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#!/usr/bin/env python2
#
# Decode EDI for debugging
import sys
import struct
from crc import crc16
class Printer:
def __init__(self):
self.indent = 0
def pr(self, s):
print(" " * self.indent + s)
def inc(self):
self.indent += 1
def dec(self):
self.indent -= 1
p = Printer()
def decode(stream):
p.pr("start")
success = False
pos = stream.tell()
sync = stream.read(2)
stream.seek(pos)
if len(sync) < 2:
p.pr("EOF")
return False
if sync == "PF":
if decode_pft(stream):
p.pr("PFT decode success")
success = True
else:
p.pr("PFT decode fail")
elif sync == "AF":
if decode_af(stream):
p.pr("AF decode success")
success = True
else:
p.pr("AF decode fail")
return success
pft_head_struct = "!2sH3B3BH"
pft_rs_head_struct = "!2B"
pft_addr_head_struct = "!2H"
def decode_pft(stream):
p.inc()
p.pr("start decoding PF")
headerdata = stream.read(12)
header = struct.unpack(pft_head_struct, headerdata)
psync, pseq, findex1, findex2, findex3, fcount1, fcount2, fcount3, fec_ad_plen = header
findex = (findex1 << 16) | (findex2 << 8) | findex3
fcount = (fcount1 << 16) | (fcount2 << 8) | fcount3
fec = (fec_ad_plen & 0x80) != 0x00
addr = (fec_ad_plen & 0x40) != 0x00
plen = fec_ad_plen & 0x3F
# try to sync according to TS 102 821 Clause 7.4.1
if psync != "PF":
p.pr("No PF Sync")
p.dec()
return False
rs_k = 0
rs_z = 0
if fec:
rs_head = stream.read(2)
rs_k, rs_z = struct.unpack(pft_rs_head_struct, rs_head)
headerdata += rs_head
addr_source = 0
addr_dest = 0
if addr:
addr_head = stream.read(4)
addr_source, addr_dest = struct.unpack(pft_addr_head_struct, addr_head)
headerdata += addr_head
# read CRC
headerdata += stream.read(2)
crc_ok = crc16(headerdata) == 0x1d0f
if crc_ok:
p.pr("CRC ok")
else:
p.pr("CRC not ok!")
p.pr("pseq {}".format(pseq))
p.pr("findex {}".format(findex))
p.pr("fcount {}".format(fcount))
if fec:
p.pr("with fec:")
p.pr(" RSk={}".format(rs_k))
p.pr(" RSz={}".format(rs_z))
if addr:
p.pr("with transport header:")
p.pr(" source={}".format(addr_source))
p.pr(" dest={}".format(addr_dest))
p.pr("payload length={}".format(plen))
success = False
if crc_ok and fec:
p.pr("RS PACKET TODO")
elif crc_ok:
success = decode_af(stream)
p.dec()
return success
af_head_struct = "!2sLHBc"
def decode_af(stream):
p.pr("AF Packet")
p.inc()
headerdata = stream.read(10)
sync, plen, seq, ar, pt = struct.unpack(af_head_struct, headerdata)
if sync != "AF":
p.pr("No AF Sync")
p.dec()
return False
crc_flag = (ar & 0x80) != 0x00
revision = ar & 0x7F
payload = stream.read(plen)
crc = struct.unpack("!H", stream.read(2))[0]
crc_calc = crc16(headerdata)
crc_calc = crc16(payload, crc_calc)
crc_calc ^= 0xFFFF
# manual endianness conversion
crc_calc = ((crc_calc >> 8) | (crc_calc << 8)) & 0xFFFF
crc_ok = crc_calc == crc
if crc_flag and crc_ok:
p.pr("CRC ok")
elif crc_flag:
p.pr("CRC not ok!")
p.pr(" CRC: is 0x{0:04x}, calculated 0x{1:04x}".format(crc, crc_calc))
else:
p.pr("No CRC")
p.pr("plen {}".format(plen))
p.pr("seq {}".format(seq))
p.pr("revision {}".format(revision))
p.pr("protocol type {}".format(pt))
success = False
if pt == "T":
success = decode_tag(payload)
p.dec()
return success
tag_item_head_struct = "!4sL"
def tagitems(tagpacket):
i = 0
while i+8 < len(tagpacket):
name, length = struct.unpack(tag_item_head_struct, tagpacket[i:i+8])
# length is in bits, because it's more annoying this way
assert(length % 8 == 0)
length /= 8
tag_value = tagpacket[i+8:i+8+length]
yield {'name': name, 'length': length, 'value': tag_value}
i += 8 + length
def decode_tag(tagpacket):
p.pr("Tag packet len={}".format(len(tagpacket)))
p.inc()
for item in tagitems(tagpacket):
if item['name'] == "deti":
decode_deti(item)
elif item['name'].startswith("est"):
decode_estn(item)
else:
p.pr("Tag item '{}' ({})".format(item['name'], item['length']))
p.dec()
return True
item_deti_header_struct = "!BBBBH"
def decode_deti(item):
p.pr("TAG item {} ({})".format(item['name'], item['length']))
p.inc()
tag_value = item['value']
unpacked = struct.unpack(item_deti_header_struct, tag_value[:6])
flag_fcth, fctl, stat, mid_fp, mnsc = unpacked
atstf = flag_fcth & 0x80 != 0
if atstf:
utco, seconds, tsta1, tsta2, tsta3 = struct.unpack("!BL3B", tag_value[6:6+8])
tsta = (tsta1 << 16) | (tsta2 << 8) | tsta3
ficf = flag_fcth & 0x40 != 0
rfudf = flag_fcth & 0x20 != 0
fcth = flag_fcth & 0x1F
fct = fcth << 5 | fctl
mid = (mid_fp >> 6) & 0x03
fp = (mid_fp >> 3) & 0x07
p.pr("FICF = {}".format(ficf))
p.pr("ATST = {}".format(atstf))
p.pr("RFUDF = {}".format(rfudf))
p.pr("FCT = {} (0x{:02x} 0x{:02x})".format(fct, fcth, fctl))
p.pr("STAT = 0x{:02x}".format(stat))
p.pr("Mode id = {}".format(mid))
p.pr("Frame phase = {}".format(fp))
p.pr("MNSC = 0x{:02x}".format(mnsc))
if atstf:
p.pr("UTCOffset = {}".format(utco))
p.pr("Seconds = {}".format(seconds))
p.pr("TSTA = {}".format(tsta))
len_fic = len(tag_value) - 2 - 4
if atstf:
len_fic -= 8
if rfudf:
len_fic -= 3
p.pr("FIC data len {}".format(len_fic))
p.dec()
item_estn_head_struct = "!HB"
def decode_estn(item):
estN = chr(ord("0") + ord(item['name'][3]))
p.pr("TAG item EST{} ({})".format(estN, item['length']))
p.inc()
tag_value = item['value']
scid_sad, tpl_rfa = struct.unpack(item_estn_head_struct, tag_value[:3])
scid = scid_sad >> 10
sad = scid_sad & 0x3F
tpl = tpl_rfa >> 2
p.pr("SCID = {}".format(scid))
p.pr("SAD = {}".format(sad))
p.pr("TPL = {}".format(tpl))
assert(item['length'] == len(tag_value))
p.pr("MST len = {}".format(len(tag_value) - 3))
p.dec()
if len(sys.argv) < 2:
print("Filename expected")
sys.exit(1)
filename = sys.argv[1]
edi_fd = open(filename, "r")
while decode(edi_fd):
pass
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