A stupid virtual machine.

vm.py

import enum

class Instruction(enum.Enum):
    HLT = 0 
    ADD = 1
    POP = 2
    PSH = 3
    SET = 4
    Get = 5
    JMP = 6


class CommonRegister(enum.Enum):
    A = 0
    B = 1
    C = 2
    D = 3

# instruction pointer of program variable
IP = 0

# the program instrution code to do what you want
program = [
    Instruction.PSH, 100,
    Instruction.PSH, 200,
    Instruction.ADD,
    Instruction.SET, CommonRegister.A,
    Instruction.Get, CommonRegister.A,
    Instruction.POP,
    Instruction.HLT,
]

# stack of the content
stack = []

register = {CommonRegister.A: 0, CommonRegister.B: 0, CommonRegister.C: 0, CommonRegister.D: 0}

runing = True

def loop():
    while runing:
        x = fetch()
        if x == Instruction.HLT:
            halt()
        elif x == Instruction.ADD:
            add()
        elif x == Instruction.POP:
            pop()
        elif x == Instruction.PSH:
            push()
        elif x == Instruction.SET:
            set_()
        elif x == Instruction.Get:
            get()
        elif x == Instruction.JMP:
            jump()
        else:
            raise Exception('Unknown instruction')


# fetch instruction and incr IP
def fetch():
    global IP, program
    r = program[IP]
    IP += 1
    return r
        

def halt():
    global runing
    runing = False


def add():
    global stack
    stack.append(stack.pop() + stack.pop())


def pop():
    global stack
    print(stack.pop())


def push():
    global stack
    stack.append(fetch())


def set_():
    global stack, register
    r = fetch()
    register[r] = stack.pop()


def get():
    global stack, register
    r = fetch()
    stack.append(register[r])


def jump():
    global IP
    IP = fetch()


if __name__ == "__main__":
    loop()