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added LDPC forward error correction

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Ahmet Inan 2021-06-10 14:51:25 +02:00
commit 7ba95fb000
4 changed files with 182 additions and 25 deletions
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encode.cc
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@ -17,17 +17,19 @@ Copyright 2021 Ahmet Inan <inan@aicodix.de>
#include "mls.hh"
#include "crc.hh"
#include "psk.hh"
#include "ldpc_tables.hh"
#include "ldpc_encoder.hh"
#include "galois_field.hh"
#include "bose_chaudhuri_hocquenghem_encoder.hh"
template <typename value, typename cmplx, int rate>
struct Encoder
{
typedef PhaseShiftKeying<8, cmplx, value> Mod;
typedef PhaseShiftKeying<8, cmplx, int8_t> Mod;
static const int symbol_len = (1280 * rate) / 8000;
static const int guard_len = symbol_len / 8;
static const int code_bits = 64800;
static const int data_bits = code_bits - 32 - 12 * 16;
static const int data_bits = code_bits - 32 - 12 * 16 - 21600;
static const int code_cols = 432;
static const int code_rows = code_bits / code_cols / Mod::BITS;
static const int mls0_len = 127;
@ -41,6 +43,8 @@ struct Encoder
CODE::CRC<uint32_t> crc1;
CODE::BoseChaudhuriHocquenghemEncoder<255, 71> bchenc0;
CODE::BoseChaudhuriHocquenghemEncoder<65535, 65343> bchenc1;
CODE::LDPCEncoder<DVB_T2_TABLE_A3> ldpcenc;
int8_t code[code_bits];
cmplx fdom[symbol_len];
cmplx tdom[symbol_len];
cmplx guard[guard_len];
@ -87,7 +91,7 @@ struct Encoder
for (int i = 0; i < symbol_len; ++i)
fdom[i] = 0;
for (int i = code_off; i < code_off + code_cols; ++i) {
value tmp[Mod::BITS];
int8_t tmp[Mod::BITS];
for (int k = 0; k < Mod::BITS; ++k)
tmp[k] = 1 - 2 * seq2();
fdom[bin(i)] = code_fac * Mod::map(tmp);
@ -159,15 +163,12 @@ struct Encoder
for (int i = 0; i < 4; ++i)
inp[data_bits/8+i] = (crc1() >> (8*i)) & 255;
bchenc1(inp, inp+(data_bits+32)/8, data_bits+32);
for (int i = 0; i < data_bits+32+12*16; ++i)
code[i] = 1 - 2 * CODE::get_le_bit(inp, i);
ldpcenc(code, code+data_bits+32+12*16);
for (int j = 0; j < code_rows; ++j) {
for (int i = 0; i < code_cols; ++i) {
value tmp[Mod::BITS];
for (int k = 0; k < Mod::BITS; ++k) {
int l = Mod::BITS * (code_cols * j + i) + k;
tmp[k] = 1 - 2 * CODE::get_le_bit(inp, l);
}
fdom[bin(i+code_off)] *= Mod::map(tmp);
}
for (int i = 0; i < code_cols; ++i)
fdom[bin(i+code_off)] *= Mod::map(code+Mod::BITS*(code_cols*j+i));
symbol();
}
schmidl_cox();
@ -239,7 +240,7 @@ int main(int argc, char **argv)
return 1;
}
const int code_len = 64800 / 8;
const int data_len = code_len - (32 + 12 * 16) / 8;
const int data_len = code_len - (32 + 12 * 16 + 21600) / 8;
uint8_t *input_data = new uint8_t[code_len];
for (int i = 0; i < data_len; ++i)
input_data[i] = input_file.get();