 1;
decode(golay_20_8, xcodeword);
rand_test();
return 0;
}
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