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# 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 is copied from:" 
  print "# ftp://ftp.nist.gov/pub/time/leap-seconds.list" 
  print "# For more about leap-seconds.list, please see" 
  print "# The NTP Timescale and Leap Seconds" 
  print "# https://www.eecis.udel.edu/~mills/leap.html" 
  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); see" 
  print "# 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 "# http://ieeexplore.ieee.org/document/7909995/" 
  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 until the early 1970s." 
  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 leapsecond is Rolling (R) the given time is local time." 
  print "# If the leapsecond is Stationary (S) the given time is UTC." 
  print "" 
  print "# Leap YEAR    MONTH   DAY     HH:MM:SS        CORR    R/S" 
} 
 
/^ *$/ { next } 
 
/^#\tUpdated through/ || /^#\tFile expires on:/ { 
    last_lines = last_lines $0 "\n" 
} 
 
/^#/ { 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-" 
        } 
        if (month == "Jan") { 
            year--; 
            month = "Dec"; 
            day = 31 
        } else if (month == "Jul") { 
            month = "Jun"; 
            day = 30 
        } 
        printf "Leap\t%s\t%s\t%s\t%s\tS\n", year, month, day, sign 
    } 
    old_TAI_minus_UTC = TAI_minus_UTC 
} 
 
END { 
    printf "\n%s", last_lines 
}