diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/ClockTAI.cpp | 107 |
1 files changed, 96 insertions, 11 deletions
diff --git a/src/ClockTAI.cpp b/src/ClockTAI.cpp index afd8025..5f9b750 100644 --- a/src/ClockTAI.cpp +++ b/src/ClockTAI.cpp @@ -25,6 +25,13 @@ along with ODR-DabMux. If not, see <http://www.gnu.org/licenses/>. */ +/* This file downloads the TAI-UTC bulletin from the USNO servers, parses + * it so that correct time can be communicated in EDI timestamps. + * + * This file contains self-test code that can be executed by running + * g++ -g -Wall -DTEST -DHAVE_CURL -std=c++11 -lcurl -lboost_regex ClockTAI.cpp Log.cpp -o taitest && ./taitest + */ + #ifdef HAVE_CONFIG_H # include "config.h" #endif @@ -32,6 +39,7 @@ #include "ClockTAI.h" #include "Log.h" +#include <time.h> #include <stdio.h> #include <errno.h> #if SUPPORT_SETTING_CLOCK_TAI @@ -45,8 +53,9 @@ #include <algorithm> #include <boost/regex.hpp> -/* Last line from bulletin, example: +/* Last two lines from bulletin, example: 2015 JUL 1 =JD 2457204.5 TAI-UTC= 36.0 S + (MJD - 41317.) X 0.0 S + 2017 JAN 1 =JD 2457754.5 TAI-UTC= 37.0 S + (MJD - 41317.) X 0.0 */ ClockTAI::ClockTAI() @@ -102,24 +111,82 @@ int ClockTAI::update_local_tai_clock(int offset) int ClockTAI::parse_tai_offset() { - boost::regex regex_offset("TAI-UTC= *([0-9.]+)"); + boost::regex regex_bulletin("([0-9]{4}) ([A-Z]{3}) +([0-9]+) =JD +[0-9.]+ +TAI-UTC= *([0-9.]+)"); + /* regex groups: Year Month Day Julian date Offset */ + + const std::array<std::string,12> months{"JAN", "FEB", "MAR", "APR", "MAY", "JUN", "JUL", "AUG", "SEP", "OCT", "NOV", "DEC"}; + + /* I'm not certain about the format they would use if the day is a two-digit number. Will they keep + * two spaces after the month? The regex should be resilient enough in that case. + */ + + time_t now = time(nullptr); + struct tm *utc_time_now = gmtime(&now); + + const int year = utc_time_now->tm_year + 1900; + const int month = utc_time_now->tm_mon; // January is 0 + if (month < 0 or month > 11) { + throw std::runtime_error("Invalid value for month"); + } + const int day = utc_time_now->tm_mday; + int tai_utc_offset = 0; int linecount = 0; + /* We cannot just take the last line, because it might + * be in the future, announcing an upcoming leap second. + * + * So we need to look at the current date, and compare it + * with the date of the leap second. + */ for (std::string line; std::getline(m_bulletin, line); ) { linecount++; - auto words_begin = - boost::sregex_token_iterator( - line.begin(), line.end(), regex_offset, 1); - auto words_end = boost::sregex_token_iterator(); - - for (auto w = words_begin; w != words_end; ++w) { - std::string s(*w); - tai_utc_offset = std::atoi(s.c_str()); - } + boost::smatch bulletin_entry; + + bool is_match = boost::regex_search(line, bulletin_entry, regex_bulletin); + if (is_match) { + + if (bulletin_entry.size() != 5) { + throw std::runtime_error("Incorrect number of matched TAI bulletin entries"); + } + const std::string bulletin_year(bulletin_entry[1]); + const std::string bulletin_month_name(bulletin_entry[2]); + const std::string bulletin_day(bulletin_entry[3]); + const std::string bulletin_offset(bulletin_entry[4]); + + const auto match = std::find(months.begin(), months.end(), bulletin_month_name); + if (match == months.end()) { + std::stringstream s; + s << "Month " << bulletin_month_name << " not in array!"; + std::runtime_error(s.str()); + } + + if ( (std::atoi(bulletin_year.c_str()) < year) or + + (std::atoi(bulletin_year.c_str()) == year and + std::distance(months.begin(), match) < month) or + + (std::atoi(bulletin_year.c_str()) == year and + std::distance(months.begin(), match) == month and + std::atoi(bulletin_day.c_str()) < day) ) { + tai_utc_offset = std::atoi(bulletin_offset.c_str()); + } +#if TEST + else { + std::cerr << "Ignoring offset " << bulletin_offset << " at date " + << bulletin_year << " " << bulletin_month_name << " " << + bulletin_day << " in the future" << std::endl; + } +#endif + } +#if TEST + else { + std::cerr << "No match for line " << line << std::endl; + } +#endif } if (linecount == 0) { @@ -222,3 +289,21 @@ void debug_tai_clk() } #endif +#if TEST +int main(int argc, char **argv) +{ + using namespace std; + + ClockTAI tai; + + try { + cerr << "Offset is " << tai.get_offset() << endl; + } + catch (std::exception &e) { + cerr << "Exception " << e.what() << endl; + } + + return 0; +} +#endif + |