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added BCH forward error correction

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This commit is contained in:
Ahmet Inan 2021-06-10 11:05:39 +02:00
commit 0e9f46efd1
3 changed files with 29 additions and 11 deletions
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18
decode.cc
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@ -25,6 +25,8 @@ namespace DSP { using std::abs; using std::min; using std::cos; using std::sin;
#include "crc.hh"
#include "osd.hh"
#include "psk.hh"
#include "galois_field.hh"
#include "bose_chaudhuri_hocquenghem_decoder.hh"
template <typename value, typename cmplx, int search_pos, int symbol_len, int guard_len>
struct SchmidlCox
@ -155,7 +157,7 @@ struct Decoder
static const int filter_len = (((21 * rate) / 8000) & ~3) | 1;
static const int guard_len = symbol_len / 8;
static const int code_bits = 64800;
static const int data_bits = code_bits - 32;
static const int data_bits = code_bits - 32 - 12 * 16;
static const int code_cols = 432;
static const int code_rows = code_bits / code_cols / Mod::BITS;
static const int code_off = -216;
@ -177,6 +179,9 @@ struct Decoder
SchmidlCox<value, cmplx, search_pos, symbol_len/2, guard_len> correlator;
CODE::CRC<uint16_t> crc0;
CODE::CRC<uint32_t> crc1;
typedef CODE::GaloisField<16, 0b10000000000101101, uint16_t> GF;
GF gf;
CODE::BoseChaudhuriHocquenghemDecoder<24, 1, 65343, GF> bchdec1;
CODE::OrderedStatisticsDecoder<255, 71, 4> osddec;
int8_t genmat[255*71];
cmplx head[symbol_len], tail[symbol_len];
@ -341,8 +346,15 @@ struct Decoder
}
}
}
int ret = bchdec1(out, out+(data_bits+32)/8, 0, 0, data_bits+32);
if (ret < 0) {
std::cerr << "payload BCH error." << std::endl;
return;
}
if (ret)
std::cerr << "payload BCH corrected " << ret << " errors." << std::endl;
crc1.reset();
for (int i = 0; i < code_bits / 8; ++i)
for (int i = 0; i < (data_bits+32)/8; ++i)
crc1(out[i]);
if (crc1())
std::cerr << "payload CRC error." << std::endl;
@ -399,7 +411,7 @@ int main(int argc, char **argv)
std::cerr << "Couldn't open file \"" << output_name << "\" for writing." << std::endl;
return 1;
}
const int data_len = code_len - 32 / 8;
const int data_len = code_len - (32 + 12 * 16) / 8;
for (int i = 0; i < data_len; ++i)
output_file.put(output_data[i]);
delete []output_data;