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/* -*- c++ -*- */
/* Copyright 2016 Free Software Foundation, Inc.
*
* This file is part of GNU Radio
*
* SPDX-License-Identifier: GPL-3.0-or-later
*
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <gnuradio/digital/header_buffer.h>
#include <gnuradio/digital/header_format_ofdm.h>
#include <gnuradio/digital/lfsr.h>
#include <volk/volk.h>
#include <cstring>
namespace gr {
namespace digital {
header_format_ofdm::sptr
header_format_ofdm::make(const std::vector<std::vector<int>>& occupied_carriers,
int n_syms,
const std::string& len_key_name,
const std::string& frame_key_name,
const std::string& num_key_name,
int bits_per_header_sym,
int bits_per_payload_sym,
bool scramble_header)
{
return header_format_ofdm::sptr(new header_format_ofdm(occupied_carriers,
n_syms,
len_key_name,
frame_key_name,
num_key_name,
bits_per_header_sym,
bits_per_payload_sym,
scramble_header));
}
header_format_ofdm::header_format_ofdm(
const std::vector<std::vector<int>>& occupied_carriers,
int n_syms,
const std::string& len_key_name,
const std::string& frame_key_name,
const std::string& num_key_name,
int bits_per_header_sym,
int bits_per_payload_sym,
bool scramble_header)
: header_format_crc(len_key_name, num_key_name),
d_frame_key_name(pmt::intern(frame_key_name)),
d_occupied_carriers(occupied_carriers),
d_bits_per_payload_sym(bits_per_payload_sym)
{
d_header_len = 0;
for (int i = 0; i < n_syms; i++) {
d_header_len += occupied_carriers[i].size();
}
d_syms_per_set = 0;
for (unsigned i = 0; i < d_occupied_carriers.size(); i++) {
d_syms_per_set += d_occupied_carriers[i].size();
}
// Init scrambler mask
d_scramble_mask = std::vector<uint8_t>(header_nbits(), 0);
if (scramble_header) {
// These are just random values which already have OK PAPR:
gr::digital::lfsr shift_reg(0x8a, 0x6f, 7);
for (size_t i = 0; i < header_nbytes(); i++) {
for (int k = 0; k < bits_per_header_sym; k++) {
d_scramble_mask[i] ^= shift_reg.next_bit() << k;
}
}
}
}
header_format_ofdm::~header_format_ofdm() {}
bool header_format_ofdm::format(int nbytes_in,
const unsigned char* input,
pmt::pmt_t& output,
pmt::pmt_t& info)
{
bool ret_val = header_format_crc::format(nbytes_in, input, output, info);
// size_t len;
// uint8_t *out = pmt::u8vector_writable_elements(output, len);
// for(size_t i = 0; i < len; i++) {
// out[i] ^= d_scramble_mask[i];
//}
return ret_val;
}
bool header_format_ofdm::parse(int nbits_in,
const unsigned char* input,
std::vector<pmt::pmt_t>& info,
int& nbits_processed)
{
int index = 0;
while (nbits_processed <= nbits_in) {
d_hdr_reg.insert_bit(input[nbits_processed++] ^ d_scramble_mask[index++]);
if (d_hdr_reg.length() == header_nbits()) {
if (header_ok()) {
int payload_len = header_payload();
enter_have_header(payload_len);
info.push_back(d_info);
d_hdr_reg.clear();
return true;
} else {
d_hdr_reg.clear();
return false;
}
break;
}
}
return true;
}
size_t header_format_ofdm::header_nbits() const { return d_header_len; }
int header_format_ofdm::header_payload()
{
uint32_t pkt = d_hdr_reg.extract_field32(0, 24, true);
uint16_t pktlen = static_cast<uint16_t>((pkt >> 8) & 0x0fff);
uint16_t pktnum = static_cast<uint16_t>((pkt >> 20) & 0x0fff);
// Convert num bytes to num complex symbols in payload
pktlen *= 8;
uint16_t pldlen = pktlen / d_bits_per_payload_sym;
if (pktlen % d_bits_per_payload_sym) {
pldlen++;
}
// frame_len = # of OFDM symbols in this frame
int framelen = pldlen / d_syms_per_set;
int k = 0;
int i = framelen * d_syms_per_set;
while (i < pldlen) {
framelen++;
// i += d_occupied_carriers[k++].size();
i += d_occupied_carriers[k].size();
}
d_info = pmt::make_dict();
d_info = pmt::dict_add(d_info, d_len_key_name, pmt::from_long(pldlen));
d_info = pmt::dict_add(d_info, d_num_key_name, pmt::from_long(pktnum));
d_info = pmt::dict_add(d_info, d_frame_key_name, pmt::from_long(framelen));
return static_cast<int>(pldlen);
}
} /* namespace digital */
} /* namespace gr */
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