--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/connectors/LPC/LPCProto.py	Tue Dec 01 13:48:47 2009 +0100
@@ -0,0 +1,88 @@
+import serial
+from threading import Lock
+
+LPC_CMDS=dict(IDLE = 0x00,
+              START = 0x01,
+              STOP = 0x02,
+              SET_TRACE_VARIABLE = 0x04,
+              GET_TRACE_VARIABLES = 0x05,
+              SET_FORCED_VARIABLE = 0x06,
+              GET_PLCID = 0x07)
+
+WAIT_DATA = 0x04
+
+LPC_STATUS=dict(STARTED = 0x01,
+                STOPPED = 0x02,
+                DEBUG = 0x03)
+
+class LPCError(exceptions.Exception):
+        """Exception class"""
+        def __init__(self, msg):
+                self.msg = msg
+                return
+
+        def __str__(self):
+                return "LPC communication error ! " + str(self.msg)
+
+class LPCProto:
+    def __init__(self, port, rate, timeout):
+        # open serial port
+        self.serialPort = serial.Serial( port, rate, timeout = timeout )
+        self.serialPort.flush()
+        # handshake
+        self.HandleTransaction(LPCTransaction("IDLE"))
+        # serialize access lock
+        self.TransactionLock = Lock()
+    
+    def HandleTransaction(self, transaction):
+        self.TransactionLock.acquire()
+        try:
+            transaction.SetPseudoFile(self.serialPort)
+            # send command, wait ack (timeout)
+            transaction.SendCommand()
+            current_plc_status = transaction.GetCommandAck()
+            if current_plc_status is not None:
+                res = transaction.ExchangeData()
+            else:
+                raise LPCError("LPC transaction error - controller did not answer as expected")
+        finally:
+            self.TransactionLock.release()
+        return current_plc_status, res
+    
+class LPCTransaction:
+    def __init__(self, command, optdata):
+        self.Command =  LPC_CMDS[command]
+        self.OptData = optdata[:]
+        self.serialPort = None
+        
+    def SetPseudoFile(pseudofile):
+        self.pseudofile = pseudofile
+        
+    def SendCommand(self):
+        # send command thread
+        self.pseudofile.write(chr(self.Command))
+        
+    def GetCommandAck(self):
+        comm_status, current_plc_status = map(ord, self.pseudofile.read(2))
+        # LPC returns command itself as an ack for command
+        if(comm_status == self.Command):
+            return current_plc_status
+        return None 
+        
+    def ExchangeData(self):
+        if self.Command & WAIT_DATA :
+            length = len(self.OptData)
+            # transform length into a byte string
+            # we presuppose endianess of LPC same as PC
+            lengthstr = ctypes.string_at(ctypes.pointer(ctypes.c_int(length)),4) 
+            self.pseudofile.write(lengthstr + self.OptData)
+            
+            lengthstr = self.pseudofile.read(4)
+            # transform a byte string into length 
+            length = ctypes.cast(ctypes.c_char_p(lengthstr), ctypes.POINTER(ctypes.c_int)).contents.value
+            return self.pseudofile.read(length)
+        return None
+        
+if __name__ == "__main__":
+    TestConnection = LPCProto()
+    
\ No newline at end of file