Beginnings of rdrgen module

edosl0util/rdrgen.py

+import ctypes
+from collections import OrderedDict
+
+import attr
+from astropy.time import Time, TimeDelta
+import numpy as np
+
+from edosl0util.jpssrdr import StaticHeader, Apid as ApidListItem, PacketTracker
+
+
+def prototype():
+    pds_file = 'P1571289CRISSCIENCEA6T17230135400001.PDS'
+    satellite = 'snpp'
+    rdr_type = 'CRIS-SCIENCE-RDR'
+    granule_iet = 1881755831079000
+
+
+class RdrBlobBuilder(object):
+    def __init__(self, rdr_type, sat, granule_iet):
+        self.sat = sat
+
+
+def build_rdr_blob(pkt_stream, rdr_type, sat, granule_iet):
+    granule_iet_end = granule_iet + rdr_type.granularity
+
+    total_pkt_size = 0
+    apid_info = OrderedDict()
+    total_trackers = 0
+    all_pkts = []
+    for apid in rdr_type.apids:
+        apid_info[apid.num] = {
+            'name': apid.name,
+            'pkts_reserved': apid.max_expected, 'pkts_received': 0,
+            'first_tracker_index': total_trackers,
+            'pkt_info': [{} for _ in range(apid.max_expected)]}
+        total_trackers += apid.max_expected
+
+    for pkt in pkt_stream:
+        if pkt.apid not in apid_info:
+            continue
+        pkt_iet = timecode_to_iet(pkt.secondary_header.timecode)
+        if not granule_iet <= pkt_iet < granule_iet_end:
+            continue
+        info = apid_info[pkt.apid]
+        pkt_info = info['pkt_info'][info['pkts_received']]
+        pkt_info['obs_time'] = pkt_iet
+        pkt_info['seq_num'] = pkt.seqid
+        pkt_info['size'] = pkt.size
+        pkt_info['offset'] = total_pkt_size
+        info['pkts_received'] += 1
+        total_pkt_size += pkt.size
+        all_pkts.append(pkt)
+
+    apid_list_offset = ctypes.sizeof(StaticHeader)
+    pkt_tracker_offset = apid_list_offset + len(apid_info) * ctypes.sizeof(ApidListItem)
+    ap_storage_offset = pkt_tracker_offset + total_trackers * ctypes.sizeof(PacketTracker)
+    buf_size = ap_storage_offset + total_pkt_size
+    buf = np.zeros([buf_size], np.uint8)  # zeros needed to null-pad strings
+
+    header = StaticHeader.from_buffer(buf)
+    header.satellite = sat  # XXX: mapping?
+    header.sensor = rdr_type.sensor
+    header.type_id = rdr_type.type_id
+    header.num_apids = len(apid_info)
+    header.apid_list_offset = apid_list_offset
+    header.pkt_tracker_offset = pkt_tracker_offset
+    header.ap_storage_offset = ap_storage_offset
+    header.next_pkt_pos = total_pkt_size
+    header.start_boundary = granule_iet
+    header.end_boundary = granule_iet_end
+
+    for i, (apid, info) in enumerate(apid_info.items()):
+        offset = header.apid_list_offset + i * ctypes.sizeof(ApidListItem)
+        item = ApidListItem.from_buffer(buf, offset)
+        item.name = info['name']
+        item.value = apid
+        item.pkt_tracker_start_idx = info['first_tracker_index']
+        item.pkts_reserved = info['pkts_reserved']
+        item.pkts_received = info['pkts_received']
+
+        for j, pkt_info in enumerate(info['pkt_info']):
+            offset = (header.pkt_tracker_offset
+                      + (info['first_tracker_index'] + j) * ctypes.sizeof(PacketTracker))
+            tracker = PacketTracker.from_buffer(buf, offset)
+            if pkt_info:
+                tracker.obs_time = pkt_info['obs_time']
+                tracker.sequence_number = pkt_info['seq_num']
+                tracker.size = pkt_info['size']
+                tracker.offset = pkt_info['offset']
+                tracker.fill_percent = 0
+            else:
+                tracker.offset = -1
+
+    buf[ap_storage_offset:] = bytearray().join(pkt.bytes() for pkt in all_pkts)
+
+    return buf
+
+
+def get_cris_science_apids():
+    return ([ApidSpec(1289, 'EIGHT_S_SCI', 5), ApidSpec(1290, 'ENG', 1)]
+            + get_cris_obs_apids())
+
+
+def get_cris_obs_apids():
+    view_types = ['N', 'S', 'C']  # "normal", "space", "calibration"
+    bands = ['LW', 'MW', 'SW']
+    num_fovs = 9
+    base_apid = 1315
+    apids = []
+    for i in range(len(view_types) * len(bands) * num_fovs):
+        apid = base_apid + i
+        view_type = view_types[i // (num_fovs * len(bands))]
+        band = bands[i // num_fovs % len(bands)]
+        fov = str(i % num_fovs + 1)
+        apid_name = view_type + band + fov
+        max_expected = get_max_expected_cris_packets(apid_name)
+        apids.append(ApidSpec(apid, apid_name, max_expected))
+    return apids
+
+
+def get_max_expected_cris_packets(apid_name):
+    if apid_name == 'EIGHT_S_SCI':
+        return 5
+    elif apid_name == 'ENG':
+        return 1
+    else:
+        view_type = apid_name[0]
+        if view_type == 'N':
+            return 121
+        else:
+            return 9
+
+
+@attr.s
+class ApidSpec(object):
+    num = attr.ib()
+    name = attr.ib()
+    max_expected = attr.ib()
+
+
+class CrisScienceRdrType(object):
+    short_name = 'CRIS-SCIENCE-RDR'
+    granularity = 31997000
+    apids = get_cris_science_apids()
+    sensor = 'CrIS'
+    type_id = 'SCIENCE'
+
+
+def timecode_to_iet(timecode):
+    # FIXME: move to timecode.py
+    ccsds_epoch = iet_epoch = Time('1958-01-01', scale='tai')
+    day = Time(ccsds_epoch.jd + timecode.days, scale='utc', format='jd') - iet_epoch
+    return int(day.sec * 1e6 + timecode.milliseconds * 1e3 + timecode.microseconds)