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/*

Test for the short BCH codes encoder

Copyright 2020 Ahmet Inan <inan@aicodix.de>

*/

#include <cassert>

#include <iostream>

#include "short_bch_code_encoder.hh"

template<typename TYPE>

int popcnt(TYPE x)

{

int cnt = 0;

while (x) {

++cnt;

x &= x-1;

}

return cnt;

}

template <int N, int K, int T, int POLY>

void bch_test(int message, int target)

{

CODE::ShortBCHCodeEncoder<N, K, POLY> encode;

int hist[N+1] = { 0 };

for (int j = 0; j < (1 << K); ++j)

for (int i = j + 1; i < (1 << K); ++i)

++hist[popcnt(encode(i)^encode(j))];

std::cout << "BCH(" << N << ", " << K << ") T=" << T << " hist:";

for (int i = 0; i < N + 1; ++i)

if (hist[i])

std::cout << " " << i << ":" << hist[i];

std::cout << std::endl;

int d = 0;

while (!hist[d])

++d;

assert((d-1)/2 == T);

int codeword = encode(message);

assert(target == codeword);

}

int main()

{

if (1) {

// Perfect binary Golay code using x^11+x^9+x^7+x^6+x^5+x+1

bch_test<23, 12, 3, 0b101011100011>(0b101011011011, 0b10101101101111011111001);

}

if (1) {

// Perfect binary Golay code using x^11+x^10+x^6+x^5+x^4+x^2+1

bch_test<23, 12, 3, 0b110001110101>(0b101011011011, 0b10101101101100100010101);

}

if (1) {

// NASA INTRO BCH(15, 5) T=3

bch_test<15, 5, 3, 0b10100110111>(0b11001, 0b110010001111010);

}

if (1) {

// BCH(31, 16) T=3

bch_test<31, 16, 3, 0b1000111110101111>(29619, 970576025);

}

std::cerr << "Short BCH code encoder test passed!" << std::endl;

return 0;

}