TrafficLight.py

# n7 n6 n5 n4 n3 n2 n1
# d3 d2 d1 p3 d1 p2 p1
'''
Send Message
|Trafficlight ID|Status |
'''
bitmap = { "r": 0b0001, "y": 0b0010, "g": 0b0100, "m": 0b1000 }
rbitmap = { 0b0001:"R",  0b0010:"Y", 0b0100:"G", 0b1000:"M" }

def encode_hamming4(msg):
    n3 = d1 = (msg >> 0) & 1
    n5 = d2 = (msg >> 1) & 1
    n6 = d3 = (msg >> 2) & 1
    n7 = d4 = (msg >> 3) & 1

    n1 = p1 = d1 ^ d2 ^ d4
    n2 = p2 = d1 ^ d3 ^ d4
    n4 = p3 = d2 ^ d3 ^ d4

    codeword = (n1 << 0) | (n2 << 1) | (n3 << 2) | (n4 << 3) | (n5 << 4) | (n6 << 5) | (n7 << 6)
    return codeword
    

def decode_hamming4(c):
   n1 = p1 = (c >> 0) & 1
   n2 = p2 = (c >> 1) & 1
   n3 = d1 = (c >> 2) & 1
   n4 = p3 = (c >> 3) & 1     
   n5 = d2 = (c >> 4) & 1
   n6 = d3 = (c >> 5) & 1
   n7 = d4 = (c >> 6) & 1

   c1 = p1 ^ d1 ^ d2 ^ d4
   c2 = p2 ^ d1 ^ d3 ^ d4   
   c3 = p3 ^ d2 ^ d3 ^ d4

   error_position = (c3 << 2) | (c2 << 1) | (c1 << 0)
   if error_position == 0:
         print("No error detected")       
   else:
        print("Error position:", error_position)

   match(error_position):
       case 0:
           pass
       case 1:
           n1 ^= 1
       case 2:
           n2 ^= 1
       case 3:
           n3 ^= 1
       case 4:
           n4 ^= 1
       case 5:
           n5 ^= 1
       case 6:
           n6 ^= 1
       case 7:
           n7 ^= 1

   decoded_msg = ((n7 << 3) | (n6 << 2) | (n5 << 1) | (n3 << 0))
   return decoded_msg

def encode(tl_id, state):
    enstate = str(encode_hamming4(bitmap[state.casefold()]))
    print(f"{tl_id}-{enstate}")

def decode(msg:str):
    tl_id, enstate = msg.split("-")
    enstate = int(enstate)
    state = decode_hamming4(enstate)
    print("Traffic Light ID:",tl_id)
    print("State:",rbitmap[state])

tl_id = input("Enter Traffic Light ID: ")
state = input("Enter State: ")

encode(tl_id,state)

testmg = "C2.F1.24-25"
decode(testmg)