# Generate the 'leapseconds' file from 'leap-seconds.list'. # This file is in the public domain. BEGIN { print "# Allowance for leap seconds added to each time zone file." print "" print "# This file is in the public domain." print "" print "# This file is generated automatically from the data in the public-domain" print "# leap-seconds.list file, which can be copied from" print "# " print "# or " print "# or ." print "# For more about leap-seconds.list, please see" print "# The NTP Timescale and Leap Seconds" print "# ." print "" print "# The International Earth Rotation and Reference Systems Service" print "# periodically uses leap seconds to keep UTC to within 0.9 s of UT1" print "# (which measures the true angular orientation of the earth in space)" print "# and publishes leap second data in a copyrighted file" print "# ." print "# See: Levine J. Coordinated Universal Time and the leap second." print "# URSI Radio Sci Bull. 2016;89(4):30-6. doi:10.23919/URSIRSB.2016.7909995" print "# ." print "# There were no leap seconds before 1972, because the official mechanism" print "# accounting for the discrepancy between atomic time and the earth's rotation" print "# did not exist." print "" print "# The correction (+ or -) is made at the given time, so lines" print "# will typically look like:" print "# Leap YEAR MON DAY 23:59:60 + R/S" print "# or" print "# Leap YEAR MON DAY 23:59:59 - R/S" print "" print "# If the leap second is Rolling (R) the given time is local time (unused here)." monthabbr[ 1] = "Jan" monthabbr[ 2] = "Feb" monthabbr[ 3] = "Mar" monthabbr[ 4] = "Apr" monthabbr[ 5] = "May" monthabbr[ 6] = "Jun" monthabbr[ 7] = "Jul" monthabbr[ 8] = "Aug" monthabbr[ 9] = "Sep" monthabbr[10] = "Oct" monthabbr[11] = "Nov" monthabbr[12] = "Dec" for (i in monthabbr) { monthnum[monthabbr[i]] = i monthlen[i] = 31 } monthlen[2] = 28 monthlen[4] = monthlen[6] = monthlen[9] = monthlen[11] = 30 } /^#\tUpdated through/ || /^#\tFile expires on:/ { last_lines = last_lines $0 "\n" } /^#[$][ \t]/ { updated = $2 } /^#[@][ \t]/ { expires = $2 } /^#/ { next } { NTP_timestamp = $1 TAI_minus_UTC = $2 hash_mark = $3 one = $4 month = $5 year = $6 if (old_TAI_minus_UTC) { if (old_TAI_minus_UTC < TAI_minus_UTC) { sign = "23:59:60\t+" } else { sign = "23:59:59\t-" } m = monthnum[month] - 1 if (m == 0) { year--; m = 12 } month = monthabbr[m] day = monthlen[m] day += m == 2 && year % 4 == 0 && (year % 100 != 0 || year % 400 == 0) printf "Leap\t%s\t%s\t%s\t%s\tS\n", year, month, day, sign } old_TAI_minus_UTC = TAI_minus_UTC } END { # The difference between the NTP and POSIX epochs is 70 years # (including 17 leap days), each 24 hours of 60 minutes of 60 # seconds each. epoch_minus_NTP = ((1970 - 1900) * 365 + 17) * 24 * 60 * 60 print "" print "# POSIX timestamps for the data in this file:" printf "#updated %s\n", updated - epoch_minus_NTP printf "#expires %s\n", expires - epoch_minus_NTP printf "\n%s", last_lines }