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added LDPC encoder and layered decoder

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lifted from my LDPC project:
https://github.com/xdsopl/LDPC
This commit is contained in:
Ahmet Inan 2018-12-11 16:29:47 +01:00
commit 199a988def
4 changed files with 536 additions and 0 deletions
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ldpc_encoder.hh Normal file
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/*
LDPC SISO encoder
Copyright 2018 Ahmet Inan <inan@aicodix.de>
*/
#ifndef LDPC_ENCODER_HH
#define LDPC_ENCODER_HH
namespace CODE {
template <typename TABLE>
class LDPCEncoder
{
static const int M = TABLE::M;
static const int N = TABLE::N;
static const int K = TABLE::K;
static const int R = N-K;
static const int q = R/M;
static const int CNC = TABLE::LINKS_MAX_CN - 2;
uint16_t pos[R * CNC];
uint8_t cnc[R];
public:
LDPCEncoder()
{
for (int i = 0; i < R; ++i)
cnc[i] = 0;
int bit_pos = 0;
const int *row_ptr = TABLE::POS;
for (int g = 0; TABLE::LEN[g]; ++g) {
int bit_deg = TABLE::DEG[g];
for (int r = 0; r < TABLE::LEN[g]; ++r) {
int acc_pos[bit_deg];
for (int d = 0; d < bit_deg; ++d)
acc_pos[d] = row_ptr[d];
row_ptr += bit_deg;
for (int j = 0; j < M; ++j) {
for (int d = 0; d < bit_deg; ++d) {
int n = acc_pos[d];
pos[CNC*n+cnc[n]++] = bit_pos;
}
++bit_pos;
for (int d = 0; d < bit_deg; ++d)
acc_pos[d] = (acc_pos[d] + q) % R;
}
}
}
}
void operator()(int8_t *data, int8_t *parity)
{
int8_t tmp = 1;
for (int i = 0; i < R; ++i) {
for (int j = 0; j < cnc[i]; ++j)
tmp *= data[pos[CNC*i+j]];
parity[i] = tmp;
}
}
};
}
#endif