brainfuck

brainfuck.py

from sys import argv
from terminedia import getch

MEMSIZE = 8192

def main():
    program = open(argv[1]).read()
    memory = bytearray(MEMSIZE)
    pointer = 0
    program_counter = 0
    while program_counter < len(program):
        opcode = program[program_counter]
        program_counter += 1
        if opcode in "\n \t\r":
            continue
        if opcode == ">": pointer += 1
        elif opcode == "<": pointer -= 1
        elif opcode == "+": memory[pointer] += 1
        elif opcode == "-": memory[pointer] -= 1
        elif opcode == ".": print(chr(memory[pointer]), end="", flush=True)
        elif opcode == ",": memory[pointer] = ord(getch())
        elif opcode == "D": print([int(m) for m in memory[:pointer + 10]])
        elif opcode == "[" and memory[pointer] == 0:
            open_brackets = 1
            future_pc = program_counter
            while open_brackets:
                if program[future_pc] == "[": open_brackets += 1
                elif program[future_pc] == "]": open_brackets -= 1
                future_pc += 1
                if future_pc >= len(program): raise RuntimeError()
            program_counter = future_pc + 1
        elif opcode == "]" and memory[pointer] != 0:
            open_brackets = 1
            future_pc = program_counter - 2
            while open_brackets:
                opcode = program[future_pc]
                if program[future_pc] == "]": open_brackets += 1
                elif program[future_pc] == "[": open_brackets -= 1
                future_pc -= 1
                if future_pc < 0: raise RuntimeError()
            program_counter = future_pc + 1

main()

echo_string.bf

+>+ # mark start of string
[<-> # decrease 1 on previous so mark is 0
,+ # input and inc to compensate for mark strategy
[>+>+<<-]>>[<<+>>-] # dup
++++++++++++++[<->-]<]+ # repeat while != 14 (cr plus 1)
[<]> # rewind up to last 0
[.>] # printstr