Subtract the right offset.

1 files changed, 8 insertions, 6 deletions

diff --git a/leapsecond.py b/leapsecond.py
index dac185c9..565ad5bb 100755
--- a/leapsecond.py
+++ b/leapsecond.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env python
 #
-# Get the current leap-second value.  This is the offset between GMT and
+# Get the current leap-second value.  This is the offset between UTC and
 # GPS time, which changes occasionally due to variations in the Earth's
 # rotation.
 #
@@ -11,27 +11,29 @@ __locations = [
     # U.S. Navy's offset-history file
     "ftp://maia.usno.navy.mil/ser7/tai-utc.dat",
     r" TAI-UTC= +([0-9-]+)[^\n]*\n$",
-    -1,
+    1,
+    19,	# Magic TAI-GPS offset
     ),
     (
     # International Earth Rotation Service Bulletin C
     "http://hpiers.obspm.fr/iers/bul/bulc/bulletinc.dat",
     r" UTC-TAI = ([0-9-]+)",
-    1,
+    -1,
+    19,	# Magic TAI-GPS offset
     ),
 ]
 
 def retrieve():
-    "Retrieve current leap-second from web sources."
+    "Retrieve current leap-second from Web sources."
     random.shuffle(__locations)	# To spread the load
-    for (url, regexp, sign) in __locations:
+    for (url, regexp, sign, offset) in __locations:
         try:
             ifp = urllib.urlopen(url)
             txt = ifp.read()
             ifp.close()
             m = re.search(regexp, txt)
             if m:
-                return int(m.group(1)) * sign
+                return int(m.group(1)) * sign - offset
         except:
             pass
     else: