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/*

Maximum length sequence

Copyright 2020 Ahmet Inan <inan@aicodix.de>

*/

#pragma once

namespace CODE {

class MLS

{

static int hibit(unsigned n)

{

n |= n >> 1;

n |= n >> 2;

n |= n >> 4;

n |= n >> 8;

n |= n >> 16;

return n ^ (n >> 1);

}

int poly, test, reg;

public:

MLS(int poly = 0b100000000000000001001, int reg = 1) : poly(poly), test(hibit(poly)>>1), reg(reg) {}

void reset(int r = 1)

{

reg = r;

}

int length()

{

return hibit(poly) - 1;

}

bool bad(int r = 1)

{

reg = r;

int len = length();

for (int i = 1; i < len; ++i) {

(*this)();

if (reg == r)

return true;

}

(*this)();

return reg != r;

}

int next()

{

(*this)();

return reg;

}

bool operator()()

{

bool fb = reg & test;

reg <<= 1;

reg ^= fb * poly;

return fb;

}

};

}