ca39682019-10-29Henrik Grubbström (Grubba) # Generate zic format 'leapseconds' from NIST format 'leap-seconds.list'.
9cef642014-10-16Henrik Grubbström (Grubba)  # This file is in the public domain.
ca39682019-10-29Henrik Grubbström (Grubba) # This program uses awk arithmetic. POSIX requires awk to support # exact integer arithmetic only through 10**10, which means for NTP # timestamps this program works only to the year 2216, which is the # year 1900 plus 10**10 seconds. However, in practice # POSIX-conforming awk implementations invariably use IEEE-754 double # and so support exact integers through 2**53. By the year 2216, # POSIX will almost surely require at least 2**53 for awk, so for NTP # timestamps this program should be good until the year 285,428,681 # (the year 1900 plus 2**53 seconds). By then leap seconds will be # long obsolete, as the Earth will likely slow down so much that # there will be more than 25 hours per day and so some other scheme # will be needed.
9cef642014-10-16Henrik Grubbström (Grubba) 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"
ca39682019-10-29Henrik Grubbström (Grubba)  print "# NIST format leap-seconds.list file, which can be copied from"
aa9f722018-12-18Henrik Grubbström (Grubba)  print "# <ftp://ftp.nist.gov/pub/time/leap-seconds.list>"
ca39682019-10-29Henrik Grubbström (Grubba)  print "# or <ftp://ftp.boulder.nist.gov/pub/time/leap-seconds.list>."
9cef642014-10-16Henrik Grubbström (Grubba)  print "# For more about leap-seconds.list, please see" print "# The NTP Timescale and Leap Seconds"
aa9f722018-12-18Henrik Grubbström (Grubba)  print "# <https://www.eecis.udel.edu/~mills/leap.html>."
9cef642014-10-16Henrik Grubbström (Grubba)  print ""
ca39682019-10-29Henrik Grubbström (Grubba)  print "# The rules for leap seconds are specified in Annex 1 (Time scales) of:" print "# Standard-frequency and time-signal emissions." print "# International Telecommunication Union - Radiocommunication Sector" print "# (ITU-R) Recommendation TF.460-6 (02/2002)" print "# <https://www.itu.int/rec/R-REC-TF.460-6-200202-I/>." print "# The International Earth Rotation and Reference Systems Service (IERS)"
cf65c72014-11-13Henrik Grubbström (Grubba)  print "# periodically uses leap seconds to keep UTC to within 0.9 s of UT1"
ca39682019-10-29Henrik Grubbström (Grubba)  print "# (a proxy for Earth's angle in space as measured by astronomers)"
aa9f722018-12-18Henrik Grubbström (Grubba)  print "# and publishes leap second data in a copyrighted file" print "# <https://hpiers.obspm.fr/iers/bul/bulc/Leap_Second.dat>." print "# See: Levine J. Coordinated Universal Time and the leap second."
af92cb2017-11-17Henrik Grubbström (Grubba)  print "# URSI Radio Sci Bull. 2016;89(4):30-6. doi:10.23919/URSIRSB.2016.7909995"
aa9f722018-12-18Henrik Grubbström (Grubba)  print "# <https://ieeexplore.ieee.org/document/7909995>."
36e21c2019-01-08Henrik Grubbström (Grubba)  print ""
ca39682019-10-29Henrik Grubbström (Grubba)  print "# There were no leap seconds before 1972, as no official mechanism" print "# accounted for the discrepancy between atomic time (TAI) and the earth's" print "# rotation. The first (\"1 Jan 1972\") data line in leap-seconds.list"
36e21c2019-01-08Henrik Grubbström (Grubba)  print "# does not denote a leap second; it denotes the start of the current definition"
ca39682019-10-29Henrik Grubbström (Grubba)  print "# of UTC."
9cef642014-10-16Henrik Grubbström (Grubba)  print ""
ca39682019-10-29Henrik Grubbström (Grubba)  print "# All leap-seconds are Stationary (S) at the given UTC time." print "# The correction (+ or -) is made at the given time, so in the unlikely" print "# event of a negative leap second, a line would look like this:" print "# Leap YEAR MON DAY 23:59:59 - S" print "# Typical lines look like this:" print "# Leap YEAR MON DAY 23:59:60 + S"
9cef642014-10-16Henrik Grubbström (Grubba) 
aa9f722018-12-18Henrik Grubbström (Grubba)  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"
ca39682019-10-29Henrik Grubbström (Grubba)  # Strip trailing CR, in case the input has CRLF form a la NIST. RS = "\r?\n" sstamp_init()
aa9f722018-12-18Henrik Grubbström (Grubba) }
26c3972015-02-14Henrik Grubbström (Grubba) 
ca39682019-10-29Henrik Grubbström (Grubba) /^#[ \t]*[Uu]pdated through/ || /^#[ \t]*[Ff]ile expires on/ {
26c3972015-02-14Henrik Grubbström (Grubba)  last_lines = last_lines $0 "\n" }
aa9f722018-12-18Henrik Grubbström (Grubba) /^#[$][ \t]/ { updated = $2 } /^#[@][ \t]/ { expires = $2 }
ca39682019-10-29Henrik Grubbström (Grubba) /^[ \t]*#/ { next }
9cef642014-10-16Henrik Grubbström (Grubba)  { NTP_timestamp = $1 TAI_minus_UTC = $2 if (old_TAI_minus_UTC) { if (old_TAI_minus_UTC < TAI_minus_UTC) { sign = "23:59:60\t+" } else { sign = "23:59:59\t-" }
ca39682019-10-29Henrik Grubbström (Grubba)  sstamp_to_ymdhMs(NTP_timestamp - 1, ss_NTP) printf "Leap\t%d\t%s\t%d\t%s\tS\n", \ ss_year, monthabbr[ss_month], ss_mday, sign
9cef642014-10-16Henrik Grubbström (Grubba)  } old_TAI_minus_UTC = TAI_minus_UTC }
26c3972015-02-14Henrik Grubbström (Grubba)  END {
aa9f722018-12-18Henrik Grubbström (Grubba)  # 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:"
ca39682019-10-29Henrik Grubbström (Grubba)  sstamp_to_ymdhMs(updated, ss_NTP) printf "#updated %d (%.4d-%.2d-%.2d %.2d:%.2d:%.2d UTC)\n", \ updated - epoch_minus_NTP, \ ss_year, ss_month, ss_mday, ss_hour, ss_min, ss_sec sstamp_to_ymdhMs(expires, ss_NTP) printf "#expires %d (%.4d-%.2d-%.2d %.2d:%.2d:%.2d UTC)\n", \ expires - epoch_minus_NTP, \ ss_year, ss_month, ss_mday, ss_hour, ss_min, ss_sec
26c3972015-02-14Henrik Grubbström (Grubba)  printf "\n%s", last_lines }
ca39682019-10-29Henrik Grubbström (Grubba)  # sstamp_to_ymdhMs - convert seconds timestamp to date and time # # Call as: # # sstamp_to_ymdhMs(sstamp, epoch_days) # # where: # # sstamp - is the seconds timestamp. # epoch_days - is the timestamp epoch in Gregorian days since 1600-03-01. # ss_NTP is appropriate for an NTP sstamp. # # Both arguments should be nonnegative integers. # On return, the following variables are set based on sstamp: # # ss_year - Gregorian calendar year # ss_month - month of the year (1-January to 12-December) # ss_mday - day of the month (1-31) # ss_hour - hour (0-23) # ss_min - minute (0-59) # ss_sec - second (0-59) # ss_wday - day of week (0-Sunday to 6-Saturday) # # The function sstamp_init should be called prior to using sstamp_to_ymdhMs. function sstamp_init() { # Days in month N, where March is month 0 and January month 10. ss_mon_days[ 0] = 31 ss_mon_days[ 1] = 30 ss_mon_days[ 2] = 31 ss_mon_days[ 3] = 30 ss_mon_days[ 4] = 31 ss_mon_days[ 5] = 31 ss_mon_days[ 6] = 30 ss_mon_days[ 7] = 31 ss_mon_days[ 8] = 30 ss_mon_days[ 9] = 31 ss_mon_days[10] = 31 # Counts of days in a Gregorian year, quad-year, century, and quad-century. ss_year_days = 365 ss_quadyear_days = ss_year_days * 4 + 1 ss_century_days = ss_quadyear_days * 25 - 1 ss_quadcentury_days = ss_century_days * 4 + 1 # Standard day epochs, suitable for epoch_days. # ss_MJD = 94493 # ss_POSIX = 135080 ss_NTP = 109513 } function sstamp_to_ymdhMs(sstamp, epoch_days, \ quadcentury, century, quadyear, year, month, day) { ss_hour = int(sstamp / 3600) % 24 ss_min = int(sstamp / 60) % 60 ss_sec = sstamp % 60 # Start with a count of days since 1600-03-01 Gregorian. day = epoch_days + int(sstamp / (24 * 60 * 60)) # Compute a year-month-day date with days of the month numbered # 0-30, months (March-February) numbered 0-11, and years that start # start March 1 and end after the last day of February. A quad-year # starts on March 1 of a year evenly divisible by 4 and ends after # the last day of February 4 years later. A century starts on and # ends before March 1 in years evenly divisible by 100. # A quad-century starts on and ends before March 1 in years divisible # by 400. While the number of days in a quad-century is a constant, # the number of days in each other time period can vary by 1. # Any variation is in the last day of the time period (there might # or might not be a February 29) where it is easy to deal with. quadcentury = int(day / ss_quadcentury_days) day -= quadcentury * ss_quadcentury_days ss_wday = (day + 3) % 7 century = int(day / ss_century_days) century -= century == 4 day -= century * ss_century_days quadyear = int(day / ss_quadyear_days) day -= quadyear * ss_quadyear_days year = int(day / ss_year_days) year -= year == 4 day -= year * ss_year_days for (month = 0; month < 11; month++) { if (day < ss_mon_days[month]) break day -= ss_mon_days[month] } # Convert the date to a conventional day of month (1-31), # month (1-12, January-December) and Gregorian year. ss_mday = day + 1 if (month <= 9) { ss_month = month + 3 } else { ss_month = month - 9 year++ } ss_year = 1600 + quadcentury * 400 + century * 100 + quadyear * 4 + year }