from machine import Pin
from time import sleep

# Inputs
P1 = Pin(18, Pin.IN)
P0 = Pin(19, Pin.IN)
Q1 = Pin(21, Pin.IN)
Q0 = Pin(22, Pin.IN)

# Outputs
msb_led = Pin(4, Pin.OUT)   # P1 XNOR Q1
lsb_led = Pin(5, Pin.OUT)   # P0 XNOR Q0
equal_led = Pin(2, Pin.OUT) # Final EQUAL

last_state = None

print("====================================")
print(" Two-Bit Equality Checker")
print(" EQUAL = XNOR(P1,Q1) AND XNOR(P0,Q0)")
print("====================================")
print()
print("P = P1P0")
print("Q = Q1Q0")
print()
print("Yellow LED = P1 matches Q1")
print("Blue LED   = P0 matches Q0")
print("Red LED    = Numbers Equal")
print()
print("P1 P0 Q1 Q0 | M1 M0 | EQUAL")
print("----------------------------")

while True:
    p1 = P1.value()
    p0 = P0.value()
    q1 = Q1.value()
    q0 = Q0.value()

    # XNOR = 1 when bits are same
    match1 = 1 if p1 == q1 else 0
    match0 = 1 if p0 == q0 else 0

    equal = match1 and match0

    msb_led.value(match1)
    lsb_led.value(match0)
    equal_led.value(int(equal))

    current = (p1, p0, q1, q0, match1, match0, int(equal))

    if current != last_state:
        print(p1, " ", p0, " ", q1, " ", q0,
              " | ", match1, " ", match0,
              " |   ", int(equal))
        last_state = current

    sleep(0.1)