1# Generate the 'leapseconds' file from 'leap-seconds.list'. 2 3# This file is in the public domain. 4 5BEGIN { 6 print "# Allowance for leap seconds added to each time zone file." 7 print "" 8 print "# This file is in the public domain." 9 print "" 10 print "# This file is generated automatically from the data in the public-domain" 11 print "# leap-seconds.list file, which can be copied from" 12 print "# <ftp://ftp.nist.gov/pub/time/leap-seconds.list>" 13 print "# or <ftp://ftp.boulder.nist.gov/pub/time/leap-seconds.list>" 14 print "# or <ftp://tycho.usno.navy.mil/pub/ntp/leap-seconds.list>." 15 print "# For more about leap-seconds.list, please see" 16 print "# The NTP Timescale and Leap Seconds" 17 print "# <https://www.eecis.udel.edu/~mills/leap.html>." 18 print "" 19 print "# The International Earth Rotation and Reference Systems Service" 20 print "# periodically uses leap seconds to keep UTC to within 0.9 s of UT1" 21 print "# (which measures the true angular orientation of the earth in space)" 22 print "# and publishes leap second data in a copyrighted file" 23 print "# <https://hpiers.obspm.fr/iers/bul/bulc/Leap_Second.dat>." 24 print "# See: Levine J. Coordinated Universal Time and the leap second." 25 print "# URSI Radio Sci Bull. 2016;89(4):30-6. doi:10.23919/URSIRSB.2016.7909995" 26 print "# <https://ieeexplore.ieee.org/document/7909995>." 27 print "" 28 print "# There were no leap seconds before 1972, because the official mechanism" 29 print "# accounting for the discrepancy between atomic time and the earth's rotation" 30 print "# did not exist. The first (\"1 Jan 1972\") data line in leap-seconds.list" 31 print "# does not denote a leap second; it denotes the start of the current definition" 32 print"# of UTC." 33 print "" 34 print "# The correction (+ or -) is made at the given time, so lines" 35 print "# will typically look like:" 36 print "# Leap YEAR MON DAY 23:59:60 + R/S" 37 print "# or" 38 print "# Leap YEAR MON DAY 23:59:59 - R/S" 39 print "" 40 print "# If the leap second is Rolling (R) the given time is local time (unused here)." 41 42 monthabbr[ 1] = "Jan" 43 monthabbr[ 2] = "Feb" 44 monthabbr[ 3] = "Mar" 45 monthabbr[ 4] = "Apr" 46 monthabbr[ 5] = "May" 47 monthabbr[ 6] = "Jun" 48 monthabbr[ 7] = "Jul" 49 monthabbr[ 8] = "Aug" 50 monthabbr[ 9] = "Sep" 51 monthabbr[10] = "Oct" 52 monthabbr[11] = "Nov" 53 monthabbr[12] = "Dec" 54 for (i in monthabbr) { 55 monthnum[monthabbr[i]] = i 56 monthlen[i] = 31 57 } 58 monthlen[2] = 28 59 monthlen[4] = monthlen[6] = monthlen[9] = monthlen[11] = 30 60} 61 62/^#\tUpdated through/ || /^#\tFile expires on:/ { 63 last_lines = last_lines $0 "\n" 64} 65 66/^#[$][ \t]/ { updated = $2 } 67/^#[@][ \t]/ { expires = $2 } 68 69/^#/ { next } 70 71{ 72 NTP_timestamp = $1 73 TAI_minus_UTC = $2 74 hash_mark = $3 75 one = $4 76 month = $5 77 year = $6 78 if (old_TAI_minus_UTC) { 79 if (old_TAI_minus_UTC < TAI_minus_UTC) { 80 sign = "23:59:60\t+" 81 } else { 82 sign = "23:59:59\t-" 83 } 84 m = monthnum[month] - 1 85 if (m == 0) { 86 year--; 87 m = 12 88 } 89 month = monthabbr[m] 90 day = monthlen[m] 91 day += m == 2 && year % 4 == 0 && (year % 100 != 0 || year % 400 == 0) 92 printf "Leap\t%s\t%s\t%s\t%s\tS\n", year, month, day, sign 93 } 94 old_TAI_minus_UTC = TAI_minus_UTC 95} 96 97END { 98 # The difference between the NTP and POSIX epochs is 70 years 99 # (including 17 leap days), each 24 hours of 60 minutes of 60 100 # seconds each. 101 epoch_minus_NTP = ((1970 - 1900) * 365 + 17) * 24 * 60 * 60 102 103 print "" 104 print "# POSIX timestamps for the data in this file:" 105 printf "#updated %s\n", updated - epoch_minus_NTP 106 printf "#expires %s\n", expires - epoch_minus_NTP 107 printf "\n%s", last_lines 108} 109