+++ /dev/null
-#!/usr/bin/env python
-# -*- coding: iso-8859-15 -*-
-
-import struct
-import threading
-import math
-from pycrc.crc_algorithms import Crc
-
-class ByteError(Exception):
- def __init__(self, value):
- Exception.__init__(self)
- self.value = value
- def __str__(self):
- return "Byte Error, got 0x%x" % self.value
-
-class CRCError(Exception):
- def __str__(self):
- return "CRC Error"
-
-class TimeoutException(Exception):
- def __str__(self):
- return "Timeout"
-
-class NAKReceived(Exception):
- def __str__(self):
- return "NAK received"
-
-class PackageTooBigException(Exception):
- def __str__(self):
- return "Package too long"
-
-
-class Protocoll:
- ENQ = 0x5
- ACK = 0x6
- DC1 = 0x11
- NAK = 0x21
- MAX_LEN = 128
- STATE_DEFAULT = 0
- STATE_LEN = 1
- STATE_READ = 2
-
- def __init__(self, conn):
- self.conn = conn
- self.lock = threading.Lock()
- self.crc = Crc(width = 8, poly = 0x07, reflect_in = False, xor_in = 0x0, reflect_out = False, xor_out = 0x00)
-
- def __get_ack(self):
- c = ""
- for i in range(60):
- try:
- c = self.conn.read(1)
- except:
- continue
- if c:
- break
- if not c:
- self.conn.close()
- raise TimeoutException()
- c = ord(c)
- if c not in (self.ACK, self.NAK):
- raise ByteError(c)
- return c == self.ACK
-
- def send(self, addr, msg, bSlitMsg=False):
- msg_len = 3 + len(msg) + 1
- if bSlitMsg and msg_len > self.MAX_LEN:
- num_per_packet = self.MAX_LEN - 3 - 1
- num_packets = math.ceil(len(msg)/float(num_per_packet))
- self.send(addr, "%cSplit %d" % (self.DC1, num_packets))
- for i in range(0, len(msg), num_per_packet):
- msg_part = msg[i:i+num_per_packet]
- self.send(addr, msg_part)
- return
- self.lock.acquire()
- try:
- if msg_len > self.MAX_LEN:
- raise PackageTooBigException()
- packet = struct.pack("<BBB%ds" % len(msg), self.ENQ, msg_len, addr, msg)
- packet+=chr(self.crc.bit_by_bit_fast(packet))
- self.conn.write(packet)
- if not self.__get_ack():
- raise NAKReceived()
- except:
- raise
- finally:
- self.lock.release()
-
- def write(self, addr, msg):
- return self.send(addr, msg)
-
- def __reply_ack(self):
- self.conn.write(chr(self.ACK))
-
- def __reply_nak(self):
- self.conn.write(chr(self.NAK))
-
- def receive(self):
- packet = ""
- num = 0
- state = self.STATE_DEFAULT
- self.lock.acquire()
- try:
- while(True):
- c = self.conn.read(1)
- if not c:
- raise
- if state == self.STATE_DEFAULT:
- if ord(c) != self.ENQ:
- self.__reply_nak()
- raise ByteError(ord(c))
- state = self.STATE_LEN
- packet = c
- elif state == self.STATE_LEN:
- if ord(c) > self.MAX_LEN:
- self.__reply_nak()
- raise PackageTooBigException()
- state = self.STATE_READ
- packet += c
- num = ord(c)-2
- elif state == self.STATE_READ:
- packet += c
- num-=1
- if num == 0:
- if self.crc.bit_by_bit_fast(packet) == 0:
- self.__reply_ack()
- msgtype, msglen, addr, msg, crc = struct.unpack("<BBB%dsB" % (len(packet)-3-1), packet)
- return addr, msg
- else:
- self.__reply_nak()
- raise CRCError()
- except:
- raise
- finally:
- self.lock.release()
-
- def read(self):
- addr, msg = self.receive()
- if msg[0] == chr(self.DC1) and len(msg) > 1:
- lCmd = msg[1:].split()
- if len(lCmd) == 2 and lCmd[0] == "Split":
- num = int(lCmd[1])
- msg = ""
- for i in range(num):
- addr_part, msg_part = self.receive()
- if addr_part == addr:
- msg+=msg_part
- return addr, msg
projects / pyshared.git / blobdiff