2016-06-30 22:39:16 +02:00
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/* -*- 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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2018-03-18 10:09:13 +01:00
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* Copyright (C) 2016,2018
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* Libre Space Foundation <http://librespacefoundation.org/>
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2016-06-30 22:39:16 +02:00
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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 "ax25_encoder_mb_impl.h"
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#include <satnogs/log.h>
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#include <satnogs/ax25.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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ax25_encoder_mb::sptr
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ax25_encoder_mb::make (const std::string& dest_addr, uint8_t dest_ssid,
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2018-03-18 10:09:13 +01:00
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const std::string& src_addr, uint8_t src_ssid,
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size_t preamble_len, size_t postamble_len,
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bool scramble)
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2016-06-30 22:39:16 +02:00
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{
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return gnuradio::get_initial_sptr (
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2018-03-18 10:09:13 +01:00
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new ax25_encoder_mb_impl (dest_addr, dest_ssid, src_addr, src_ssid,
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preamble_len, postamble_len, scramble));
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2016-06-30 22:39:16 +02:00
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}
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/*
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* The private constructor
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*/
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ax25_encoder_mb_impl::ax25_encoder_mb_impl (const std::string& dest_addr,
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2018-03-18 10:09:13 +01:00
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uint8_t dest_ssid,
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const std::string& src_addr,
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uint8_t src_ssid,
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size_t preamble_len,
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size_t postabmle_len,
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bool scramble) :
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gr::sync_block ("ax25_encoder_mb", gr::io_signature::make (0, 0, 0),
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gr::io_signature::make (1, 1, sizeof(uint8_t))),
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d_preamble_len (preamble_len),
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d_postamble_len (postabmle_len),
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d_scramble (scramble),
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d_remaining (0),
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d_produced (0),
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d_prev_bit (0x0),
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d_encoded_frame (
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new uint8_t[(preamble_len + postabmle_len
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+ (AX25_MAX_FRAME_LEN * 2)) * 8]),
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d_tmp_buf (
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new uint8_t[preamble_len + postabmle_len
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+ (AX25_MAX_FRAME_LEN * 2)]),
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d_addr_field (new uint8_t[AX25_MAX_ADDR_LEN]),
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d_lfsr (0x21, 0x0, 16)
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2016-06-30 22:39:16 +02:00
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{
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/* Input is a blob message containing the info field data */
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message_port_register_in (pmt::mp ("info"));
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d_addr_len = ax25_create_addr_field (d_addr_field, dest_addr, dest_ssid,
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src_addr, src_ssid);
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2016-06-30 22:39:16 +02:00
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}
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/*
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* Our virtual destructor.
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*/
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ax25_encoder_mb_impl::~ax25_encoder_mb_impl ()
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{
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delete [] d_encoded_frame;
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delete [] d_tmp_buf;
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delete [] d_addr_field;
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}
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int
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ax25_encoder_mb_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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2016-06-30 22:39:16 +02:00
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{
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const uint8_t *info;
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size_t info_len;
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size_t max_avail;
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size_t len;
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size_t i;
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pmt::pmt_t msg;
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ax25_encode_status_t status;
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uint8_t *out = (uint8_t *) output_items[0];
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/* If all the frame samples have already be sent, wait for a new frame */
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if (d_remaining == 0) {
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2018-03-18 10:09:13 +01:00
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d_produced = 0;
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d_prev_bit = 0x0;
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d_lfsr.reset ();
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/* Block waiting from a new message from users */
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msg = delete_head_blocking (pmt::mp ("info"));
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info = (const uint8_t *) pmt::blob_data (msg);
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info_len = pmt::blob_length (msg);
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/* Prepare and encode the AX.25 frame */
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len = ax25_prepare_frame (d_tmp_buf, info, info_len, AX25_I_FRAME,
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d_addr_field, d_addr_len, 0, 1,
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d_preamble_len, d_postamble_len);
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/* Perform bit stuffing */
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status = ax25_bit_stuffing (d_encoded_frame, &d_remaining, d_tmp_buf,
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len, d_preamble_len, d_postamble_len);
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if (status != AX25_ENC_OK) {
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LOG_ERROR("AX.25 encoding failed");
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d_remaining = 0;
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return 0;
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}
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/*Perform scrambling if the user asked for it */
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if (d_scramble) {
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for (i = 0; i < d_remaining; i++) {
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d_encoded_frame[i] = d_lfsr.next_bit_scramble (d_encoded_frame[i]);
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}
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/* Allow the LFSR to pop all its bits */
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d_remaining += 16;
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for (; i < d_remaining; i++) {
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d_encoded_frame[i] = d_lfsr.next_bit_scramble (0x0);
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}
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}
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/* Append a zero byte at the end */
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memset(&d_encoded_frame[d_remaining], 0, 8);
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d_remaining += 8;
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2016-06-30 22:39:16 +02:00
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}
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2018-03-18 10:09:13 +01:00
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/* If this is the first part of the frame add the start of burst tag*/
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if (d_produced == 0) {
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add_sob (nitems_written (0));
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}
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max_avail = std::min (d_remaining, (size_t) noutput_items);
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/* Perform NRZI encoding */
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for (i = 0; i < max_avail; i++) {
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out[i] = ((0x1 & ~d_encoded_frame[i + d_produced]) + d_prev_bit) % 2;
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d_prev_bit = out[i];
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}
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d_remaining -= max_avail;
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d_produced += max_avail;
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if (d_remaining == 0) {
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add_eob (nitems_written (0) + max_avail);
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}
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return (int) max_avail;
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2016-06-30 22:39:16 +02:00
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}
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void
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ax25_encoder_mb_impl::add_sob (uint64_t item)
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{
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static const pmt::pmt_t sob_key = pmt::string_to_symbol ("tx_sob");
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static const pmt::pmt_t value = pmt::PMT_T;
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static const pmt::pmt_t srcid = pmt::string_to_symbol (alias ());
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add_item_tag (0, item, sob_key, value, srcid);
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}
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void
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ax25_encoder_mb_impl::add_eob (uint64_t item)
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{
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static const pmt::pmt_t eob_key = pmt::string_to_symbol ("tx_eob");
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static const pmt::pmt_t value = pmt::PMT_T;
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static const pmt::pmt_t srcid = pmt::string_to_symbol (alias ());
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add_item_tag (0, item, eob_key, value, srcid);
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}
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} /* namespace satnogs */
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} /* namespace gr */
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