1001-asm-imitator.py

# -*- coding: utf-8 -*-
import re
def remove_all(val, lst):  # dirty, simple and stupid
    for x in lst:
        if x == val: lst.remove(x)
    return lst
instructions = remove_all('', re.split('[\r|\n]', '''
 store a 1
 store b 2
add a 1
add     b -1
jlz 2
jmp -3
jmp 0
'''.lower()))
reg_file = {}    # register file: 装register的柜子。register: 登记簿
pc = 0    # pc: program counter
msb = 0 # most significat bit, 符号位
while True:
    i = instructions[pc] # fetch instruction 取指
    print('"' + i + '"', end='\t')
    pieces = remove_all('', i.split()) # 译码
    op_code = pieces[0] # op: operation
    if op_code == 'store':
        (reg_name, immd) = pieces[1:]
        reg_file[reg_name] = int(immd)
        pc += 1
    elif op_code == 'add':
        (reg_name, immd) = pieces[1:]
        reg_file[reg_name] += int(immd)
        if reg_file[reg_name] < 0: msb = 1
        pc += 1
    elif op_code == 'jlz': # jump if less than 0
        immd = int(pieces[1])
        if msb: pc += immd
        else: pc += 1
    elif op_code == 'jmp':
        immd = int(pieces[1])
        if immd == 0: break
        pc += immd
    print('\t', reg_file, ' pc=', pc, ' msb=', msb, sep='')
    input('Press the Enter key')

store b, 2也行——寄存器的名字叫B-逗号。注意b和b,是两个不同的寄存器。b和,之间不能有空格。

硬件实现呗：