Simple Brainfuck interpreter

bf.py

__author__ = 'davide'

import numpy as np

LEFT, RIGHT, INCR, DECR, INPUT, OUTPUT, WHILE, WEND = range(8)
opcodes = {'<': LEFT,
           '>': RIGHT,
           '+': INCR,
           '-': DECR,
           ',': INPUT,
           '.': OUTPUT,
           '[': WHILE,
           ']': WEND}


def assemble(code):
    assembled = []
    last_opened = []
    ip = 0
    for symbol in code:
        opcode = opcodes.get(symbol)
        if opcode is None:
            ip -= 1
        elif opcode == WHILE:
            last_opened.append(ip)
            assembled.append([WHILE, -1])
        elif opcode == WEND:
            last = last_opened.pop()
            assembled[last] = [WHILE, ip + 1]
            assembled.append([WEND, last + 1])
        else:
            assembled.append(opcode)
        ip += 1
    if last_opened:
        raise ValueError("Invalid code!")
    return assembled


def run(code, mem_size=3E4, debug=False):
    mem = np.zeros(mem_size, dtype=np.uint8)
    ip = 0
    mp = 0
    while ip < len(code):
        instr = code[ip]
        if instr == LEFT:
            mp = (mp + mem_size - 1) % mem_size
        elif instr == RIGHT:
            mp = (mp + 1) % mem_size
        elif instr == INCR:
            mem[mp] += 1
        elif instr == DECR:
            mem[mp] -= 1
        elif instr == INPUT:
            input_str = input() or "\0"
            mem[mp] = ord(input_str[0])
        elif instr == OUTPUT:
            print(chr(mem[mp]), end="")
        else:
            instr, jmp = instr
            if instr == WHILE:
                if not mem[mp]:
                    ip = jmp - 1
            elif instr == WEND:
                if mem[mp]:
                    ip = jmp - 1
        ip += 1
        if debug:
            print("IP: {}".format(ip))
            print("MP: {}".format(mp))
            print("MEM: {}".format(mem))