don't use astroy when parsing packets

edosl0util/timecode.py

 # encoding: utf-8
+from datetime import timedelta, datetime
+
 __copyright__ = "Copyright (C) 2015 University of Wisconsin SSEC. All rights reserved."
 
 from astropy.time import Time, TimeDelta
 
-IET_EPOCH = Time('1958-01-01', scale='tai')
-UNIX_EPOCH = Time('1970-01-01', scale='utc')
-
 
 def unixtime(dt):
     """
     Datetime to Unix timestamp.
     """
-    return (dt - UNIX_EPOCH).total_seconds()
+    return (dt - datetime(1970, 1, 1)).total_seconds()
 
 
 def cds_to_dt(days, millis, microseconds):
     """
     CCSDS Day Segmented timecode to UTC datetime.
     """
-    iet = cds_to_iet(days, millis, microseconds)
-    return (IET_EPOCH + TimeDelta(iet, format='sec')).utc.datetime
+    return datetime(1970, 1, 1) + timedelta(days=days, microseconds=1e6 * millis + microseconds)
 
 
 def cds_to_iet(days, ms, us):
     """
-    CCSDS Day Segmented timecode parts to IET
+    CCSDS Day Segmented timecode parts to IET (microseconds)
     """
+    iet_epoch = Time('1958-01-01', scale='tai')
     ccsds_epoch = Time('1958-01-01', scale='tai')
-    day = Time(ccsds_epoch.jd + days, scale='utc', format='jd') - IET_EPOCH
+    day = Time(ccsds_epoch.jd + days, scale='utc', format='jd') - iet_epoch
     return int(day.sec * 1e6 + ms * 1e3 + us)

setup.py

@@ -13,8 +13,9 @@ setup(
         'setuptools_scm'
     ],
     install_requires=[
-        'h5py',
         'astropy',
+        'attrs',
+        'h5py',
     ],
     extras_require={
         'testing': [

tests/test_timecode.py

-from datetime import datetime, timedelta
-from edosl0util import timecode
-
-
-def test_unixtime():
-    assert timecode.unixtime(timecode.UNIX_EPOCH) == 0
-
-
-def test_cds_to_timestamp():
-    epoch = 0
-
-    secs = timecode.cds_to_timestamp(0, 0, 0, epoch)
-    assert secs == 0
-
-    secs = timecode.cds_to_timestamp(0, 0, 999, epoch)
-    assert secs == 0.000999
-
-    secs = timecode.cds_to_timestamp(1, 1, 999, epoch)
-    assert secs == 86400.001999
-
-
-def test_cds_stamp():
-    epoch = timecode.UNIX_EPOCH
-
-    assert timecode.cds_stamp(0, 0, 0, epoch) == timecode.UNIX_EPOCH
-
-    assert timecode.cds_stamp(0, 0, 999, epoch) == datetime(1970, 1, 1, 0, 0, 0, 999)
-
-    assert timecode.cds_stamp(1, 1, 999, epoch) == datetime(1970, 1, 2, 0, 0, 0, 1999)