piotr | faacc72 | 2014-07-20 23:48:32 +0200 | [diff] [blame] | 1 | /* -*- c++ -*- */ |
| 2 | /* |
| 3 | * Copyright 2014 <+YOU OR YOUR COMPANY+>. |
| 4 | * |
| 5 | * This is free software; you can redistribute it and/or modify |
| 6 | * it under the terms of the GNU General Public License as published by |
| 7 | * the Free Software Foundation; either version 3, or (at your option) |
| 8 | * any later version. |
| 9 | * |
| 10 | * This software is distributed in the hope that it will be useful, |
| 11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 13 | * GNU General Public License for more details. |
| 14 | * |
| 15 | * You should have received a copy of the GNU General Public License |
| 16 | * along with this software; see the file COPYING. If not, write to |
| 17 | * the Free Software Foundation, Inc., 51 Franklin Street, |
| 18 | * Boston, MA 02110-1301, USA. |
| 19 | */ |
| 20 | |
| 21 | #ifdef HAVE_CONFIG_H |
| 22 | #include "config.h" |
| 23 | #endif |
| 24 | |
| 25 | #include <gnuradio/io_signature.h> |
| 26 | #include <gsm/gsmtap.h> |
| 27 | #include "control_channels_decoder_impl.h" |
| 28 | |
| 29 | namespace gr { |
| 30 | namespace gsm { |
| 31 | |
| 32 | control_channels_decoder::sptr |
| 33 | control_channels_decoder::make() |
| 34 | { |
| 35 | return gnuradio::get_initial_sptr |
| 36 | (new control_channels_decoder_impl()); |
| 37 | } |
| 38 | |
| 39 | /* |
| 40 | * The private constructor |
| 41 | */ |
| 42 | control_channels_decoder_impl::control_channels_decoder_impl() |
| 43 | : gr::block("control_channels_decoder", |
| 44 | gr::io_signature::make(0, 0, 0), |
| 45 | gr::io_signature::make(0, 0, 0)), |
| 46 | d_collected_bursts_num(0) |
| 47 | { |
| 48 | //initialize de/interleaver |
| 49 | int j, k, B; |
| 50 | for (k = 0; k < CONV_SIZE; k++) |
| 51 | { |
| 52 | B = k % 4; |
| 53 | j = 2 * ((49 * k) % 57) + ((k % 8) / 4); |
| 54 | interleave_trans[k] = B * 114 + j; //114=57 + 57 |
| 55 | } |
| 56 | |
| 57 | FC_init(&fc_ctx, 40, 184); |
| 58 | message_port_register_in(pmt::mp("bursts")); |
| 59 | set_msg_handler(pmt::mp("bursts"), boost::bind(&control_channels_decoder_impl::decode, this, _1)); |
| 60 | // message_port_register_out(pmt::mp("")); |
| 61 | } |
| 62 | |
| 63 | /* |
| 64 | * Our virtual destructor. |
| 65 | */ |
| 66 | control_channels_decoder_impl::~control_channels_decoder_impl() |
| 67 | { |
| 68 | } |
| 69 | |
| 70 | void control_channels_decoder_impl::decode(pmt::pmt_t msg) |
| 71 | { |
| 72 | unsigned char iBLOCK[BLOCKS*iBLOCK_SIZE], hl, hn, conv_data[CONV_SIZE], decoded_data[PARITY_OUTPUT_SIZE]; |
| 73 | d_bursts[d_collected_bursts_num] = msg; |
| 74 | d_collected_bursts_num++; |
| 75 | //get convecutive bursts |
| 76 | pmt::pmt_t header_blob = pmt::car(msg); |
| 77 | gsmtap_hdr * header = (gsmtap_hdr *)pmt::blob_data(header_blob); |
| 78 | |
| 79 | if(d_collected_bursts_num==4) |
| 80 | { |
| 81 | d_collected_bursts_num=0; |
| 82 | //reorganize data |
| 83 | for(int ii = 0; ii < 4; ii++) |
| 84 | { |
| 85 | pmt::pmt_t burst_content = pmt::cdr(d_bursts[ii]); |
| 86 | int8_t * burst_bits = (int8_t *)pmt::blob_data(burst_content); |
| 87 | |
| 88 | for(int jj = 0; jj < 57; jj++) |
| 89 | { |
| 90 | iBLOCK[ii*iBLOCK_SIZE+jj] = burst_bits[jj + 3]; |
| 91 | iBLOCK[ii*iBLOCK_SIZE+jj+57] = burst_bits[jj + 88]; //88 = 3+57+1+26+1 |
| 92 | } |
| 93 | } |
| 94 | //deinterleave |
| 95 | for (int k = 0; k < CONV_SIZE; k++) |
| 96 | { |
| 97 | conv_data[k] = iBLOCK[interleave_trans[k]]; |
| 98 | } |
| 99 | //convolutional code decode |
| 100 | int errors = conv_decode(decoded_data, conv_data); |
| 101 | //std::cout << "Errors:" << errors << " " << parity_check(decoded_data) << std::endl; |
| 102 | // check parity |
| 103 | // If parity check error detected try to fix it. |
| 104 | |
| 105 | if (parity_check(decoded_data)) |
| 106 | { |
| 107 | FC_init(&fc_ctx, 40, 184); |
| 108 | unsigned char crc_result[PARITY_OUTPUT_SIZE]; |
| 109 | if (FC_check_crc(&fc_ctx, decoded_data, crc_result) == 0) |
| 110 | { |
| 111 | //("error: sacch: parity error (errors=%d fn=%d)\n", errors, ctx->fn); |
| 112 | //std::cout << "Uncorrectable errors!" << std::endl; |
| 113 | errors = -1; |
| 114 | } else { |
| 115 | //DEBUGF("Successfully corrected parity bits! (errors=%d fn=%d)\n", errors, ctx->fn); |
| 116 | //std::cout << "Corrected some errors" << std::endl; |
| 117 | memcpy(decoded_data, crc_result, PARITY_OUTPUT_SIZE); |
| 118 | errors = 0; |
| 119 | } |
| 120 | } else { |
| 121 | //std::cout << "Everything correct" << std::endl; |
| 122 | } |
| 123 | //compress bits |
| 124 | unsigned char outmsg[27]; |
| 125 | unsigned char sbuf_len=224; |
| 126 | int i, j, c, pos=0; |
| 127 | for(i = 0; i < sbuf_len; i += 8) { |
| 128 | for(j = 0, c = 0; (j < 8) && (i + j < sbuf_len); j++){ |
| 129 | c |= (!!decoded_data[i + j]) << j; |
| 130 | } |
| 131 | outmsg[pos++] = c & 0xff; |
| 132 | } |
| 133 | |
| 134 | //printf("%6d %d:", (0 + 1), 0); |
| 135 | int jj=0; |
| 136 | while (jj < 23){ |
| 137 | printf(" %02x", outmsg[jj]);//decoded_data[jj]); |
| 138 | jj++; |
| 139 | } |
| 140 | printf("\n"); |
| 141 | fflush(stdout); |
| 142 | } |
| 143 | return; |
| 144 | } |
| 145 | } /* namespace gsm */ |
| 146 | } /* namespace gr */ |
| 147 | |