| /* -*- 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 <grgsm/endian.h> |
| #include <boost/algorithm/clamp.hpp> |
| #include "cx_channel_hopper_impl.h" |
| |
| namespace gr { |
| namespace gsm { |
| |
| cx_channel_hopper::sptr |
| cx_channel_hopper::make(const std::vector<int> &ma, int maio, int hsn) |
| { |
| return gnuradio::get_initial_sptr |
| (new cx_channel_hopper_impl(ma, maio, hsn)); |
| } |
| |
| /* |
| * The private constructor |
| */ |
| cx_channel_hopper_impl::cx_channel_hopper_impl(const std::vector<int> &ma, int maio, int hsn) |
| : gr::block("cx_channel_hopper", |
| gr::io_signature::make(0, 0, 0), |
| gr::io_signature::make(0, 0, 0)), |
| d_ma(ma), |
| d_maio(maio), |
| d_hsn(hsn) |
| { |
| d_narfcn = ma.size(); |
| |
| // Check user input for GSM 05.02, p16 compliance |
| if(d_narfcn < 1 || d_narfcn > 64) { |
| std::cerr << "warning: clamping number of RFCNs in the MA (" << d_narfcn << "), which should be 1 <= N <= 64." << std::endl; |
| d_narfcn = boost::algorithm::clamp(d_narfcn, 1, 64); |
| d_ma.resize(d_narfcn); |
| } |
| |
| if(d_maio < 0 || d_maio >= d_narfcn) { |
| std::cerr << "warning: clamping MAIO (" << d_maio << "), which should be 0 <= MAIO < N." << std::endl; |
| d_maio = boost::algorithm::clamp(d_maio, 0, d_narfcn - 1); |
| } |
| |
| if(d_hsn < 0 || d_hsn > 63) { |
| std::cerr << "warning: clamping HSN (" << d_hsn << "), which should be 0 <= HSN < 64." << std::endl; |
| d_hsn = boost::algorithm::clamp(d_hsn, 0, 63); |
| } |
| |
| message_port_register_in(pmt::mp("CX")); |
| set_msg_handler(pmt::mp("CX"), boost::bind(&cx_channel_hopper_impl::assemble_bursts, this, _1)); |
| message_port_register_out(pmt::mp("bursts")); |
| } |
| |
| /* |
| * Our virtual destructor. |
| */ |
| cx_channel_hopper_impl::~cx_channel_hopper_impl() |
| { |
| } |
| |
| /** |
| * Random number table used for calculating the |
| * hopping sequence. Defined in GSM 05.02. |
| */ |
| unsigned char RNTABLE[114] = { |
| 48, 98, 63, 1, 36, 95, 78, 102, 94, 73, \ |
| 0, 64, 25, 81, 76, 59, 124, 23, 104, 100, \ |
| 101, 47, 118, 85, 18, 56, 96, 86, 54, 2, \ |
| 80, 34, 127, 13, 6, 89, 57, 103, 12, 74, \ |
| 55, 111, 75, 38, 109, 71, 112, 29, 11, 88, \ |
| 87, 19, 3, 68, 110, 26, 33, 31, 8, 45, \ |
| 82, 58, 40, 107, 32, 5, 106, 92, 62, 67, \ |
| 77, 108, 122, 37, 60, 66, 121, 42, 51, 126, \ |
| 117, 114, 4, 90, 43, 52, 53, 113, 120, 72, \ |
| 16, 49, 7, 79, 119, 61, 22, 84, 9, 97, \ |
| 91, 15, 21, 24, 46, 39, 93, 105, 65, 70, \ |
| 125, 99, 17, 123 \ |
| }; |
| |
| /* |
| * Slow Frequency Hopping (SFH) MAI calculation based |
| * on airprobe-hopping by Bogdan Diaconescu. |
| */ |
| int cx_channel_hopper_impl::calculate_ma_sfh(int maio, int hsn, int n, int fn) |
| { |
| int mai = 0; |
| int s = 0; |
| int nbin = floor(log2(n) + 1); |
| int t1 = fn / 1326; |
| int t2 = fn % 26; |
| int t3 = fn % 51; |
| |
| if (hsn == 0) |
| mai = (fn + maio) % n; |
| else { |
| int t1r = t1 % 64; |
| int m = t2 + RNTABLE[(hsn ^ t1r) + t3]; |
| int mprim = m % (1 << nbin); |
| int tprim = t3 % (1 << nbin); |
| |
| if (mprim < n) |
| s = mprim; |
| else |
| s = (mprim + tprim) % n; |
| |
| mai = (s + maio) % n; |
| } |
| |
| return (mai); |
| } |
| |
| /** |
| * Given MA, MAIO, HSN, and FN, decide which frames |
| * to forward to the demapper. |
| */ |
| void cx_channel_hopper_impl::assemble_bursts(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); |
| uint16_t frame_ca = be16toh(header->arfcn); |
| int mai = calculate_ma_sfh(d_maio, d_hsn, d_narfcn, frame_nr); |
| |
| if(d_ma[mai] == (int)frame_ca) { |
| message_port_pub(pmt::mp("bursts"), msg); |
| } |
| } |
| |
| } /* namespace gsm */ |
| } /* namespace gr */ |