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47 lines
848 B
C++
47 lines
848 B
C++
/*
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Encoder for short BCH codes
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Copyright 2020 Ahmet Inan <inan@aicodix.de>
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*/
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#pragma once
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namespace CODE {
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template <int N, int K, int G>
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class ShortBCHCodeEncoder
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{
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static const int P = N - K;
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static const int W = 1 << K;
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short par[W];
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static_assert(N < 8 * sizeof(int), "codeword type not wide enough");
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static_assert(P < 8 * sizeof(par[0]), "parity type not wide enough");
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static int modgen(int inp)
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{
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for (int i = K-1; i >= 0; --i) {
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int tmp = inp >> (i+P);
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inp ^= (tmp & 1) * (G << i);
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}
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return inp;
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}
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public:
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ShortBCHCodeEncoder()
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{
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for (int i = 0; i < W; ++i)
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par[i] = modgen(i << P);
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}
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int operator()(int msg)
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{
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return (msg << P) | par[msg];
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}
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int operator()(int8_t *code, int msg)
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{
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int cw = (*this)(msg);
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for (int i = 0; i < N; ++i)
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code[i] = 1 - 2 * ((cw >> i) & 1);
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return cw;
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}
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};
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}
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