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author | Piotr Krysik <ptrkrysik@gmail.com> | 2017-10-31 11:30:59 +0100 |
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committer | Piotr Krysik <ptrkrysik@gmail.com> | 2017-10-31 11:30:59 +0100 |
commit | 34ce7a02f071c0aa4661799aa566236c92955d74 (patch) | |
tree | fcc6a4fcc0fbe2680a295b2a3ae25ac2547c2488 /lib | |
parent | 29ec39b3bd0c03113118f3735b2ea83f0d262844 (diff) |
Added C++ version of fn_time
Diffstat (limited to 'lib')
-rw-r--r-- | lib/misc_utils/CMakeLists.txt | 1 | ||||
-rw-r--r-- | lib/misc_utils/fn_time.cc | 105 |
2 files changed, 106 insertions, 0 deletions
diff --git a/lib/misc_utils/CMakeLists.txt b/lib/misc_utils/CMakeLists.txt index 1c51fb6..8597553 100644 --- a/lib/misc_utils/CMakeLists.txt +++ b/lib/misc_utils/CMakeLists.txt @@ -32,5 +32,6 @@ add_sources( message_printer_impl.cc msg_to_tag_impl.cc tmsi_dumper_impl.cc + fn_time.cc ) diff --git a/lib/misc_utils/fn_time.cc b/lib/misc_utils/fn_time.cc new file mode 100644 index 0000000..5248211 --- /dev/null +++ b/lib/misc_utils/fn_time.cc @@ -0,0 +1,105 @@ +/* -*- c++ -*- */ +/* @file + * @author Piotr Krysik <ptrkrysik@gmail.com> + * @author Vadim Yanitskiy <axilirator@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. + * + */ + +#include <grgsm/misc_utils/fn_time.h> +#include <math.h> +#include <uhd/types/time_spec.hpp> + +#define GSM_HYPER_FRAME 26 * 51 * 2048 +#define GSM_SYM_RATE 13.0e6 / 48.0 + +#define GSM_TS_PERIOD 156.25 / GSM_SYM_RATE +#define GSM_FN_PERIOD 8 * GSM_TS_PERIOD + +namespace gr { + namespace gsm { + using namespace uhd; + /** + * Computes difference between two frame numbers modulo + * GSM_HYPER_FRAME / 2. The result is correct if difference + * between the frame numbers is not bigger than GSM_HYPER_FRAME / 2. + * @param fn1 first frame number + * @param fn2 second frame number + * @return computed difference + */ + static uint32_t fnmod_delta(uint32_t fn1, uint32_t fn2) + { + uint32_t delta, h2; + + delta = (fn1 % GSM_HYPER_FRAME) - (fn2 % GSM_HYPER_FRAME); + h2 = GSM_HYPER_FRAME / 2; + + if (delta >= h2) + delta -= GSM_HYPER_FRAME; + else + delta += GSM_HYPER_FRAME; + + return delta; + } + + static int fn_time_diff_delta(uint32_t fn, uint32_t fn_ref, + time_spec_t time_diff_hint) + { + int frames_diff, fn_delta; + + frames_diff = int(round(time_diff_hint.get_real_secs() / GSM_FN_PERIOD)); + fn_delta = fnmod_delta(fn, fn_ref + frames_diff) + frames_diff; + + return fn_delta; + } + + /** + * Computes difference between reference frame number + * and a second frame number. + * @param fn_ref reference frame number modulo GSM_HYPER_FRAME + * @param fn second frame number modulo GSM_HYPER_FRAME + * @param time_ref precise timestamp of the first sample in the fn_ref + * @param time_hint coarse time for fn that is used as a hint to avoid + * ambiguities caused by modulo operation applied to + * frame numbers + * @return difference between fn_ref and fn + */ + time_spec_t fn_time_delta(uint32_t fn_ref, time_spec_t time_ref, uint32_t fn_x, + time_spec_t time_hint, uint32_t ts_num, uint32_t ts_ref) + { + time_spec_t time_diff_hint = time_hint - time_ref; + uint32_t fn_delta = fn_time_diff_delta(fn_x,fn_ref, time_diff_hint); + time_spec_t time_x_precise = fn_delta * GSM_FN_PERIOD + + time_ref + (ts_num - ts_ref) * GSM_TS_PERIOD; + + return time_x_precise; + } +/* + def fn_time_delta(fn_ref, time_ref, fn_x, time_hint=None, ts_num=0, ts_ref=0): + if time_hint is None: + time_hint = time_ref + + time_diff_hint = time_hint-time_ref + fn_delta = fn_time_diff_delta(fn_x,fn_ref, time_diff_hint) + time_x_precise = fn_delta*__frame_period+time_ref+(ts_num-ts_ref)*__ts_period + + return fn_delta, time_x_precise +*/ + } /* namespace gsm */ +} /* namespace gr */ + |