pythonによる小さな玩具VM

現実逃避したかったので、tinyvm.cなるプログラム(http://pastebin.com/f22e2c91)をpythonに移植した。

class Ins(object):

    def __init__(self, op, *arg):

        self.op, self.arg = op, arg

    def __repr__(self):

        return "%s(%s)" % (self.op.__name__, 

                           ','.join(map(str,

                                        filter(lambda x: x is not None,

                                               self.arg))))
class VM(object):

    def __init__(self, code):

        self.pc=0

        self.condpc=0

        self.register=[None]*4

        self.code=code
DONE=0

NOINC=1
def OP_HALT(mv, *args):

    return DONE

def OP_ADD(mv, reg, n):

    vm.register[reg]+=n

def OP_LOAD(mv, reg, value):

    vm.register[reg]=value

def OP_LOADW(mv, reg):

    vm.pc+=1

    assert isinstance(vm.code[vm.pc], int)

    vm.register[reg]=vm.code[vm.pc]

def OP_CNDPC(mv, pcv):

    vm.condpc=pcv

def OP_JMP(mv, pcv):

    vm.pc=pcv

    return NOINC

def OP_JMPEQ(mv, reg, value):

    if vm.register[reg]==value:

        vm.pc=vm.condpc

        return NOINC

def OP_JMPEQW(mv, reg):

    vm.pc+=1

    assert isinstance(vm.code[vm.pc], int)

    if vm.register[reg]==vm.code[vm.pc]:

        vm.pc=vm.condpc

        return NOINC

def OP_PRINT(mv, reg):

    print vm.register[reg]
if __name__=='__main__':
    REG_0=0
    code=[

        Ins(OP_CNDPC,	8),         # 0  condpc=8. set JMPEQW's dest.

        Ins(OP_LOADW,	REG_0),     # 1  reg[0]=0

        0,                          # 2  this---^ value

        Ins(OP_ADD, 	REG_0, 1),  # 3  reg[0]+=1

        Ins(OP_JMPEQW, 	REG_0),     # 4  if reg[0]==ins[pc+1]: pc=condpc

        10,                         # 5  this value ^^^^^^^^^

        Ins(OP_PRINT, 	REG_0),     # 6  print reg[0]

        Ins(OP_JMP, 	3),         # 7  goto #3

        Ins(OP_PRINT, 	REG_0),     # 8  print reg[0]

        Ins(OP_HALT),               # 9  exit()

        ]
    vm=VM(code)
    while True:

        ins=code[vm.pc]

        #print ins

        #print 'reg0=', vm.register[0]

        hoge=ins.op(vm, *ins.arg)

        if hoge==DONE:

            break

        elif hoge==NOINC:

            pass

        else:

            vm.pc+=1