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<?php |
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/** |
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* Time.php |
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* DQSEGDB - Convert segdb-format data to DQSEGDB. |
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* |
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* @link https://github.com/ligovirgo/dqsegdb/blob/master/server/db/db_utils/segdb_to_dqsegdb_auto_converter/src/classes/TimeConversion.php Source |
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* @link https://www.andrews.edu/~tzs/timeconv/timealgorithm.html Algorithm |
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*/ |
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namespace Bmatovu\Conversion; |
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/** |
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* Class Time. |
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*/ |
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class Time |
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{ |
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/** |
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* Define GPS leap seconds. |
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* |
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* @return array |
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*/ |
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private static function getleaps() |
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{ |
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$leaps = [ |
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46828800, |
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78364801, |
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109900802, |
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173059203, |
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252028804, |
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315187205, |
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346723206, |
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393984007, |
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425520008, |
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457056009, |
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504489610, |
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551750411, |
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599184012, |
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820108813, |
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914803214, |
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1025136015, |
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]; |
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return $leaps; |
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} |
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/** |
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* If a GPS second is a leap second. |
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* |
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* @param int $gpsTime GPS Time |
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* |
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* @return bool |
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*/ |
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private static function isleap($gpsTime) |
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{ |
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$isLeap = false; |
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$leaps = self::getleaps(); |
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$lenLeaps = count($leaps); |
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for ($i = 0; $i < $lenLeaps; $i++) { |
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if ($gpsTime == $leaps[$i]) { |
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$isLeap = true; |
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} |
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} |
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return $isLeap; |
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} |
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/** |
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* Count number of leap seconds that have passed. |
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* |
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* @param int $gpsTime GPS Time |
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* @param string $dirFlag ?? |
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* |
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* @return int |
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*/ |
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private static function countleaps($gpsTime, $dirFlag) |
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{ |
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$leaps = self::getleaps(); |
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$lenLeaps = count($leaps); |
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$nleaps = 0; // number of leap seconds prior to gpsTime |
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for ($i = 0; $i < $lenLeaps; $i++) { |
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if (!strcmp('unix2gps', $dirFlag)) { |
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if ($gpsTime >= $leaps[$i] - $i) { |
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$nleaps++; |
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} |
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} elseif (!strcmp('gps2unix', $dirFlag)) { |
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if ($gpsTime >= $leaps[$i]) { |
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$nleaps++; |
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} |
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} else { |
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echo 'ERROR Invalid Flag!'; |
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} |
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} |
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return $nleaps; |
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} |
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/** |
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* Convert GPS Time to Unix Time. |
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* |
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* @param int $gpsTime GPS Time |
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* |
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* @return mixed |
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*/ |
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public static function gps2unix($gpsTime) |
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{ |
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// Add offset in seconds |
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$unixTime = $gpsTime + 315964800; |
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$nleaps = self::countleaps($gpsTime, 'gps2unix'); |
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$unixTime = $unixTime - $nleaps; |
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if (self::isleap($gpsTime)) { |
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$unixTime = $unixTime + 0.5; |
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} |
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return $unixTime; |
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} |
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/** |
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* Convert Unix Time to GPS Time. |
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* |
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* @param int $unixTime Unix Time |
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* |
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* @return mixed |
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*/ |
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public static function unix2gps($unixTime) |
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{ |
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// Add offset in seconds |
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if (fmod($unixTime, 1) != 0) { |
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$unixTime = $unixTime - 0.5; |
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$isLeap = 1; |
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} else { |
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$isLeap = 0; |
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} |
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$gpsTime = $unixTime - 315964800; |
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$nleaps = self::countleaps($gpsTime, 'unix2gps'); |
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$gpsTime = $gpsTime + $nleaps + $isLeap; |
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return $gpsTime; |
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} |
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} |
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