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/* -*- c++ -*- */
/*
* @file
* @author Roman Khassraf <rkhassraf@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>
#define BURST_SIZE 148
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<3; ii++)
// {
// d_bursts_stolen[ii] = 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 fn_mod13 = frame_nr % 13;
int8_t * burst_bits = (int8_t *)(pmt::blob_data(header_plus_burst))+sizeof(gsmtap_hdr);
if(header->timeslot == d_timeslot){
int8_t new_msg[sizeof(gsmtap_hdr)+BURST_SIZE];
gsmtap_hdr * new_hdr = (gsmtap_hdr*)new_msg;
memcpy(new_msg, header, sizeof(gsmtap_hdr)+BURST_SIZE);
new_hdr->sub_type = GSMTAP_CHANNEL_TCH_F;
if (fn_mod13 == 12)
new_hdr->sub_type = GSMTAP_CHANNEL_ACCH|GSMTAP_CHANNEL_TCH_F;
pmt::pmt_t msg_binary_blob = pmt::make_blob(new_msg,sizeof(gsmtap_hdr)+BURST_SIZE);
pmt::pmt_t msg_out = pmt::cons(pmt::PMT_NIL, msg_binary_blob);
//distinguishing uplink and downlink bursts
bool uplink_burst = (be16toh(header->arfcn) & 0x4000) ? true : false;
if(uplink_burst)
{
sacch_tch_demapper(fn_mod13, fn_mod26, frame_nr,d_bursts_sacch_ul,
d_frame_numbers_sacch_ul, d_bursts_ul, d_frame_numbers_ul, msg_out);
}
else
{
sacch_tch_demapper(fn_mod13, fn_mod26, frame_nr,d_bursts_sacch_dl,
d_frame_numbers_sacch_dl, d_bursts_dl, d_frame_numbers_dl, msg_out);
}
}
}
void tch_f_chans_demapper_impl::sacch_tch_demapper(uint32_t fn_mod13, u_int32_t fn_mod26, uint32_t frame_nr,
pmt::pmt_t *d_bursts_sacch,
uint32_t *d_frame_numbers_sacch, pmt::pmt_t d_bursts[3][8],
uint32_t d_frame_numbers[3][8], pmt::pmt_t msg_out)
{
bool frames_are_consecutive = true;
if (fn_mod13 == 12)
{
// 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_out;
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
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_mod13 <= 3)
{
// add to b1 and b3
d_bursts[0][fn_mod13] = msg_out;
d_bursts[2][fn_mod13 + 4] = msg_out;
// set framenumber for later checking of continuity
d_frame_numbers[0][fn_mod13] = frame_nr;
d_frame_numbers[2][fn_mod13 + 4] = frame_nr;
}
else if (fn_mod13 >= 4 && fn_mod13 <= 7)
{
// add to b1 and b2
d_bursts[0][fn_mod13] = msg_out;
d_bursts[1][fn_mod13 - 4] = msg_out;
// set framenumber for later checking of continuity
d_frame_numbers[0][fn_mod13] = frame_nr;
d_frame_numbers[1][fn_mod13 - 4] = frame_nr;
}
else if (fn_mod13 >= 8 && fn_mod13 <= 11)
{
// add to b2 and b3
d_bursts[1][fn_mod13 - 4] = msg_out;
d_bursts[2][fn_mod13 - 8] = msg_out;
// set framenumber for later checking of continuity
d_frame_numbers[1][fn_mod13 - 4] = frame_nr;
d_frame_numbers[2][fn_mod13 - 8] = frame_nr;
}
// send burst 1 or burst 2 to output
if (fn_mod13 == 3 || fn_mod13 == 7 || fn_mod13 == 11)
{
int tch_burst_nr = 0;
if (fn_mod13 == 11)
{
tch_burst_nr = 1;
}
else if (fn_mod13 == 3)
{
tch_burst_nr = 2;
}
//check for a situation where some bursts were lost
//in this situation frame numbers won't be consecutive
frames_are_consecutive = true;
for(int jj=1; jj<8; jj++)
{
if (((d_frame_numbers[tch_burst_nr][jj] - d_frame_numbers[tch_burst_nr][jj-1]) != 1) && frames_are_consecutive)
{
frames_are_consecutive = false;
// burst 3 has 1 sacch burst in between
if (tch_burst_nr == 2 && jj == 4
&& d_frame_numbers[tch_burst_nr][jj] - d_frame_numbers[tch_burst_nr][jj - 1] == 2)
{
frames_are_consecutive = true;
}
}
}
if(frames_are_consecutive)
{
//send bursts to the output
for(int jj=0; jj<8; jj++)
{
message_port_pub(pmt::mp("tch_bursts"), d_bursts[tch_burst_nr][jj]);
}
// useless
// d_bursts_stolen[tch_burst_nr] = false;
}
}
}
}
} /* namespace gsm */
} /* namespace gr */
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