assembler.py

instruction_set = {}
import string

def command( func ):
    def exec_(regbank, op, val = None ):
        if(val):
            pc = func(regbank, op, val)
        else:
            pc = func(regbank, op)
            
        if(not pc):
            next_pc = regbank["___PC___"] + 1
        else:
            next_pc = pc

        return next_pc
            
    instruction_set[func.__name__] = exec_    


@command
def mov(regbank, op, val):
    try:
        value = int(val)
    except:
        value = regbank[val]
    
    regbank[op] = value
    
@command
def inc(regbank, op ):
    regbank[op] += 1

@command
def dec(regbank, op ):
    regbank[op] += -1
    
@command
def jnz(regbank, op, val):
    try:
        value = int(op)
    except:
        value = regbank[op]

    if(value):
        next_pc = regbank["___PC___"] + int(val)
        return next_pc
  

def parse_instruction( str_ , regbank ):
    parsed = str_.split()

    if(len(parsed) == 2):
        parsed.append(None)
    
    inst, op, val = tuple(parsed)
    instruction = instruction_set[inst]

    def parsed_instruction():
        return instruction( regbank, op, val )

    return parsed_instruction

def parse_instructions(program, regbank):
    return [ parse_instruction(element, regbank) for element in program ]

def simple_assembler(program):
    
    regbank = {"___PC___": 0}    
    instruction_list = parse_instructions( program, regbank )

    pc = 0
    while( pc < len(instruction_list) ):
        pc = instruction_list[pc]()       
        regbank["___PC___"] = pc
        

    del regbank["___PC___"]

    return regbank

code = '''\
mov a 5
inc a
dec a
dec a
jnz a -1
inc a'''

print(simple_assembler(code.splitlines()))

code = '''\
mov c 12
mov b 0
mov a 200
dec a
inc b
jnz a -2
dec c
mov a b
jnz c -5
jnz 0 1
mov c a'''

print(simple_assembler(code.splitlines()))