77 lines
2.5 KiB
Awk
77 lines
2.5 KiB
Awk
# Generate the 'leapseconds' file from 'leap-seconds.list'.
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# This file is in the public domain.
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BEGIN {
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print "# Allowance for leap seconds added to each time zone file."
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print ""
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print "# This file is in the public domain."
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print ""
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print "# This file is generated automatically from the data in the public-domain"
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print "# leap-seconds.list file available from most NIST time servers."
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print "# If the URL <ftp://time.nist.gov/pub/leap-seconds.list> does not work,"
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print "# you should be able to pick up leap-seconds.list from a secondary NIST server."
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print "# See <http://tf.nist.gov/tf-cgi/servers.cgi> for a list of secondary servers."
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print "# For more about leap-seconds.list, please see"
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print "# The NTP Timescale and Leap Seconds"
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print "# http://www.eecis.udel.edu/~mills/leap.html"
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print ""
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print "# The International Earth Rotation and Reference Systems Service"
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print "# periodically uses leap seconds to keep UTC to within 0.9 s of UT1"
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print "# (which measures the true angular orientation of the earth in space); see"
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print "# Terry J Quinn, The BIPM and the accurate measure of time,"
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print "# Proc IEEE 79, 7 (July 1991), 894-905 <http://dx.doi.org/10.1109/5.84965>."
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print "# There were no leap seconds before 1972, because the official mechanism"
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print "# accounting for the discrepancy between atomic time and the earth's rotation"
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print "# did not exist until the early 1970s."
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print ""
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print "# The correction (+ or -) is made at the given time, so lines"
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print "# will typically look like:"
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print "# Leap YEAR MON DAY 23:59:60 + R/S"
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print "# or"
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print "# Leap YEAR MON DAY 23:59:59 - R/S"
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print ""
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print "# If the leapsecond is Rolling (R) the given time is local time."
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print "# If the leapsecond is Stationary (S) the given time is UTC."
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print ""
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print "# Leap YEAR MONTH DAY HH:MM:SS CORR R/S"
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}
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/^ *$/ { next }
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/^#\tUpdated through/ || /^#\tFile expires on:/ {
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last_lines = last_lines $0 "\n"
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}
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/^#/ { next }
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{
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NTP_timestamp = $1
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TAI_minus_UTC = $2
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hash_mark = $3
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one = $4
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month = $5
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year = $6
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if (old_TAI_minus_UTC) {
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if (old_TAI_minus_UTC < TAI_minus_UTC) {
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sign = "23:59:60\t+"
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} else {
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sign = "23:59:59\t-"
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}
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if (month == "Jan") {
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year--;
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month = "Dec";
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day = 31
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} else if (month == "Jul") {
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month = "Jun";
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day = 30
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}
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printf "Leap\t%s\t%s\t%s\t%s\tS\n", year, month, day, sign
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}
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old_TAI_minus_UTC = TAI_minus_UTC
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}
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END {
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printf "\n%s", last_lines
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}
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