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SMABluetoothPacket.py
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SMABluetoothPacket.py
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# GNU GENERAL PUBLIC LICENSE - Version 2, June 1991
# See LICENCE and README file for details
__author__ = 'Stuart Pittaway'
class SMABluetoothPacket:
def __str__(self):
return "I am an instance of SMABluetoothPacket"
def getLevel2Checksum(self):
return self.UnescapedArray[len(self.UnescapedArray) - 2] * 256 + self.UnescapedArray[len(self.UnescapedArray) - 3]
def lastByte(self):
return self.UnescapedArray[len(self.UnescapedArray) - 1]
def getLevel2Payload(self):
skipendbytes = 0
startbyte = 0
if self.UnescapedArray[0] == 0x7e:
startbyte = 1
if self.lastByte() == 0x7e:
skipendbytes = 3
# Skip the first 3 bytes, they are the command code 0x0001 and 0x7E start byte
# print "FirstByte={0:02x} LastByte={1:02x} startbyte={2} skipendbytes={3}".format(self.UnescapedArray[0],self.lastByte(),startbyte,skipendbytes)
l = len(self.UnescapedArray) - skipendbytes
# print "Copying array from {0} to {1}".format(startbyte,l)
# LogMessageWithByteArray("Copy Array", self.UnescapedArray[startbyte:l])
return self.UnescapedArray[startbyte:l]
def pushRawByteArray(self, barray):
# Raw byte array
for bte in barray: self.pushRawByte(bte)
def pushRawByte(self, value):
# Accept a byte of ESCAPED data (ie. raw byte from Bluetooth)
# //Store the raw byte
self.UnescapedArray.append(value)
self.RawByteArray.append(value)
def pushUnescapedByteArray(self, barray):
for bte in barray: self.pushUnescapedByte(bte)
def pushUnescapedByte(self, value):
# Store the raw byte
self.UnescapedArray.append(value)
if value == 0x7d or value == 0x7e or value == 0x11 or value == 0x12 or value == 0x13:
self.RawByteArray.append(0x7d) # byte to indicate escape character
self.RawByteArray.append(value ^ 0x20)
else:
self.RawByteArray.append(value)
def setChecksum(self):
self.header[3] = self.header[0] ^ self.header[1] ^ self.header[2]
def finish(self):
# Not seen any packets over 256 bytes, so zero second byte (needs to be fixed LOL!)
self.header[1] = len(self.RawByteArray) + self.headerlength
self.header[2] = 0
self.setChecksum()
# Just in case!
if self.ValidateHeaderChecksum() == False:
raise Exception("Invalid header checksum when finishing!")
def pushEscapedByte(self, value):
previousUnescapedByte = 0
if len(self.RawByteArray) > 0:
previousUnescapedByte = self.RawByteArray[ len(self.RawByteArray) - 1 ];
# Store the raw byte as it was received into RawByteArray
self.RawByteArray.append(value)
# did we receive the escape char in previous byte?
if (len(self.RawByteArray) > 0 and previousUnescapedByte == 0x7d):
# print "Escaped {0:02x} into {1:02x}".format(value,value ^ 0x20)
self.UnescapedArray[len(self.UnescapedArray) - 1] = value ^ 0x20
else:
# Unescaped array is same as raw array
self.UnescapedArray.append(value)
def sendPacket(self, btSocket):
m = bytearray(str(self.header) + str(self.SourceAddress) + str(self.DestinationAddress) + str(self.cmdcode) + str(self.RawByteArray))
# LogMessageWithByteArray("Send message", m)
l = btSocket.send(str(self.header) + str(self.SourceAddress) + str(self.DestinationAddress) + str(self.cmdcode) + str(self.RawByteArray))
# print "Sent message containing %d bytes" % l
# def DisplayPacketDebugInfo(self, Message):
# s = ""
# i = 0
# s += "[{0}] [{1}]\n".format(Message, "**RAW** Packet dump")
# s += " {0:08x}: {1:x} Header\n".format(i, self.header[i])
# i += 1
# s += " {0:08x}: {2:02x} {1:02x} Length\n".format(i, self.header[i], self.header[i + 1])
# i += 2
# s += " {0:08x}: {1:02x} Checksum\n".format(i, self.header[i])
# i += 1
# s += " {0:08x}: {6:02x}{5:02x}{4:02x}{3:02x}{2:02x}{1:02x} Source address\n".format(i, self.SourceAddress[0],
# self.SourceAddress[1],
# self.SourceAddress[2],
# self.SourceAddress[3],
# self.SourceAddress[4],
# self.SourceAddress[5])
# i += 6
# s += " {0:08x}: {6:02x}{5:02x}{4:02x}{3:02x}{2:02x}{1:02x} Destination address\n".format(i,
# self.DestinationAddress[
# 0],
# self.DestinationAddress[
# 1],
# self.DestinationAddress[
# 2],
# self.DestinationAddress[
# 3],
# self.DestinationAddress[
# 4],
# self.DestinationAddress[
# 5])
# i += 6
# s += " {0:08x}: {1:04x} Command\n".format(i, self.CommandCode())
# i += 2
#
# for j in range(0, len(self.RawByteArray)):
# if (j % 16 == 0):
# s += "\n %08x: " % j
#
# s += "%02x " % self.RawByteArray[j]
# i += 1
#
# s += "\n"
#
# if self.containsLevel2Packet():
# s += "*** LEVEL 2 PACKET IDENTIFIED ****\n"
#
# return s
def containsLevel2Packet(self):
if len(self.UnescapedArray) < 5:
return False
return (self.UnescapedArray[0] == 0x7e and
self.UnescapedArray[1] == 0xff and
self.UnescapedArray[2] == 0x03 and
self.UnescapedArray[3] == 0x60 and
self.UnescapedArray[4] == 0x65)
def CommandCode(self):
return self.cmdcode[0] + (self.cmdcode[1] * 256)
def setCommandCode(self, byteone, bytetwo):
self.cmdcode = bytearray([byteone, bytetwo])
def getByte(self, indexfromstartofdatapayload):
return self.UnescapedArray[indexfromstartofdatapayload]
def pushEscapedByteArray(self, barray):
for bte in barray: self.pushEscapedByte(bte)
def TotalUnescapedPacketLength(self):
return len(self.UnescapedArray) + self.headerlength
def TotalRawPacketLength(self):
return self.header[1] + (self.header[2] * 256)
def TotalPayloadLength(self):
return self.TotalRawPacketLength() - self.headerlength
def ValidateHeaderChecksum(self):
# Thanks to
# http://groups.google.com/group/sma-bluetooth/browse_thread/thread/50fe13a7c39bdce0/2caea56cdfb3a68a#2caea56cdfb3a68a
# for this checksum information !!
return (self.header[0] ^ self.header[1] ^ self.header[2] ^ self.header[3]) == 0
def __init__(self, length1, length2, checksum=0, cmd1=0, cmd2=0, SourceAddress=bytearray, DestinationAddress=bytearray()):
self.headerlength = 18
self.SourceAddress = SourceAddress
self.DestinationAddress = DestinationAddress
self.header = bytearray()
self.header.append(0x7e)
self.header.append(length1)
self.header.append(length2)
self.header.append(checksum)
# Create our array to hold the payload bytes
self.RawByteArray = bytearray()
self.UnescapedArray = bytearray()
self.setCommandCode(cmd1, cmd2)
if (checksum > 0) and (self.ValidateHeaderChecksum() == False):
raise Exception("Invalid header checksum!")
# print "SMABluetoothPacket class initiated"