393 lines
12 KiB
C++
393 lines
12 KiB
C++
/* -*- c++ -*- */
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/*
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* gr-satnogs: SatNOGS GNU Radio Out-Of-Tree Module
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*
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* Copyright (C) 2018, Libre Space Foundation <http://librespacefoundation.org/>
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include <gnuradio/io_signature.h>
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#include "frame_acquisition_impl.h"
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#include <satnogs/golay24.h>
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namespace gr
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{
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namespace satnogs
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{
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frame_acquisition::sptr
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frame_acquisition::make_generic_var_len (const std::vector<uint8_t>& preamble,
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size_t preamble_threshold,
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const std::vector<uint8_t>& sync,
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size_t sync_threshold,
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size_t frame_size_len,
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checksum_t crc,
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whitening::sptr descrambler,
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size_t max_frame_len)
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{
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return gnuradio::get_initial_sptr (
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new frame_acquisition_impl (frame_acquisition_impl::GENERIC_VAR_FRAME_LEN,
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preamble,
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preamble_threshold, sync, sync_threshold,
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frame_size_len, 0, crc, descrambler,
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max_frame_len));
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}
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frame_acquisition::sptr
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frame_acquisition::make_generic_const_len (const std::vector<uint8_t>& preamble,
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size_t preamble_threshold,
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const std::vector<uint8_t>& sync,
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size_t sync_threshold,
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size_t frame_len, checksum_t crc,
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whitening::sptr descrambler,
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size_t max_frame_len)
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{
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return gnuradio::get_initial_sptr (
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new frame_acquisition_impl (frame_acquisition_impl::GENERIC_CONSTANT_FRAME_LEN,
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preamble,
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preamble_threshold, sync, sync_threshold,
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0, frame_len, crc, descrambler,
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max_frame_len));
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}
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frame_acquisition::sptr
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frame_acquisition::make_golay24_var_len (const std::vector<uint8_t>& preamble,
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size_t preamble_threshold,
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const std::vector<uint8_t>& sync,
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size_t sync_threshold, checksum_t crc,
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whitening::sptr descrambler,
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size_t max_frame_len)
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{
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return gnuradio::get_initial_sptr (
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new frame_acquisition_impl (frame_acquisition_impl::GOLAY24_CODED_FRAME_LEN,
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preamble,
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preamble_threshold, sync, sync_threshold,
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0, 0, crc, descrambler,
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max_frame_len));
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}
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frame_acquisition_impl::frame_acquisition_impl (variant_t variant,
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const std::vector<uint8_t>& preamble,
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size_t preamble_threshold,
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const std::vector<uint8_t>& sync,
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size_t sync_threshold,
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size_t frame_size_len,
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size_t frame_len,
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checksum_t crc,
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whitening::sptr descrambler,
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size_t max_frame_len) :
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gr::sync_block ("frame_acquisition",
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gr::io_signature::make (1, 1, sizeof(uint8_t)),
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gr::io_signature::make (0, 0, 0)),
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d_variant(variant),
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d_preamble(preamble.size() * 8),
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d_preamble_shift_reg(preamble.size() * 8),
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d_preamble_len(preamble.size() * 8),
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d_preamble_thrsh(preamble_threshold),
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d_sync(sync.size() * 8),
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d_sync_shift_reg(sync.size() * 8),
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d_sync_len(sync.size() * 8),
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d_sync_thrsh(sync_threshold),
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d_state(SEARCHING),
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d_cnt(0),
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d_frame_size_field_len(frame_size_len),
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d_frame_len(frame_len),
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d_max_frame_len(max_frame_len),
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d_crc(crc),
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d_whitening(descrambler)
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{
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set_output_multiple(8);
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for(uint8_t b : preamble) {
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d_preamble <<= (b >> 7);
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d_preamble <<= ((b >> 6) & 0x1);
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d_preamble <<= ((b >> 6) & 0x1);
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d_preamble <<= ((b >> 5) & 0x1);
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d_preamble <<= ((b >> 4) & 0x1);
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d_preamble <<= ((b >> 3) & 0x1);
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d_preamble <<= ((b >> 2) & 0x1);
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d_preamble <<= ((b >> 1) & 0x1);
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d_preamble <<= (b & 0x1);
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}
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for(uint8_t b : sync) {
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d_sync <<= (b >> 7);
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d_sync <<= ((b >> 6) & 0x1);
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d_sync <<= ((b >> 6) & 0x1);
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d_sync <<= ((b >> 5) & 0x1);
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d_sync <<= ((b >> 4) & 0x1);
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d_sync <<= ((b >> 3) & 0x1);
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d_sync <<= ((b >> 2) & 0x1);
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d_sync <<= ((b >> 1) & 0x1);
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d_sync <<= (b & 0x1);
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}
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/* Parameters checking */
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if (max_frame_len == 0) {
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throw std::invalid_argument (
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"The maximum frame size should be at least 1 byte");
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}
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if(d_sync_len < 8) {
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throw std::invalid_argument("SYNC word should be at least 8 bits");
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}
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if(d_preamble_len < 8) {
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throw std::invalid_argument("Preamble should be at least 8 bits");
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}
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if (d_preamble_len < 2 * d_preamble_thrsh) {
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throw std::invalid_argument (
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"Too many error bits are allowed for the preamble."
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"Consider lowering the threshold");
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}
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if (d_sync_len < 2 * d_sync_thrsh) {
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throw std::invalid_argument (
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"Too many error bits are allowed for the sync word. "
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"Consider lowering the threshold");
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}
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if (d_frame_size_field_len > 4) {
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throw std::invalid_argument ("Frame length field can be up to 4 bytes");
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}
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if (d_frame_size_field_len == 0) {
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throw std::invalid_argument ("Frame length field cannot be 0");
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}
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d_pdu = new uint8_t[max_frame_len];
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/* Register the PMT message queue */
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message_port_register_out(pmt::mp("out"));
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}
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/*
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* Our virtual destructor.
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*/
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frame_acquisition_impl::~frame_acquisition_impl ()
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{
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delete [] d_pdu;
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}
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int
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frame_acquisition_impl::work (int noutput_items,
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gr_vector_const_void_star &input_items,
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gr_vector_void_star &output_items)
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{
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const uint8_t *in = (const uint8_t *) input_items[0];
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switch(d_state)
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{
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case SEARCHING:
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return searching_preamble(in, noutput_items);
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case SEARCHING_SYNC:
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return searching_sync(in, noutput_items);
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case DECODING_GENERIC_FRAME_LEN:
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return dec_generic_frame_len(in, noutput_items);
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case DECODING_GOLAY24_FRAME_LEN:
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return dec_golay24_frame_len(in, noutput_items);
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case DECODING_PAYLOAD:
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return decoding(in, noutput_items);
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default:
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return noutput_items;
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}
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}
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int
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frame_acquisition_impl::searching_preamble (const uint8_t* in, int len)
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{
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for(int i = 0; i < len; i++) {
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d_preamble_shift_reg <<= in[i];
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shift_reg tmp = d_preamble_shift_reg ^ d_preamble;
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if(tmp.count() <= d_preamble_thrsh) {
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d_state = SEARCHING_SYNC;
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d_cnt = 0;
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return i+1;
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}
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}
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return len;
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}
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int
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frame_acquisition_impl::searching_sync (const uint8_t* in, int len)
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{
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for (int i = 0; i < len; i++) {
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d_sync_shift_reg <<= in[i];
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shift_reg tmp = d_sync_shift_reg ^ d_sync;
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d_cnt++;
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if (tmp.count () <= d_sync_thrsh) {
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switch(d_variant) {
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case GENERIC_VAR_FRAME_LEN:
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d_state = DECODING_GENERIC_FRAME_LEN;
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break;
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case GENERIC_CONSTANT_FRAME_LEN:
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d_state = DECODING_GENERIC_FRAME_LEN;
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break;
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}
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d_cnt = 0;
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return i + 1;
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}
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/* The sync word should be available by now */
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if(d_cnt > d_preamble_len * 2 + d_sync_len) {
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reset();
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return i + 1;
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}
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}
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return len;
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}
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int
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frame_acquisition_impl::dec_generic_frame_len (const uint8_t* in, int len)
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{
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const int s = std::min(len / 8, (int) d_frame_size_field_len);
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for(int i = 0; i < s; i++) {
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uint8_t b = 0x0;
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b |= in[i * 8] << 7;
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b |= in[i * 8 + 1] << 6;
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b |= in[i * 8 + 2] << 5;
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b |= in[i * 8 + 3] << 4;
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b |= in[i * 8 + 4] << 3;
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b |= in[i * 8 + 5] << 2;
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b |= in[i * 8 + 6] << 1;
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b |= in[i * 8 + 7];
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d_frame_len <<= 8;
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d_frame_len |= b;
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d_cnt++;
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if(d_cnt == d_frame_size_field_len) {
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/* Most of the available modems apply whitening on the frame length too */
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if(d_whitening) {
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uint32_t descrambled = 0x0;
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d_whitening->descramble((uint8_t *)&descrambled,
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(const uint8_t *)&d_frame_len,
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d_frame_size_field_len, true);
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d_frame_len = descrambled;
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}
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if(d_frame_len < d_max_frame_len) {
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d_state = DECODING_PAYLOAD;
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}
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else{
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reset();
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return (i + 1) * 8;
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}
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d_cnt = 0;
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return (i + 1) * 8;
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}
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}
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return s * 8;
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}
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int
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frame_acquisition_impl::dec_golay24_frame_len (const uint8_t* in, int len)
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{
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/* Golay24 needs 3 bytes to decode */
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const int s = std::min(len / 8, 3);
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for(int i = 0; i < s; i++) {
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uint8_t b = 0x0;
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b |= in[i * 8] << 7;
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b |= in[i * 8 + 1] << 6;
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b |= in[i * 8 + 2] << 5;
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b |= in[i * 8 + 3] << 4;
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b |= in[i * 8 + 4] << 3;
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b |= in[i * 8 + 5] << 2;
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b |= in[i * 8 + 6] << 1;
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b |= in[i * 8 + 7];
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d_frame_len <<= 8;
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d_frame_len |= b;
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d_cnt++;
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/* Try to decode the frame length */
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if (d_cnt == 3) {
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if(d_whitening) {
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uint32_t descrambled = 0x0;
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d_whitening->descramble((uint8_t *)&descrambled,
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(const uint8_t *)&d_frame_len, 3, true);
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d_frame_len = descrambled;
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}
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golay24 g = golay24 ();
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uint16_t tmp = 0;
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if (g.decode24 (&tmp, d_frame_len)) {
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d_frame_len = tmp;
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/* Check if the payload can fit in the buffer */
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if(d_frame_len > d_max_frame_len) {
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reset();
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return (i + 1) * 8;
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}
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else{
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d_state = DECODING_PAYLOAD;
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}
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}
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else {
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reset ();
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return (i + 1) * 8;
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}
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d_cnt = 0;
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return (i + 1) * 8;
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}
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}
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return s * 8;
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}
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int
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frame_acquisition_impl::decoding (const uint8_t* in, int len)
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{
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const int s = len / 8;
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for(int i = 0; i < s; i++) {
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uint8_t b = 0x0;
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b |= in[i * 8] << 7;
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b |= in[i * 8 + 1] << 6;
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b |= in[i * 8 + 2] << 5;
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b |= in[i * 8 + 3] << 4;
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b |= in[i * 8 + 4] << 3;
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b |= in[i * 8 + 5] << 2;
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b |= in[i * 8 + 6] << 1;
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b |= in[i * 8 + 7];
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d_pdu[d_cnt++] = b;
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if(d_cnt == d_frame_len) {
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if(d_whitening) {
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d_whitening->descramble(d_pdu, d_pdu, d_frame_len, true);
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}
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/* TODO */
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reset();
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return (i+1) * 8;
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}
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}
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return len;
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}
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void
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frame_acquisition_impl::reset ()
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{
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if(d_whitening) {
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d_whitening->reset();
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}
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d_cnt = 0;
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d_state = SEARCHING;
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d_preamble_shift_reg.reset();
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d_sync_shift_reg.reset();
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}
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} /* namespace satnogs */
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} /* namespace gr */
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