411 lines
13 KiB
C++
411 lines
13 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) 2016,2017,
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* 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 "upsat_fsk_frame_acquisition_impl.h"
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#include <satnogs/log.h>
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#include <satnogs/ax25.h>
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#include <satnogs/utils.h>
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#include <arpa/inet.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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upsat_fsk_frame_acquisition::sptr
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upsat_fsk_frame_acquisition::make (const std::vector<uint8_t> &preamble,
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const std::vector<uint8_t> &sync_word,
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bool whitening, bool manchester,
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bool check_crc, bool ax25_format,
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uint32_t whitening_mask,
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uint32_t whitening_seed,
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uint32_t whitening_order,
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size_t packet_len)
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{
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return gnuradio::get_initial_sptr (
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new upsat_fsk_frame_acquisition_impl (preamble, sync_word, whitening,
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manchester, check_crc,
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ax25_format, whitening_mask,
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whitening_seed,
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whitening_order,
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packet_len));
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}
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/*
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* The private constructor
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*/
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upsat_fsk_frame_acquisition_impl::upsat_fsk_frame_acquisition_impl (
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const std::vector<uint8_t> &preamble,
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const std::vector<uint8_t> &sync_word, bool whitening, bool manchester,
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bool check_crc, bool ax25_format, uint32_t whitening_mask,
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uint32_t whitening_seed, uint32_t whitening_order,
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size_t packet_len) :
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gr::sync_block ("upsat_fsk_frame_acquisition",
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gr::io_signature::make (1, 1, sizeof(float)),
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gr::io_signature::make (0, 0, 0)),
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d_preamble (preamble),
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d_preamble_len (preamble.size ()),
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d_sync_word (sync_word),
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d_sync_word_len (sync_word.size ()),
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/*
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* Preamble is used only for AGC. The true synchronization is
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* performed using the SYNC word. For this reason if some preamble
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* symbols are retrieved, the algorithm should immediately start
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* searching for the SYNC word.
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*/
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d_search_for_sync_thrhld (d_preamble_len / 3),
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d_whitening (whitening),
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d_manchester (manchester),
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d_check_crc (check_crc),
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d_is_ax25 (ax25_format),
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d_var_packet_len(packet_len == 0),
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d_state (SEARCHING),
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d_shifting_byte (0x0),
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d_decoded_bytes (0),
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d_decoded_bits (0),
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d_frame_len (0),
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d_descrambler (whitening_mask, whitening_seed, whitening_order)
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{
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size_t i;
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message_port_register_out (pmt::mp ("pdu"));
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if (d_preamble_len < 3) {
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throw std::invalid_argument ("Preamble must be at least 2 bytes long");
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}
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if (d_sync_word_len < 1) {
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throw std::invalid_argument (
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"Synchronization word must be at least 1 byte long");
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}
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for (i = 1; i < d_preamble_len; i++) {
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if (d_preamble[i] != d_preamble[0]) {
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throw std::invalid_argument (
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"The preamble should contain the same bytes");
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}
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}
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d_pdu = new uint8_t[UPSAT_MAX_FRAME_LEN];
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d_ax25_tmp_buf = new uint8_t[2 * UPSAT_MAX_FRAME_LEN * 8];
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d_ax25_buf = new uint8_t[2 * UPSAT_MAX_FRAME_LEN];
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/* If the fixed packet length is set, store the expected frame size */
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d_frame_len = packet_len;
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}
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/*
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* Our virtual destructor.
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*/
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upsat_fsk_frame_acquisition_impl::~upsat_fsk_frame_acquisition_impl ()
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{
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delete[] d_pdu;
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delete[] d_ax25_tmp_buf;
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delete[] d_ax25_buf;
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}
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inline void
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upsat_fsk_frame_acquisition_impl::slice_and_shift (float in)
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{
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uint8_t tmp;
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/* Slice the input into 0 and 1 bits */
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tmp = in > 0 ? 1 : 0;
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d_shifting_byte = d_shifting_byte << 1;
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d_shifting_byte |= tmp;
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}
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inline void
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upsat_fsk_frame_acquisition_impl::reset_state ()
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{
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LOG_DEBUG("Enter reset");
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d_state = SEARCHING;
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d_decoded_bytes = 0;
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d_decoded_bits = 0;
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d_shifting_byte = 0;
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}
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inline void
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upsat_fsk_frame_acquisition_impl::have_preamble ()
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{
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LOG_DEBUG("Enter have preamble");
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d_state = HAVE_PREAMBLE;
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d_decoded_bytes = 1;
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}
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inline void
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upsat_fsk_frame_acquisition_impl::searching_sync_word ()
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{
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LOG_DEBUG("Enter searching sync");
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d_state = SEARCHING_SYNC_WORD;
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d_decoded_bytes = 0;
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d_decoded_bits = 0;
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}
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inline void
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upsat_fsk_frame_acquisition_impl::have_sync ()
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{
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LOG_DEBUG("Enter have sync");
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d_state = HAVE_SYNC_WORD;
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/* The first SYNC byte have already been found */
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d_decoded_bytes = 1;
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d_decoded_bits = 0;
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}
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inline void
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upsat_fsk_frame_acquisition_impl::have_frame_len ()
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{
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LOG_DEBUG("Enter frame len");
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d_descrambler.reset ();
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d_state = HAVE_FRAME_LEN;
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d_decoded_bytes = 0;
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d_decoded_bits = 0;
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}
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inline void
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upsat_fsk_frame_acquisition_impl::have_payload ()
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{
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LOG_DEBUG("Enter have payload");
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d_state = HAVE_PAYLOAD;
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if(d_var_packet_len) {
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d_decoded_bytes = 1;
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}
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else {
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d_decoded_bytes = 0;
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}
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d_decoded_bits = 0;
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}
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inline void
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upsat_fsk_frame_acquisition_impl::unpack_ax25_bytes (size_t len_bytes)
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{
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size_t i;
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uint8_t *in = d_pdu + 1;
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for (i = 0; i < len_bytes; i++) {
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d_ax25_tmp_buf[8 * i] = (in[i] >> 7) & 0x1;
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d_ax25_tmp_buf[8 * i + 1] = (in[i] >> 6) & 0x1;
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d_ax25_tmp_buf[8 * i + 2] = (in[i] >> 5) & 0x1;
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d_ax25_tmp_buf[8 * i + 3] = (in[i] >> 4) & 0x1;
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d_ax25_tmp_buf[8 * i + 4] = (in[i] >> 3) & 0x1;
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d_ax25_tmp_buf[8 * i + 5] = (in[i] >> 2) & 0x1;
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d_ax25_tmp_buf[8 * i + 6] = (in[i] >> 1) & 0x1;
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d_ax25_tmp_buf[8 * i + 7] = in[i] & 0x1;
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}
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/* De-white the data if necessary */
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if (d_whitening) {
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d_descrambler.descramble_one_bit_per_byte (d_ax25_tmp_buf,
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d_ax25_tmp_buf,
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len_bytes * 8);
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}
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}
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int
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upsat_fsk_frame_acquisition_impl::work (
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int noutput_items, 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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int i;
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uint16_t crc_received;
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uint16_t crc_calc;
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size_t ax25_frame_len = 0;
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ax25_decode_status_t status;
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size_t payload_len;
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uint8_t *payload;
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const float *in = (const float *) input_items[0];
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for (i = 0; i < noutput_items; i++) {
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slice_and_shift (in[i]);
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switch (d_state)
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{
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case SEARCHING:
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if (d_shifting_byte == d_preamble[0]) {
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have_preamble ();
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}
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break;
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case HAVE_PREAMBLE:
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d_decoded_bits++;
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if (d_decoded_bits == 8) {
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d_decoded_bits = 0;
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if (d_shifting_byte == d_preamble[d_decoded_bytes]) {
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d_decoded_bytes++;
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if (d_decoded_bytes >= d_search_for_sync_thrhld) {
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/* End of the preamble. It's time for the sync word */
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searching_sync_word ();
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}
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}
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else {
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/* Reset the preamble detection */
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reset_state ();
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}
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}
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break;
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case SEARCHING_SYNC_WORD:
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d_decoded_bits++;
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if (d_shifting_byte == d_sync_word[0]) {
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have_sync ();
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break;
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}
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if (d_decoded_bits == 8) {
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d_decoded_bits = 0;
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d_decoded_bytes++;
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/*
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* If we decoded bytes have length greater than the preamble and
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* the SYNC word, we lost the frame...
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*/
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if (d_decoded_bytes
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> d_preamble_len - d_search_for_sync_thrhld
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+ d_sync_word_len) {
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reset_state ();
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}
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}
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break;
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case HAVE_SYNC_WORD:
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d_decoded_bits++;
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if (d_decoded_bits == 8) {
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d_decoded_bits = 0;
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if (d_shifting_byte == d_sync_word[d_decoded_bytes]) {
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d_decoded_bytes++;
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if (d_decoded_bytes == d_sync_word_len) {
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if(d_var_packet_len) {
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have_frame_len ();
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}
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else{
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have_payload();
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}
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}
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}
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else {
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reset_state ();
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}
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}
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break;
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case HAVE_FRAME_LEN:
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d_decoded_bits++;
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if (d_decoded_bits == 8) {
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/* Length field has been whitened if the option is enabled */
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if (d_whitening) {
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/* Frame length field is needed for the CRC calculation */
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d_descrambler.descramble (d_pdu, &d_shifting_byte, 1);
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/* CRC is not included in the frame length field, but we want it */
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d_frame_len = 1 + d_pdu[0] + sizeof(uint16_t);
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}
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else {
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/* Frame length field is needed for the CRC calculation */
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d_pdu[0] = d_shifting_byte;
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/* CRC is not included in the frame length field, but we want it */
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d_frame_len = 1 + d_shifting_byte + sizeof(uint16_t);
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}
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have_payload ();
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}
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break;
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case HAVE_PAYLOAD:
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d_decoded_bits++;
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if (d_decoded_bits == 8) {
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if(d_var_packet_len) {
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payload = d_pdu + 1;
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payload_len = d_frame_len - 1;
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}
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else{
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payload = d_pdu;
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payload_len = d_frame_len;
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}
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d_decoded_bits = 0;
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d_pdu[d_decoded_bytes] = d_shifting_byte;
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d_decoded_bytes++;
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if (d_decoded_bytes == d_frame_len) {
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if (d_is_ax25) {
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unpack_ax25_bytes (payload_len);
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status = ax25_decode (d_ax25_buf, &ax25_frame_len,
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d_ax25_tmp_buf, payload_len * 8);
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if (status == AX25_DEC_OK) {
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/* Skip the AX.25 header */
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message_port_pub (
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pmt::mp ("pdu"),
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pmt::make_blob (
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d_ax25_buf + AX25_MIN_ADDR_LEN + 2,
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ax25_frame_len - AX25_MIN_ADDR_LEN - 2));
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}
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/*
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* We are done here. Whitening and FSK CRC is not supported
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* when transmitting/receiving AX.25 frames
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*/
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reset_state ();
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break;
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}
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if (d_whitening) {
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d_descrambler.descramble (payload, payload, payload_len);
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}
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if (!d_check_crc) {
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message_port_pub (
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pmt::mp ("pdu"),
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pmt::make_blob (payload,
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payload_len - sizeof(uint16_t)));
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reset_state ();
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break;
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}
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/* Retrieve and check the CRC */
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memcpy (&crc_received, d_pdu + d_frame_len - sizeof(uint16_t),
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sizeof(uint16_t));
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/* The CRC is transmitted in network byte order */
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crc_received = ntohs (crc_received);
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crc_calc = crc16_ccitt (d_pdu, d_frame_len - sizeof(uint16_t));
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if (crc_calc == crc_received) {
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message_port_pub (
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pmt::mp ("pdu"),
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pmt::make_blob (payload,
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payload_len - sizeof(uint16_t)));
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}
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else {
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LOG_WARN("Frame with wrong CRC got 0x%x calc 0x%x",
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crc_received, crc_calc);
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}
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reset_state ();
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}
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}
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break;
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default:
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LOG_WARN("Unknown decoding state");
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}
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}
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return noutput_items;
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}
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} /* namespace satnogs */
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} /* namespace gr */
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