mbirth/gcd-parser
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Use new ChkSum class.

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This commit is contained in:
Markus Birth 2018-10-16 23:32:21 +02:00
parent cbb602ea83
commit 155d0e023c
Signed by: mbirth
GPG Key ID: A9928D7A098C3A9A
1 changed files with 7 additions and 12 deletions
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19
gcd.py
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@ -7,6 +7,7 @@ GCD_SIG = b"GARMINd\00"
from binascii import hexlify from binascii import hexlify
from struct import unpack from struct import unpack
from grmn import ChkSum
import sys import sys
FILE = sys.argv[1] FILE = sys.argv[1]
@ -33,18 +34,12 @@ DEV_TYPES = {
3196: "D2 Delta", 3196: "D2 Delta",
} }
running_cksum = 0 cksum = ChkSum()
all_cksum_ok = True all_cksum_ok = True
last_type6_fids = [] last_type6_fids = []
last_type6_format = "" last_type6_format = ""
last_type6_fields = [] last_type6_fields = []
def add_to_cksum(payload):
global running_cksum
for c in payload:
running_cksum += c
running_cksum &= 0xff
def get_tlv_comment(ttype): def get_tlv_comment(ttype):
if ttype in TLV_TYPES: if ttype in TLV_TYPES:
return TLV_TYPES[ttype] return TLV_TYPES[ttype]
@ -64,11 +59,11 @@ def parseTLVheader(hdr):
return (ttype, tlen) return (ttype, tlen)
def parseTLV1(payload): def parseTLV1(payload):
global running_cksum, all_cksum_ok global cksum, all_cksum_ok
if len(payload) != 1: if len(payload) != 1:
print(" ! Checksum has invalid length!") print(" ! Checksum has invalid length!")
all_cksum_ok = False all_cksum_ok = False
expected = ( 0x100 - running_cksum ) & 0xFF expected = cksum.get()
payload = unpack("B", payload)[0] payload = unpack("B", payload)[0]
state = "INVALID!" state = "INVALID!"
if expected == payload: if expected == payload:
@ -138,7 +133,7 @@ def parseTLV7(payload):
with open(FILE, "rb") as f: with open(FILE, "rb") as f:
sig = f.read(8) sig = f.read(8)
add_to_cksum(sig) cksum.add(sig)
if sig == GCD_SIG: if sig == GCD_SIG:
print("Signature ok.") print("Signature ok.")
else: else:
@ -150,7 +145,7 @@ with open(FILE, "rb") as f:
while True: while True:
hdr = f.read(4) hdr = f.read(4)
add_to_cksum(hdr) cksum.add(hdr)
(ttype, tlen) = parseTLVheader(hdr) (ttype, tlen) = parseTLVheader(hdr)
print("#{:04} TLV type {:04x} (offset 0x{:x}, length {} Bytes) - {}".format(i, ttype, f.tell(), tlen, get_tlv_comment(ttype))) print("#{:04} TLV type {:04x} (offset 0x{:x}, length {} Bytes) - {}".format(i, ttype, f.tell(), tlen, get_tlv_comment(ttype)))
if ttype == 0xFFFF: if ttype == 0xFFFF:
@ -176,7 +171,7 @@ with open(FILE, "rb") as f:
#print(" > " + " ".join("{:02x}".format(c) for c in payloadshort)) #print(" > " + " ".join("{:02x}".format(c) for c in payloadshort))
#print(hexlify(payload).decode("utf-8")) #print(hexlify(payload).decode("utf-8"))
#print(" > " + repr(payloadshort)) #print(" > " + repr(payloadshort))
add_to_cksum(payload) cksum.add(payload)
if ttype in [0x0008, 0x0401, 0x0505, 0x0555, 0x0557, 0x02bd]: if ttype in [0x0008, 0x0401, 0x0505, 0x0555, 0x0557, 0x02bd]:
outname = "{}_{:04x}.bin".format(FILE, ttype) outname = "{}_{:04x}.bin".format(FILE, ttype)
if ttype != cur_ttype: if ttype != cur_ttype: