From f575359292df91feb7011e415186a370ff17e920 Mon Sep 17 00:00:00 2001
From: Bruce Flynn <brucef@ssec.wisc.edu>
Date: Fri, 22 Dec 2017 10:40:15 -0600
Subject: [PATCH] changes to timecode helpers
---
edosl0util/headers.py | 43 ++++++++++++++++++++----------------------
edosl0util/timecode.py | 26 ++++++++++++-------------
setup.py | 1 +
3 files changed, 34 insertions(+), 36 deletions(-)
diff --git a/edosl0util/headers.py b/edosl0util/headers.py
index e145e58..4a467b0 100644
--- a/edosl0util/headers.py
+++ b/edosl0util/headers.py
@@ -13,13 +13,10 @@ See:
"""
__copyright__ = "Copyright (C) 2015 University of Wisconsin SSEC. All rights reserved."
-
import ctypes as c
from datetime import datetime, timedelta
-
-from edosl0util.timecode import cds_stamp, cds_to_timestamp
-
+from edosl0util.timecode import cds_to_dt
GROUP_FIRST = 0b01
GROUP_LAST = 0b10
@@ -63,12 +60,10 @@ class Timecode(BaseStruct):
"""
Secondary header timecode baseclass.
"""
+
def __repr__(self):
return str(self.asdatetime())
- def astimestamp(self):
- raise NotImplementedError()
-
def asdatetime(self):
raise NotImplementedError()
@@ -98,20 +93,16 @@ class AquaCucTimecode(Timecode):
EPOCH_SECS = (EPOCH - datetime(1970, 1, 1)).total_seconds()
SUB_SECOND_UNITS = 15.2
- def astimestamp(self):
- tc = self.timecode
- return cds_to_timestamp(tc.days, tc.milliseconds, tc.microseconds, self.EPOCH_SECS)
-
def asdatetime(self):
"""
Return converted to UTC where leap seconds are as defined in `leap_seconds`.
-
- FIXME: Verify this conversion is correct, specfically the use of
- SUB_SECOND_UNIT.
"""
- seconds = self.seconds + self.leap_seconds
micros = self.SUB_SECOND_UNITS * self.sub_seconds
- return self.EPOCH + timedelta(seconds=seconds, microseconds=micros)
+ seconds = self.seconds + self.leap_seconds
+ return cds_to_dt(
+ (seconds - self.leap_seconds) // 86400,
+ micros // 1e3,
+ micros % 1e3)
class DaySegmentedTimecode(Timecode):
@@ -125,14 +116,8 @@ class DaySegmentedTimecode(Timecode):
('microseconds', c.c_uint16)
]
- EPOCH = datetime(1958, 1, 1)
- EPOCH_SECS = (EPOCH - datetime(1970, 1, 1)).total_seconds()
-
- def astimestamp(self):
- return cds_to_timestamp(self.days, self.milliseconds, self.microseconds, self.EPOCH_SECS)
-
def asdatetime(self):
- return cds_stamp(self.days, self.milliseconds, self.microseconds)
+ return cds_to_dt(self.days, self.milliseconds, self.microseconds)
class AquaGirdSecondaryHeader(BaseStruct):
@@ -178,12 +163,22 @@ class JpssFirstSecondaryHeader(BaseStruct):
]
+class ViirsPacketId(BaseStruct):
+ _pack_ = 1
+ _fields_ = [
+ ('scan_number', c.c_uint32),
+ ('packet_time', DaySegmentedTimecode),
+ ]
+
+
_jpss_headers = {
GROUP_FIRST: JpssFirstSecondaryHeader,
GROUP_CONTINUING: None,
GROUP_LAST: None,
GROUP_STANDALONE: JpssSecondaryHeader,
}
+
+
def jpss_header_lookup(primary_header):
return _jpss_headers.get(primary_header.sequence_grouping)
@@ -269,4 +264,6 @@ def aqua_header_lookup(primary_header):
apid = primary_header.apid
grouping = primary_header.sequence_grouping
return _aqua_headers.get((apid, grouping))
+
+
_aqua_headers = aqua_headers()
diff --git a/edosl0util/timecode.py b/edosl0util/timecode.py
index a505e6c..048e6ae 100644
--- a/edosl0util/timecode.py
+++ b/edosl0util/timecode.py
@@ -1,31 +1,31 @@
# encoding: utf-8
__copyright__ = "Copyright (C) 2015 University of Wisconsin SSEC. All rights reserved."
-from datetime import datetime, timedelta
+from astropy.time import Time, TimeDelta
-JPSS_EPOCH = datetime(1958, 1, 1)
-UNIX_EPOCH = datetime(1970, 1, 1)
+IET_EPOCH = Time('1958-01-01', scale='tai')
+UNIX_EPOCH = Time('1970-01-01', scale='utc')
def unixtime(dt):
"""
Datetime to Unix timestamp.
"""
- if dt > UNIX_EPOCH:
- return (dt - UNIX_EPOCH).total_seconds()
- return (UNIX_EPOCH - dt).total_seconds()
+ return (dt - UNIX_EPOCH).total_seconds()
-def cds_to_timestamp(days, millis, microseconds, epoch):
+def cds_to_dt(days, millis, microseconds):
"""
- CDS to unix timestamp seconds.
+ CCSDS Day Segmented timecode to UTC datetime.
"""
- return epoch + (86400 * days) + (millis / 1000.) + (microseconds / 1000000.)
+ iet = cds_to_iet(days, millis, microseconds)
+ return (IET_EPOCH + TimeDelta(iet, format='sec')).utc.datetime
-def cds_stamp(days, millis, microseconds, epoch=JPSS_EPOCH):
+def cds_to_iet(days, ms, us):
"""
- CCSDS Day Segmented timecode to UTC datetime.
+ CCSDS Day Segmented timecode parts to IET
"""
- return epoch + timedelta(days=days,
- seconds=millis / 1000.0 + (microseconds / 1000000.))
+ ccsds_epoch = Time('1958-01-01', scale='tai')
+ day = Time(ccsds_epoch.jd + days, scale='utc', format='jd') - IET_EPOCH
+ return int(day.sec * 1e6 + ms * 1e3 + us)
diff --git a/setup.py b/setup.py
index 1711520..d63918f 100644
--- a/setup.py
+++ b/setup.py
@@ -14,6 +14,7 @@ setup(
],
install_requires=[
'h5py',
+ 'astropy',
],
extras_require={
'testing': [
--
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