| /* -*- 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 <grgsm/gsmtap.h> |
| #include "control_channels_decoder_impl.h" |
| |
| #define DATA_BYTES 23 |
| |
| namespace gr { |
| namespace gsm { |
| |
| 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) |
| { |
| //initialize de/interleaver |
| int j, k, B; |
| for (k = 0; k < CONV_SIZE; k++) |
| { |
| B = k % 4; |
| j = 2 * ((49 * k) % 57) + ((k % 8) / 4); |
| interleave_trans[k] = B * 114 + j; //114=57 + 57 |
| } |
| |
| //initialize decoder |
| FC_init(&fc_ctx, 40, 184); |
| |
| //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) |
| { |
| unsigned char iBLOCK[BLOCKS*iBLOCK_SIZE], hl, hn, conv_data[CONV_SIZE], decoded_data[PARITY_OUTPUT_SIZE]; |
| 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 |
| 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); |
| |
| for(int jj = 0; jj < 57; jj++) |
| { |
| iBLOCK[ii*iBLOCK_SIZE+jj] = burst_bits[jj + 3]; |
| iBLOCK[ii*iBLOCK_SIZE+jj+57] = burst_bits[jj + 88]; //88 = 3+57+1+26+1 |
| } |
| } |
| //deinterleave |
| for (int k = 0; k < CONV_SIZE; k++) |
| { |
| conv_data[k] = iBLOCK[interleave_trans[k]]; |
| } |
| //convolutional code decode |
| int errors = conv_decode(decoded_data, conv_data); |
| //std::cout << "Errors:" << errors << " " << parity_check(decoded_data) << std::endl; |
| // check parity |
| // If parity check error detected try to fix it. |
| |
| if (parity_check(decoded_data)) |
| { |
| FC_init(&fc_ctx, 40, 184); |
| unsigned char crc_result[PARITY_OUTPUT_SIZE]; |
| if (FC_check_crc(&fc_ctx, decoded_data, crc_result) == 0) |
| { |
| //("error: sacch: parity error (errors=%d fn=%d)\n", errors, ctx->fn); |
| //std::cout << "Uncorrectable errors!" << std::endl; |
| errors = -1; |
| return; |
| } else { |
| //DEBUGF("Successfully corrected parity bits! (errors=%d fn=%d)\n", errors, ctx->fn); |
| //std::cout << "Corrected some errors" << std::endl; |
| memcpy(decoded_data, crc_result, PARITY_OUTPUT_SIZE); |
| errors = 0; |
| } |
| } else { |
| //std::cout << "Everything correct" << std::endl; |
| } |
| //compress bits |
| unsigned char outmsg[27]; |
| unsigned char sbuf_len=224; |
| int i, j, c, pos=0; |
| for(i = 0; i < sbuf_len; i += 8) { |
| for(j = 0, c = 0; (j < 8) && (i + j < sbuf_len); j++){ |
| c |= (!!decoded_data[i + j]) << j; |
| } |
| outmsg[pos++] = c & 0xff; |
| } |
| |
| //send message with header of the first burst |
| pmt::pmt_t first_header_plus_burst = pmt::cdr(d_bursts[0]); |
| gsmtap_hdr * header = (gsmtap_hdr *)pmt::blob_data(first_header_plus_burst); |
| header->type = GSMTAP_TYPE_UM; |
| |
| int8_t * header_content = (int8_t *)header; |
| |
| int8_t header_plus_data[sizeof(gsmtap_hdr)+DATA_BYTES]; |
| memcpy(header_plus_data, header_content, sizeof(gsmtap_hdr)); |
| memcpy(header_plus_data+sizeof(gsmtap_hdr), outmsg, DATA_BYTES); |
| |
| pmt::pmt_t msg_binary_blob = pmt::make_blob(header_plus_data,DATA_BYTES+sizeof(gsmtap_hdr)); |
| pmt::pmt_t msg_out = pmt::cons(pmt::PMT_NIL, msg_binary_blob); |
| |
| message_port_pub(pmt::mp("msgs"), msg_out); |
| } |
| return; |
| } |
| } /* namespace gsm */ |
| } /* namespace gr */ |
| |