diff options
Diffstat (limited to 'lib/decoding/control_channels_decoder_impl.cc')
| -rw-r--r-- | lib/decoding/control_channels_decoder_impl.cc | 109 |
1 files changed, 41 insertions, 68 deletions
diff --git a/lib/decoding/control_channels_decoder_impl.cc b/lib/decoding/control_channels_decoder_impl.cc index 532e255..a6abaa3 100644 --- a/lib/decoding/control_channels_decoder_impl.cc +++ b/lib/decoding/control_channels_decoder_impl.cc @@ -1,7 +1,7 @@ /* -*- c++ -*- */ /* * @file - * @author Piotr Krysik <ptrkrysik@gmail.com> + * @author (C) 2014 by Piotr Krysik <ptrkrysik@gmail.com> * @section LICENSE * * Gr-gsm is free software; you can redistribute it and/or modify @@ -33,6 +33,25 @@ 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() { @@ -49,18 +68,6 @@ namespace gr { 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)); @@ -73,78 +80,44 @@ namespace gr { 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]; + 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 + //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); - 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]]; + memcpy(&bursts_u[ii*116], &burst_bits[3],58); + memcpy(&bursts_u[ii*116+58], &burst_bits[3+57+1+26],58); } - //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. + //convert to soft bits + ubits2sbits(bursts_u, bursts_s, 116 * 4); + //decode + gsm0503_xcch_decode(result, bursts_s, &n_errors, &n_bits_total); - 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[28]; - 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 + //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); - int8_t header_plus_data[sizeof(gsmtap_hdr)+DATA_BYTES]; + //copy header and data memcpy(header_plus_data, header, sizeof(gsmtap_hdr)); - memcpy(header_plus_data+sizeof(gsmtap_hdr), outmsg, DATA_BYTES); + 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; - - 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); - + //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; |