Simplify code.

- defaultdict to avoid initialising every entry up front
- Use struct.calcsize instead of copying the values.
- if x == 0: y = False: else y = True => y = bool(x)
- list[len(list)-1] => list[-1]
- math.pow(256, 1) => 0x08 etc.
- x = bytearray(); x.append(y); x.append(z) => x = bytearray([y, z])
- value = x; return value => return x

src/emonhub.py

@@ -18,6 +18,7 @@
 import pprint
 import glob
 import os
+from collections import defaultdict
 
 import emonhub_setup as ehs
 import emonhub_coder as ehc
@@ -87,9 +88,7 @@ def run(self):
         signal.signal(signal.SIGINT, self._sigint_handler)
 
         # Initialise thread restart counters
-        restart_count = {}
-        for I in self._interfacers.itervalues():
-            restart_count[I.name] = 0
+        restart_count = defaultdict(int)
 
         # Until asked to stop
         while not self._exit:

src/emonhub_coder.py

@@ -5,15 +5,9 @@
 
 
 def check_datacode(datacode):
-    # Data types & sizes (number of bytes)
-    datacodes = {'b': '1', 'h': '2', 'i': '4', 'l': '4', 'q': '8', 'f': '4', 'd': '8',
-                 'B': '1', 'H': '2', 'I': '4', 'L': '4', 'Q': '8', 'c': '1', '?': '1'}
-
-    # if datacode is valid return the data size in bytes
-    if datacode in datacodes:
-        return int(datacodes[datacode])
-    # if not valid return False
-    else:
+    try:
+        return struct.calcsize(datacode)
+    except struct.error:
         return False
 
 
@@ -42,5 +36,4 @@ def encode(datacode, value):
 
     #value = 60
     #datacode = "b"
-    result = struct.unpack(e + b*s, struct.pack(e + datacode, value))
-    return result
+    return struct.unpack(e + b*s, struct.pack(e + datacode, value))

src/interfacers/EmonHubSMASolarInterfacer.py

@@ -36,15 +36,12 @@ def __init__(self, name, inverteraddress='', inverterpincode='0000', timeinverva
         self._port = 1
         self._nodeid = int(nodeid)
 
-        if packettrace == 0:
-            self._packettrace = False
-        else:
-            self._packettrace = True
+        self._packettrace = bool(packettrace)
 
         self.MySerialNumber = bytearray([0x08, 0x00, 0xaa, 0xbb, 0xcc, 0xdd])
 
         self._reset_packet_send_counter()
-        self._Inverters = None
+        self._Inverters = {}
         #Duration in seconds
         self._time_inverval = int(timeinverval)
         self._InverterPasswordArray = SMASolar_library.encodeInverterPassword(self._inverterpincode)

src/smalibrary/SMABluetoothPacket.py

@@ -8,10 +8,10 @@ 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]
+        return (self.UnescapedArray[-2] << 8) + self.UnescapedArray[-3]
 
     def lastByte(self):
-        return self.UnescapedArray[len(self.UnescapedArray) - 1]
+        return self.UnescapedArray[-1]
 
     def getLevel2Payload(self):
         skipendbytes = 0
@@ -23,9 +23,9 @@ def getLevel2Payload(self):
         if self.lastByte() == 0x7e:
             skipendbytes = 3
 
+        # FIXME This comment says to skip the first 3 bytes, but the code skips the *last* 3 bytes
         # Skip the first 3 bytes, they are the command code 0x0001 and 0x7E start byte
-        l = len(self.UnescapedArray) - skipendbytes
-        return self.UnescapedArray[startbyte:l]
+        return self.UnescapedArray[startbyte:-skipendbytes]
 
     def pushRawByteArray(self, barray):
         # Raw byte array
@@ -68,14 +68,14 @@ def pushEscapedByte(self, value):
         previousUnescapedByte = 0
 
         if len(self.RawByteArray) > 0:
-            previousUnescapedByte = self.RawByteArray[len(self.RawByteArray) - 1]
+            previousUnescapedByte = 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:
-            self.UnescapedArray[len(self.UnescapedArray) - 1] = value ^ 0x20
+            self.UnescapedArray[-1] = value ^ 0x20
         else:
             # Unescaped array is same as raw array
             self.UnescapedArray.append(value)
@@ -84,17 +84,15 @@ def sendPacket(self, btSocket):
         l = btSocket.send(str(self.header) + str(self.SourceAddress) + str(self.DestinationAddress) + str(self.cmdcode) + str(self.RawByteArray))
 
     def containsLevel2Packet(self):
-        if len(self.UnescapedArray) < 5:
-            return False
-
-        return (self.UnescapedArray[0] == 0x7e and
+        return (len(self.UnescapedArray) >= 5 and
+                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)
+        return self.cmdcode[0] + (self.cmdcode[1] << 8)
 
     def setCommandCode(self, byteone, bytetwo):
         self.cmdcode = bytearray([byteone, bytetwo])
@@ -110,7 +108,7 @@ def TotalUnescapedPacketLength(self):
         return len(self.UnescapedArray) + self.headerlength
 
     def TotalRawPacketLength(self):
-        return self.header[1] + (self.header[2] * 256)
+        return self.header[1] + (self.header[2] << 8)
 
     def TotalPayloadLength(self):
         return self.TotalRawPacketLength() - self.headerlength
@@ -126,11 +124,7 @@ def __init__(self, length1, length2, checksum=0, cmd1=0, cmd2=0, SourceAddress=b
         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)
+        self.header = bytearray([0x7e, length1, length2, checksum])
 
         # Create our array to hold the payload bytes
         self.RawByteArray = bytearray()

src/smalibrary/SMANET2PlusPacket.py

@@ -2,7 +2,6 @@
 # See LICENCE and README file for details
 
 import array
-import math
 try:
     from __builtin__ import long
 except ImportError:
@@ -86,26 +85,26 @@ def getByte(self, offset):
         return self.packet[offset]
 
     def getTwoByte(self, offset):
-        value = self.packet[offset] * math.pow(256, 0)
-        value += self.packet[offset + 1] * math.pow(256, 1)
+        value = self.packet[offset]
+        value += self.packet[offset + 1] << 8
         return long(value)
 
     def getFourByteLong(self, offset):
-        value = self.packet[offset] * math.pow(256, 0)
-        value += self.packet[offset + 1] * math.pow(256, 1)
-        value += self.packet[offset + 2] * math.pow(256, 2)
-        value += self.packet[offset + 3] * math.pow(256, 3)
+        value = self.packet[offset]
+        value += self.packet[offset + 1] << 0x08
+        value += self.packet[offset + 2] << 0x10
+        value += self.packet[offset + 3] << 0x18
         return long(value)
 
     def getEightByte(self, offset):
-        return self.packet[offset] * math.pow(256, 0) \
-                    + self.packet[offset + 1] * math.pow(256, 1) \
-                    + self.packet[offset + 2] * math.pow(256, 2) \
-                    + self.packet[offset + 3] * math.pow(256, 3) \
-                    + self.packet[offset + 4] * math.pow(256, 4) \
-                    + self.packet[offset + 5] * math.pow(256, 5) \
-                    + self.packet[offset + 6] * math.pow(256, 6) \
-                    + self.packet[offset + 7] * math.pow(256, 7)
+        return self.packet[offset] \
+                    + (self.packet[offset + 1] << 0x08) \
+                    + (self.packet[offset + 2] << 0x10) \
+                    + (self.packet[offset + 3] << 0x18) \
+                    + (self.packet[offset + 4] << 0x20) \
+                    + (self.packet[offset + 5] << 0x28) \
+                    + (self.packet[offset + 6] << 0x30) \
+                    + (self.packet[offset + 7] << 0x38)
 
     def getArray(self):
         return self.packet
@@ -139,8 +138,7 @@ def getFragment(self):
         return self.packet[24]
 
     def getTwoByteuShort(self, offset):
-        value = self.packet[offset] * math.pow(256, 0) + self.packet[offset + 1] * math.pow(256, 1)
-        return value
+        return self.packet[offset] + (self.packet[offset + 1] << 8)
 
     def errorCode(self):
         return self.getTwoByteuShort(22)
@@ -151,6 +149,7 @@ def calculateFCS(self):
             myfcs = (myfcs >> 8) ^ self.fcstab[(myfcs ^ bte) & 0xff]
 
         myfcs ^= 0xffff
+        return myfcs
 
     def pushByteArray(self, barray):
         for bte in barray: