Adding two 4 digit binary numbers using adder circuits

Question

I need to write a program that adds two 4 digit binary numbers using an adder circuit that gives us an answer. I need to use the int() function to convert this from binary to decimal (both values need to be displayed). I am struggling to create a code that creates a correct binary AND decimal output. We're entering 2 sets of four digits. The digits are supposed to go through the circuit and the results should be them added together. Right now the gates are all good. But, I cannot get the digits to add together correctly. The binary addition through the circuit is incorrect. The converter and inputs are all correct.

The user needs to input a 4 digit binary number for x (x1,x2,x3,x4) and y (y1,y2,y3,y4), and ci = 0. For example: x = 1111 y = 0000

This is the adder circuit along with the diagram that shows how the circuit will look after adding the two binary numbers(I can't embed images yet)

this is my current code:

import string

print('Simple Circuits for Final Project')

x = input('x| enter 4 digits: ')
y = input('y| enter 4 digits: ')

list1 = list(x)
print(list1)

list2 = list(y)
print(list2)



#define all the gates
def xorgate(x,y):
    if x == y:
        return '0'
    else:
        return '1'

def andgate (x,y):
    if x == '1' and y == '1':
        return '1'
    else:
        return '0'

def orgate (x,y):
    if x == '1' or y == '1':
        return '1'
    else:
        return '0'

#define the entire circuit and input the list of inputs for the circuit.
#include the outputs based on the gates defined above.
def circuit(x,y,ci):
    a = 3 #starting value for the while loop, get approp position for our list
    adder = ['0','0','0','0','0']#adder list only has strings of zero. list to hold binary numbers from the output of the adding circuit
    b = 4
    while a >= 0:



        xorout = xorgate(x[a],y[a])
        print("xor:",(xorout))
        s = xorgate(ci,xorout)
        print("Ci:",ci)
        andout = andgate(xorout, ci)
        print("and1:",andout)
        and2out = andgate(x[a],y[a])
        print("and2:",and2out)
        co = orgate(andout,and2out)

        print('s:',s)
        print('co:',co)
        print('-----------------')

        ci = co
        adder[b] = str(s)
        a-=1
        b-=1


    adder[4]=ci
    #print(final)
    print('The Final Binary Output is:', adder[::-1])

    #OUR CONVERTER IS RIGHT, BUT WE CAN'T GET THE BINARY ADDITION ACCURATE
    outputfinal = ((int(adder[4]) * 16) + (int(adder[3]) * 8)+(int(adder[2]) * 4)+(int(adder[1]) * 2)+(int(adder[0]) * 1))
    print('The Final Decimal Output is:', outputfinal)
hold = '0'
circuit(list1,list2,hold)# 3 value for circuit

This is the part we feel is wrong:

    ci = co
    adder[b] = str(s)
    a-=1
    b-=1


adder[4]=ci
#print(final)
print('The Final Binary Output is:', adder[::-1])

This is how my current output is, which is wrong:

x| enter 4 digits: 1111
y| enter 4 digits: 0000
['1', '1', '1', '1']
['0', '0', '0', '0']
xor: 1
Ci: 0
and1: 0
and2: 0
s: 1
co: 0
-----------------
xor: 1
Ci: 0
and1: 0
and2: 0
s: 1
co: 0
-----------------
xor: 1
Ci: 0
and1: 0
and2: 0
s: 1
co: 0
-----------------
xor: 1
Ci: 0
and1: 0
and2: 0
s: 1
co: 0
-----------------
The Final Binary Output is: ['0', '1', '1', '1', '0']
The Final Decimal Output is: 14

Answer 1

You are confusing the order of your adder list.

It should be that first address is 0, not 4:

adder[0]=ci
#print(final)

Don't reverse the list yet

print('The Final Binary Output is:', adder)

Since your converter is expecting it to be in the opposite order, I reverse it here rather than rewrite your converter:

adder = adder[::-1]
#OUR CONVERTER IS RIGHT, BUT WE CAN'T GET THE BINARY ADDITION ACCURATE
outputfinal = ((int(adder[4]) * 16) + (int(adder[3]) * 8)+(int(adder[2]) * 4)+(int(adder[1]) * 2)+(int(adder[0]) * 1))
print('The Final Decimal Output is:', outputfinal)

You can try out the whole program (since you are getting a different result) in an online repl: https://repl.it/repls/CompetitiveSerpentineAccess