from machine import Pin
from time import sleep

# Inputs
# D2, D1, D0 represent a 3-bit data word

D2_sw = Pin(18, Pin.IN)
D1_sw = Pin(19, Pin.IN)
D0_sw = Pin(21, Pin.IN)

# Outputs
temp_led = Pin(4, Pin.OUT)   # Shows TEMP = D2 XOR D1
parity_led = Pin(2, Pin.OUT) # Shows P = TEMP XOR D0

last_state = None

print("======================================")
print(" Even Parity Generator Lab")
print(" P = D2 XOR D1 XOR D0")
print("======================================")
print()
print("D2, D1, D0 = 3-bit data word")
print("P = even parity bit")
print()
print("If data has odd number of 1s, P = 1")
print("If data has even number of 1s, P = 0")
print()
print("D2 D1 D0 | TEMP | P | Total 1s with P")
print("--------------------------------------")

while True:
    D2 = D2_sw.value()
    D1 = D1_sw.value()
    D0 = D0_sw.value()

    # XOR chain
    TEMP = D2 ^ D1
    P = TEMP ^ D0

    temp_led.value(TEMP)
    parity_led.value(P)

    total_ones = D2 + D1 + D0 + P

    current_state = (D2, D1, D0, TEMP, P, total_ones)

    if current_state != last_state:
        print(D2, " ", D1, " ", D0, " |  ",
              TEMP, "   |", P, "|       ", total_ones)

        last_state = current_state

    sleep(0.1)