leapseconds.awk revision 339630
1308265Sgjb# Generate the 'leapseconds' file from 'leap-seconds.list'. 2308265Sgjb 3308265Sgjb# This file is in the public domain. 4308265Sgjb 5308265SgjbBEGIN { 6308265Sgjb print "# Allowance for leap seconds added to each time zone file." 7308265Sgjb print "" 8308265Sgjb print "# This file is in the public domain." 9308265Sgjb print "" 10308265Sgjb print "# This file is generated automatically from the data in the public-domain" 11339630Sphilip print "# leap-seconds.list file, which can be copied from" 12339630Sphilip print "# <ftp://ftp.nist.gov/pub/time/leap-seconds.list>" 13339630Sphilip print "# or <ftp://ftp.boulder.nist.gov/pub/time/leap-seconds.list>" 14339630Sphilip print "# or <ftp://tycho.usno.navy.mil/pub/ntp/leap-seconds.list>." 15308265Sgjb print "# For more about leap-seconds.list, please see" 16308265Sgjb print "# The NTP Timescale and Leap Seconds" 17339630Sphilip print "# <https://www.eecis.udel.edu/~mills/leap.html>." 18308265Sgjb print "" 19308265Sgjb print "# The International Earth Rotation and Reference Systems Service" 20308265Sgjb print "# periodically uses leap seconds to keep UTC to within 0.9 s of UT1" 21339630Sphilip print "# (which measures the true angular orientation of the earth in space)" 22339630Sphilip print "# and publishes leap second data in a copyrighted file" 23339630Sphilip print "# <https://hpiers.obspm.fr/iers/bul/bulc/Leap_Second.dat>." 24339630Sphilip print "# See: Levine J. Coordinated Universal Time and the leap second." 25325159Sphilip print "# URSI Radio Sci Bull. 2016;89(4):30-6. doi:10.23919/URSIRSB.2016.7909995" 26339630Sphilip print "# <https://ieeexplore.ieee.org/document/7909995>." 27308265Sgjb print "# There were no leap seconds before 1972, because the official mechanism" 28308265Sgjb print "# accounting for the discrepancy between atomic time and the earth's rotation" 29339630Sphilip print "# did not exist." 30308265Sgjb print "" 31308265Sgjb print "# The correction (+ or -) is made at the given time, so lines" 32308265Sgjb print "# will typically look like:" 33308265Sgjb print "# Leap YEAR MON DAY 23:59:60 + R/S" 34308265Sgjb print "# or" 35308265Sgjb print "# Leap YEAR MON DAY 23:59:59 - R/S" 36308265Sgjb print "" 37339630Sphilip print "# If the leap second is Rolling (R) the given time is local time (unused here)." 38339630Sphilip 39339630Sphilip monthabbr[ 1] = "Jan" 40339630Sphilip monthabbr[ 2] = "Feb" 41339630Sphilip monthabbr[ 3] = "Mar" 42339630Sphilip monthabbr[ 4] = "Apr" 43339630Sphilip monthabbr[ 5] = "May" 44339630Sphilip monthabbr[ 6] = "Jun" 45339630Sphilip monthabbr[ 7] = "Jul" 46339630Sphilip monthabbr[ 8] = "Aug" 47339630Sphilip monthabbr[ 9] = "Sep" 48339630Sphilip monthabbr[10] = "Oct" 49339630Sphilip monthabbr[11] = "Nov" 50339630Sphilip monthabbr[12] = "Dec" 51339630Sphilip for (i in monthabbr) { 52339630Sphilip monthnum[monthabbr[i]] = i 53339630Sphilip monthlen[i] = 31 54339630Sphilip } 55339630Sphilip monthlen[2] = 28 56339630Sphilip monthlen[4] = monthlen[6] = monthlen[9] = monthlen[11] = 30 57308265Sgjb} 58308265Sgjb 59308265Sgjb/^#\tUpdated through/ || /^#\tFile expires on:/ { 60308265Sgjb last_lines = last_lines $0 "\n" 61308265Sgjb} 62308265Sgjb 63339630Sphilip/^#[$][ \t]/ { updated = $2 } 64339630Sphilip/^#[@][ \t]/ { expires = $2 } 65339630Sphilip 66308265Sgjb/^#/ { next } 67308265Sgjb 68308265Sgjb{ 69308265Sgjb NTP_timestamp = $1 70308265Sgjb TAI_minus_UTC = $2 71308265Sgjb hash_mark = $3 72308265Sgjb one = $4 73308265Sgjb month = $5 74308265Sgjb year = $6 75308265Sgjb if (old_TAI_minus_UTC) { 76308265Sgjb if (old_TAI_minus_UTC < TAI_minus_UTC) { 77308265Sgjb sign = "23:59:60\t+" 78308265Sgjb } else { 79308265Sgjb sign = "23:59:59\t-" 80308265Sgjb } 81339630Sphilip m = monthnum[month] - 1 82339630Sphilip if (m == 0) { 83308265Sgjb year--; 84339630Sphilip m = 12 85308265Sgjb } 86339630Sphilip month = monthabbr[m] 87339630Sphilip day = monthlen[m] 88339630Sphilip day += m == 2 && year % 4 == 0 && (year % 100 != 0 || year % 400 == 0) 89308265Sgjb printf "Leap\t%s\t%s\t%s\t%s\tS\n", year, month, day, sign 90308265Sgjb } 91308265Sgjb old_TAI_minus_UTC = TAI_minus_UTC 92308265Sgjb} 93308265Sgjb 94308265SgjbEND { 95339630Sphilip # The difference between the NTP and POSIX epochs is 70 years 96339630Sphilip # (including 17 leap days), each 24 hours of 60 minutes of 60 97339630Sphilip # seconds each. 98339630Sphilip epoch_minus_NTP = ((1970 - 1900) * 365 + 17) * 24 * 60 * 60 99339630Sphilip 100339630Sphilip print "" 101339630Sphilip print "# POSIX timestamps for the data in this file:" 102339630Sphilip printf "#updated %s\n", updated - epoch_minus_NTP 103339630Sphilip printf "#expires %s\n", expires - epoch_minus_NTP 104308265Sgjb printf "\n%s", last_lines 105308265Sgjb} 106