phy_serial: Some simple speed optimizations

Signed-off-by: Michael Buesch <m@bues.ch>

profisniff

@@ -3,7 +3,7 @@
 #
 # PROFIBUS - Telegram sniffer
 #
-# Copyright (c) 2016 Michael Buesch <m@bues.ch>
+# Copyright (c) 2016-2020 Michael Buesch <m@bues.ch>
 #
 # Licensed under the terms of the GNU General Public License version 2,
 # or (at your option) any later version.
@@ -12,6 +12,7 @@
 
 from pyprofibus.phy_serial import *
 from pyprofibus.fdl import *
+from pyprofibus import *
 
 import sys
 import getopt
@@ -55,7 +56,7 @@ def main():
 	try:
 		while True:
 			try:
-				ok, telegram = xceiv.poll(-1)
+				ok, telegram = xceiv.poll(-1.0)
 				if not ok or not telegram:
 					continue
 				print(telegram)

pyprofibus/dp.py

@@ -44,7 +44,7 @@ class DpTransceiver(object):
 		self.fdlTrans = fdlTrans
 		self.thisIsMaster = thisIsMaster
 
-	def poll(self, timeout = 0):
+	def poll(self, timeout=0.0):
 		retTelegram = None
 		ok, fdlTelegram = self.fdlTrans.poll(timeout)
 		if ok and fdlTelegram:

pyprofibus/fdl.py

@@ -107,7 +107,7 @@ class FdlTransceiver(object):
 		# Accept the packet, if it's in the RX filter.
 		return (telegram.da & FdlTelegram.ADDRESS_MASK) in self.__rxFilter
 
-	def poll(self, timeout=0):
+	def poll(self, timeout=0.0):
 		ok, telegram = False, None
 		reply = self.phy.poll(timeout)
 		if reply is not None:
@@ -205,6 +205,14 @@ class FdlTelegram(object):
 	FC_MRDY		= 0x20	# Master, ready to enter token ring
 	FC_MTR		= 0x30	# Master, in token ring
 
+	# Delimiter to size converstion table.
+	delim2size = {
+		SD1	: 6,
+		SD3	: 14,
+		SD4	: 3,
+		SC	: 1,
+	}
+
 	__slots__ = (
 		"sd",
 		"haveLE",
@@ -220,27 +228,22 @@ class FdlTelegram(object):
 
 	@classmethod
 	def getSizeFromRaw(cls, data):
-		try:
-			sd = data[0]
-			try:
-				return {
-					cls.SD1	: 6,
-					cls.SD3	: 14,
-					cls.SD4	: 3,
-					cls.SC	: 1,
-				}[sd]
-			except KeyError:
-				pass
-			if sd == cls.SD2:
-				le = data[1]
-				if data[2] != le:
-					raise FdlError("Repeated length field mismatch")
-				if le < 3 or le > 249:
-					raise FdlError("Invalid LE field")
-				return le + 6
-			raise FdlError("Unknown start delimiter: %02X" % sd)
-		except IndexError:
-			raise FdlError("Invalid FDL packet format")
+		dataLen = len(data)
+		if dataLen < 1:
+			return None # Telegram too short.
+		sd = data[0]
+		if sd in cls.delim2size:
+			return cls.delim2size[sd]
+		if sd == cls.SD2:
+			if dataLen < 3:
+				return None # Telegram too short.
+			le = data[1]
+			if data[2] != le:
+				return None # Repeated length field mismatch.
+			if le < 3 or le > 249:
+				return None # Invalid length field.
+			return le + 6
+		return None # Unknown start delimiter.
 
 	def __init__(self, sd, haveLE=False, da=None, sa=None,
 		     fc=None, dae=b"", sae=b"", du=None,

pyprofibus/phy.py

@@ -83,15 +83,15 @@ class CpPhy(object):
 	def pollData(self, timeout):
 		"""Poll received data from the physical line.
 		timeout => timeout in seconds.
-			   0 = no timeout, return immediately.
+			   0.0 = no timeout, return immediately.
 			   negative = unlimited.
 		Reimplement this method in the PHY driver.
 		"""
 		raise NotImplementedError
 
-	def poll(self, timeout = 0):
+	def poll(self, timeout=0.0):
 		"""timeout => timeout in seconds.
-			      0 = no timeout, return immediately.
+			      0.0 = no timeout, return immediately.
 			      negative = unlimited.
 		"""
 		if self.__txQueueDAs:

pyprofibus/phy_dummy.py

@@ -50,10 +50,10 @@ class CpPhyDummySlave(CpPhy):
 					       bytesToHex(telegramData)))
 		self.__mockSend(telegramData, srd = srd)
 
-	def pollData(self, timeout = 0):
+	def pollData(self, timeout=0.0):
 		"""Poll received data from the physical line.
 		timeout => timeout in seconds.
-			   0 = no timeout, return immediately.
+			   0.0 = no timeout, return immediately.
 			   negative = unlimited.
 		"""
 		try:

pyprofibus/phy_fpga.py

@@ -87,7 +87,7 @@ class CpPhyFPGA(CpPhy):
 			if self.__rxDeque:
 				telegramData = self.__rxDeque.popleft()
 			else:
-				timeoutStamp = monotonic_time() + timeout
+				timeoutStamp = monotonic_time() + timeout#TODO
 				telegramDataList = self.__driver.telegramReceive()
 				count = len(telegramDataList)
 				if count >= 1:

pyprofibus/phy_serial.py

@@ -107,49 +107,52 @@ class CpPhySerial(CpPhy):
 		self.__discardTimeout = monotonic_time() + 0.01
 
 	# Poll for received packet.
-	# timeout => In seconds. 0 = none, Negative = unlimited.
-	def pollData(self, timeout = 0):
-		timeoutStamp = monotonic_time() + timeout
-		ret, rxBuf, s, size = None, self.__rxBuf, self.__serial, -1
+	# timeout => In seconds. 0.0 = none, Negative = unlimited.
+	def pollData(self, timeout=0.0):
+		if timeout > 0.0:
+			timeoutStamp = monotonic_time() + timeout
+		ret = None
+		rxBuf = self.__rxBuf
+		ser = self.__serial
+		size = -1
 		getSize = FdlTelegram.getSizeFromRaw
 
 		if self.__discardTimeout is not None:
 			while self.__discardTimeout is not None:
 				self.__discard()
-				if timeout >= 0 and\
-				   monotonic_time() >= timeoutStamp:
+				if (timeout == 0.0 or
+				    (timeout > 0.0 and monotonic_time() >= timeoutStamp)):
 					return None
 
 		try:
+			rxBufLen = len(rxBuf)
 			while True:
-				if len(rxBuf) < 1:
-					rxBuf += s.read(1)
-				elif len(rxBuf) < 3:
-					try:
-						size = getSize(rxBuf)
-						readLen = size
-					except ProfibusError:
-						readLen = 3
-					rxBuf += s.read(readLen - len(rxBuf))
-				elif len(rxBuf) >= 3:
-					try:
-						size = getSize(rxBuf)
-					except ProfibusError:
+				if rxBufLen < 1:
+					rxBuf.extend(ser.read(1))
+				elif rxBufLen < 3:
+					size = getSize(rxBuf)
+					readLen = 3 if size is None else size
+					rxBuf.extend(ser.read(readLen - rxBufLen))
+				elif rxBufLen >= 3:
+					size = getSize(rxBuf)
+					if size is None:
 						rxBuf = bytearray()
 						self.__startDiscard()
 						raise PhyError("PHY-serial: "
-							"Failed to get received "
-							"telegram size:\n"
+							"Failed to get received telegram size: "
 							"Invalid telegram format.")
-					if len(rxBuf) < size:
-						rxBuf += s.read(size - len(rxBuf))
-
-				if len(rxBuf) == size:
-					ret, rxBuf = rxBuf, bytearray()
+					if rxBufLen < size:
+						rxBuf.extend(ser.read(size - rxBufLen))
+
+				rxBufLen = len(rxBuf)
+				if rxBufLen == size:
+					ret = rxBuf
+					rxBuf = bytearray()
+					rxBufLen = 0
 					break
 
-				if timeout >= 0 and\
-				   monotonic_time() >= timeoutStamp:
+				if (timeout == 0.0 or
+				    (timeout > 0.0 and monotonic_time() >= timeoutStamp)):
 					break
 		except serial.SerialException as e:
 			rxBuf = bytearray()
@@ -166,7 +169,6 @@ class CpPhySerial(CpPhy):
 		if self.__discardTimeout is not None:
 			return
 		try:
-			telegramData = bytearray(telegramData)
 			if self.debug:
 				print("PHY-serial: TX   %s" % bytesToHex(telegramData))
 			self.__serial.write(telegramData)