started the spotting code. Got most of the utilities working.

[spider.git] / perl / julian.pm

diff --git a/perl/julian.pm b/perl/julian.pm
new file mode 100644 (file)
index 0000000..c5cf43c
--- /dev/null
+++ b/perl/julian.pm
@@ -0,0 +1,117 @@
+#
+# various julian date calculations
+#
+# Copyright (c) - 1998 Dirk Koopman G1TLH
+#
+# $Id$
+#
+
+package julian;
+
+use FileHandle;
+use DXDebug;
+
+use strict;
+
+my @days = (31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31);
+
+# take a unix date and transform it into a julian day (ie (1998, 13) = 13th day of 1998)
+sub unixtoj
+{
+  my ($pkg, $t) = @_;
+  my ($day, $mon, $year) = (gmtime($t))[3..5];
+  my $jday;
+  
+  # set the correct no of days for february
+  if ($year < 100) {
+    $year += ($year < 50) ? 2000 : 1900;
+  }
+  $days[1] = isleap($year) ? 29 : 28;
+  for (my $i = 0, $jday = 0; $i < $mon; $i++) {
+    $jday += $days[$i];
+  }
+  $jday += $day;
+  return ($year, $jday);
+}
+
+# take a julian date and subtract a number of days from it, returning the julian date
+sub sub
+{
+  my ($pkg, $year, $day, $amount) = @_;
+  my $diny = isleap($year) ? 366 : 365;
+  $day -= $amount;
+  while ($day <= 0) {
+    $day += $diny;
+       $year -= 1;
+       $diny = isleap($year) ? 366 : 365;
+  }
+  return ($year, $day);
+}
+
+sub add
+{
+  my ($pkg, $year, $day, $amount) = @_;
+  my $diny = isleap($year) ? 366 : 365;
+  $day += $amount;
+  while ($day > $diny) {
+    $day -= $diny;
+       $year += 1;
+       $diny = isleap($year) ? 366 : 365;
+  }
+  return ($year, $day);
+} 
+
+sub cmp
+{
+  my ($pkg, $y1, $d1, $y2, $d2) = @_;
+  return $d1 - $d2 if ($y1 == $y2);
+  return $y1 - $y2;
+}
+
+# is it a leap year?
+sub isleap
+{
+  my $year = shift;
+  return ($year % 4 == 0 && ($year % 100 != 0 || $year % 400 == 0)) ? 1 : 0; 
+}
+
+# open a data file with prefix $fn/$year/$day.dat and return an object to it
+sub open
+{
+  my ($name, $pkg, $fn, $year, $day, $mode) = @_;
+
+  # if we are writing, check that the directory exists
+  if (defined $mode) {
+    my $dir = "$fn/$year";
+       mkdir($dir, 0777) if ! -e $dir;
+  }
+  my $self = {};
+  $self->{fn} = sprintf "$fn/$year/%03d.dat", $day;
+  $mode = 'r' if !$mode;
+  my $fh = new FileHandle $self->{fn}, $mode;
+  return undef if !$fh;
+  $fh->autoflush(1) if $mode ne 'r';         # make it autoflushing if writable
+  $self->{fh} = $fh;
+  $self->{year} = $year;
+  $self->{day} = $day;
+  dbg("julian", "opening $self->{fn}\n");
+  
+  return bless $self, $pkg;
+}
+
+# close the data file
+sub close
+{
+  my $self = shift;
+  undef $self->{fh};      # close the filehandle
+  delete $self->{fh};
+}
+
+sub DESTROY               # catch undefs and do what is required further do the tree
+{
+  my $self = shift;
+  dbg("julian", "closing $self->{fn}\n");
+  undef $self->{fh} if defined $self->{fh};
+} 
+
+1;