| /* -*- c++ -*- */ |
| /* |
| * @file |
| * @author (C) 2014 by Piotr Krysik <ptrkrysik@gmail.com> |
| * @section LICENSE |
| * |
| * Gr-gsm is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License as published by |
| * the Free Software Foundation; either version 3, or (at your option) |
| * any later version. |
| * |
| * Gr-gsm is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * GNU General Public License for more details. |
| * |
| * You should have received a copy of the GNU General Public License |
| * along with gr-gsm; see the file COPYING. If not, write to |
| * the Free Software Foundation, Inc., 51 Franklin Street, |
| * Boston, MA 02110-1301, USA. |
| */ |
| |
| #ifdef HAVE_CONFIG_H |
| #include "config.h" |
| #endif |
| |
| #include <gnuradio/io_signature.h> |
| #include <grgsm/gsmtap.h> |
| #include "control_channels_decoder_impl.h" |
| |
| #define DATA_BYTES 23 |
| |
| namespace gr { |
| namespace gsm { |
| |
| static int ubits2sbits(ubit_t *ubits, sbit_t *sbits, int count) |
| { |
| int i; |
| |
| for (i = 0; i < count; i++) { |
| if (*ubits == 0x23) { |
| ubits++; |
| sbits++; |
| continue; |
| } |
| if ((*ubits++) & 1) |
| *sbits++ = -127; |
| else |
| *sbits++ = 127; |
| } |
| |
| return count; |
| } |
| |
| control_channels_decoder::sptr |
| control_channels_decoder::make() |
| { |
| return gnuradio::get_initial_sptr |
| (new control_channels_decoder_impl()); |
| } |
| |
| /* |
| * Constructor |
| */ |
| control_channels_decoder_impl::control_channels_decoder_impl() |
| : gr::block("control_channels_decoder", |
| gr::io_signature::make(0, 0, 0), |
| gr::io_signature::make(0, 0, 0)), |
| d_collected_bursts_num(0) |
| { |
| //setup input/output ports |
| message_port_register_in(pmt::mp("bursts")); |
| set_msg_handler(pmt::mp("bursts"), boost::bind(&control_channels_decoder_impl::decode, this, _1)); |
| message_port_register_out(pmt::mp("msgs")); |
| } |
| |
| control_channels_decoder_impl::~control_channels_decoder_impl() |
| { |
| } |
| |
| void control_channels_decoder_impl::decode(pmt::pmt_t msg) |
| { |
| ubit_t bursts_u[116 * 4]; |
| sbit_t bursts_s[116 * 4]; |
| uint8_t result[23]; |
| int n_errors, n_bits_total; |
| int8_t header_plus_data[sizeof(gsmtap_hdr)+DATA_BYTES]; |
| |
| d_bursts[d_collected_bursts_num] = msg; |
| d_collected_bursts_num++; |
| |
| //get convecutive bursts |
| if(d_collected_bursts_num==4) |
| { |
| d_collected_bursts_num=0; |
| //reorganize data from input bursts |
| for(int ii = 0; ii < 4; ii++) |
| { |
| pmt::pmt_t header_plus_burst = pmt::cdr(d_bursts[ii]); |
| int8_t * burst_bits = (int8_t *)(pmt::blob_data(header_plus_burst))+sizeof(gsmtap_hdr); |
| |
| memcpy(&bursts_u[ii*116], &burst_bits[3],58); |
| memcpy(&bursts_u[ii*116+58], &burst_bits[3+57+1+26],58); |
| } |
| //convert to soft bits |
| ubits2sbits(bursts_u, bursts_s, 116 * 4); |
| //decode |
| gsm0503_xcch_decode(result, bursts_s, &n_errors, &n_bits_total); |
| |
| //extract header of the first burst of the four bursts |
| pmt::pmt_t first_header_plus_burst = pmt::cdr(d_bursts[0]); |
| gsmtap_hdr * header = (gsmtap_hdr *)pmt::blob_data(first_header_plus_burst); |
| //copy header and data |
| memcpy(header_plus_data, header, sizeof(gsmtap_hdr)); |
| memcpy(header_plus_data+sizeof(gsmtap_hdr), result, DATA_BYTES); |
| //set data type in the header |
| ((gsmtap_hdr*)header_plus_data)->type = GSMTAP_TYPE_UM; |
| //prepare message |
| pmt::pmt_t msg_out = pmt::cons(pmt::PMT_NIL, pmt::make_blob(header_plus_data,DATA_BYTES+sizeof(gsmtap_hdr))); |
| //send message to the output |
| message_port_pub(pmt::mp("msgs"), msg_out); |
| } |
| return; |
| } |
| } /* namespace gsm */ |
| } /* namespace gr */ |
| |