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$NetBSD: patch-weekno.perl,v 1.1 2014/11/05 22:41:38 he Exp $
Fix this so that it uses week numbering according to ISO 8601.
--- weekno.perl.orig 1995-10-17 13:44:49.000000000 +0000
+++ weekno.perl
@@ -1,7 +1,7 @@
#!/local/bin/perl
# Package for date handling
-# Use the PERL std library timelocal - older had his own
-require "timelocal.pl";
+# Use the PERL std package Time::Local
+use Time::Local;
package DATE;
# J F M A M J J A S O N D
@@ -51,7 +51,21 @@ sub weekno {
sub firstdayfirstweek {
-# Return first day of week 1 of any year
+# Return the day of the year (0 is Jan 1st)
+# for the first day of week 1 of any year.
+#
+# Quoting strftime(3):
+# %V is replaced by the week number of the year (Monday as the first day
+# of the week) as a decimal number [01,53]. According to ISO 8601 the
+# week containing January 1 is week 1 if it has four or more days in
+# the new year, otherwise it is week 53 of the previous year, and the
+# next week is week 1. The year is given by the `%G' conversion
+# specification.
+#
+# So this will return a negative value in some cases, i.e. when
+# Jan 1st falls on either of Tuesday, Wednesday or Thursday, and
+# will be positive (1) or zero for Sunday or Monday respectively.
+#
local($y) = @_;
local($ret);
# Get time of January 1, 0.0.0.0
@@ -59,13 +73,14 @@ sub firstdayfirstweek {
local($firsttime) = &main'timelocal(0, 0, 0, 1, 0, $y, 0, 0, 0);
local(@firstday) = localtime($firsttime);
local($wday) = $firstday[6];
- # Rule works for some years.....89 to 92 tested, they all hit branch 2...
- if ($wday > 3) {
- $ret = 8 - $wday;
+ # Weekday 4 is Thursday (localtime returns zero-based with Sunday = 0)
+ if ($wday <= 4) {
+ $ret = 1 - $wday; # first day of week 1 may be in late December
+ # The exception is when Jan 1 = Sunday (wday 0)
} else {
- $ret = 1 - $wday;
+ $ret = 8 - $wday; # first day of week 1 is in January
}
- $ret;
+ return $ret;
}
sub firstinweek {
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