| /* -*- c++ -*- */ |
| /* |
| * @file |
| * @author 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 "tch_f_chans_demapper_impl.h" |
| #include <grgsm/endian.h> |
| #include <grgsm/gsmtap.h> |
| |
| namespace gr { |
| namespace gsm { |
| |
| tch_f_chans_demapper::sptr |
| tch_f_chans_demapper::make(unsigned int timeslot_nr) |
| { |
| return gnuradio::get_initial_sptr |
| (new tch_f_chans_demapper_impl(timeslot_nr)); |
| } |
| |
| /* |
| * The private constructor |
| * |
| */ |
| tch_f_chans_demapper_impl::tch_f_chans_demapper_impl(unsigned int timeslot_nr) |
| : gr::block("tch_f_chans_demapper", |
| gr::io_signature::make(0, 0, 0), |
| gr::io_signature::make(0, 0, 0)), |
| d_timeslot(timeslot_nr) |
| |
| { |
| for(int ii=0; ii<13; ii++) |
| { |
| int startpos = ((int)(ii / 4) * 4); |
| d_starts_fn_mod26[ii] = startpos; |
| d_starts_fn_mod26[ii + 13] = startpos + 13; |
| } |
| |
| d_bursts_stolen = false; |
| |
| message_port_register_in(pmt::mp("bursts")); |
| set_msg_handler(pmt::mp("bursts"), boost::bind(&tch_f_chans_demapper_impl::filter_tch_chans, this, _1)); |
| message_port_register_out(pmt::mp("tch_bursts")); |
| message_port_register_out(pmt::mp("acch_bursts")); |
| } |
| |
| /* |
| * Our virtual destructor. |
| */ |
| tch_f_chans_demapper_impl::~tch_f_chans_demapper_impl() |
| { |
| } |
| |
| void tch_f_chans_demapper_impl::filter_tch_chans(pmt::pmt_t msg) |
| { |
| pmt::pmt_t header_plus_burst = pmt::cdr(msg); |
| gsmtap_hdr * header = (gsmtap_hdr *)pmt::blob_data(header_plus_burst); |
| |
| uint32_t frame_nr = be32toh(header->frame_number); |
| uint32_t fn_mod26 = frame_nr % 26; |
| uint32_t fn26_start = d_starts_fn_mod26[fn_mod26]; |
| uint32_t fn26_stop = fn26_start + 3; |
| int8_t * burst_bits = (int8_t *)(pmt::blob_data(header_plus_burst))+sizeof(gsmtap_hdr); |
| |
| if(header->timeslot == d_timeslot){ |
| header->sub_type = GSMTAP_CHANNEL_TCH_F; |
| |
| if (fn_mod26 == 12 || fn_mod26 == 25) |
| { |
| header->sub_type = GSMTAP_CHANNEL_ACCH|GSMTAP_CHANNEL_TCH_F; |
| |
| // position of SACCH burst based on timeslot |
| // see specification gsm 05.02 |
| uint32_t index; |
| bool is_sacch = false; |
| |
| if (d_timeslot % 2 == 0 && fn_mod26 == 12) |
| { |
| index = (((frame_nr - 12) / 26) - (d_timeslot / 2)) % 4; |
| is_sacch = true; |
| } |
| else if (d_timeslot % 2 == 1 && fn_mod26 == 25) |
| { |
| index = (((frame_nr - 25) / 26) - ((d_timeslot - 1) / 2)) % 4; |
| is_sacch = true; |
| } |
| |
| if (is_sacch) |
| { |
| d_bursts_sacch[index] = msg; |
| d_frame_numbers_sacch[index] = frame_nr; |
| |
| if (index == 3) |
| { |
| //check for a situation where some bursts were lost |
| //in this situation frame numbers won't be consecutive |
| bool frames_are_consecutive = true; |
| for(int jj=1; jj<4; jj++) |
| { |
| if((d_frame_numbers_sacch[jj]-d_frame_numbers_sacch[jj-1]) != 26) |
| { |
| frames_are_consecutive = false; |
| } |
| } |
| if(frames_are_consecutive) |
| { |
| //send bursts to the output |
| for(int jj=0; jj<4; jj++) |
| { |
| message_port_pub(pmt::mp("acch_bursts"), d_bursts_sacch[jj]); |
| } |
| } |
| } |
| } |
| } |
| else |
| { |
| if(fn_mod26>=fn26_start && fn_mod26<=fn26_stop) |
| { |
| uint32_t ii = fn_mod26 - fn26_start; |
| d_frame_numbers[ii] = frame_nr; |
| d_bursts[ii] = msg; |
| |
| // check if stealing bits are set |
| // see gsm 05.03 |
| if (static_cast<int>(burst_bits[60]) == 1 && static_cast<int>(burst_bits[87]) == 1) |
| { |
| d_bursts_stolen = true; |
| } |
| } |
| |
| if(fn_mod26==fn26_stop) |
| { |
| //check for a situation where some bursts were lost |
| //in this situation frame numbers won't be consecutive |
| bool frames_are_consecutive = true; |
| |
| for(int jj=1; jj<4; jj++) |
| { |
| if((d_frame_numbers[jj]-d_frame_numbers[jj-1])!=1) |
| { |
| frames_are_consecutive = false; |
| } |
| } |
| if(frames_are_consecutive) |
| { |
| //send bursts to the output |
| for(int jj=0; jj<4; jj++) |
| { |
| if (d_bursts_stolen) |
| { |
| message_port_pub(pmt::mp("acch_bursts"), d_bursts[jj]); |
| } |
| else |
| { |
| message_port_pub(pmt::mp("tch_bursts"), d_bursts[jj]); |
| } |
| } |
| d_bursts_stolen = false; |
| } |
| } |
| } |
| } |
| } |
| } /* namespace gsm */ |
| } /* namespace gr */ |
| |