freebsd-dev/contrib/tzdata/leapseconds.awk
Glen Barber ba2b2efdfa MFV r308265: Update tzdata to 2016i.
Sponsored by:	The FreeBSD Foundation
2016-11-03 23:34:11 +00:00

77 lines
2.5 KiB
Awk

# 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 available from most NIST time servers."
print "# If the URL <ftp://time.nist.gov/pub/leap-seconds.list> does not work,"
print "# you should be able to pick up leap-seconds.list from a secondary NIST server."
print "# See <http://tf.nist.gov/tf-cgi/servers.cgi> for a list of secondary servers."
print "# For more about leap-seconds.list, please see"
print "# The NTP Timescale and Leap Seconds"
print "# http://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 "# Terry J Quinn, The BIPM and the accurate measure of time,"
print "# Proc IEEE 79, 7 (July 1991), 894-905 <http://dx.doi.org/10.1109/5.84965>."
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
}