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-rw-r--r--src/ClockTAI.cpp107
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
+