_ Git - youtube-dl/blob - youtube_dl/swfinterp.py

   1 from __future__ import unicode_literals
   2
   3 import collections
   4 import io
   5 import zlib
   6
   7 from .utils import (
   8     compat_str,
   9     ExtractorError,
  10     struct_unpack,
  11 )
  12
  13
  14 def _extract_tags(file_contents):
  15     if file_contents[1:3] != b'WS':
  16         raise ExtractorError(
  17             'Not an SWF file; header is %r' % file_contents[:3])
  18     if file_contents[:1] == b'C':
  19         content = zlib.decompress(file_contents[8:])
  20     else:
  21         raise NotImplementedError(
  22             'Unsupported compression format %r' %
  23             file_contents[:1])
  24
  25     # Determine number of bits in framesize rectangle
  26     framesize_nbits = struct_unpack('!B', content[:1])[0] >> 3
  27     framesize_len = (5 + 4 * framesize_nbits + 7) // 8
  28
  29     pos = framesize_len + 2 + 2
  30     while pos < len(content):
  31         header16 = struct_unpack('<H', content[pos:pos + 2])[0]
  32         pos += 2
  33         tag_code = header16 >> 6
  34         tag_len = header16 & 0x3f
  35         if tag_len == 0x3f:
  36             tag_len = struct_unpack('<I', content[pos:pos + 4])[0]
  37             pos += 4
  38         assert pos + tag_len <= len(content), \
  39             ('Tag %d ends at %d+%d - that\'s longer than the file (%d)'
  40                 % (tag_code, pos, tag_len, len(content)))
  41         yield (tag_code, content[pos:pos + tag_len])
  42         pos += tag_len
  43
  44
  45 class _AVMClass_Object(object):
  46     def __init__(self, avm_class):
  47         self.avm_class = avm_class
  48
  49     def __repr__(self):
  50         return '%s#%x' % (self.avm_class.name, id(self))
  51
  52
  53 class _ScopeDict(dict):
  54     def __init__(self, avm_class):
  55         super(_ScopeDict, self).__init__()
  56         self.avm_class = avm_class
  57
  58     def __repr__(self):
  59         return '%s__Scope(%s)' % (
  60             self.avm_class.name,
  61             super(_ScopeDict, self).__repr__())
  62
  63
  64 class _AVMClass(object):
  65     def __init__(self, name_idx, name):
  66         self.name_idx = name_idx
  67         self.name = name
  68         self.method_names = {}
  69         self.method_idxs = {}
  70         self.methods = {}
  71         self.method_pyfunctions = {}
  72
  73         self.variables = _ScopeDict(self)
  74         self.constants = {}
  75
  76     def make_object(self):
  77         return _AVMClass_Object(self)
  78
  79     def __repr__(self):
  80         return '_AVMClass(%s)' % (self.name)
  81
  82     def register_methods(self, methods):
  83         self.method_names.update(methods.items())
  84         self.method_idxs.update(dict(
  85             (idx, name)
  86             for name, idx in methods.items()))
  87
  88
  89 class _Multiname(object):
  90     def __init__(self, kind):
  91         self.kind = kind
  92
  93     def __repr__(self):
  94         return '[MULTINAME kind: 0x%x]' % self.kind
  95
  96
  97 def _read_int(reader):
  98     res = 0
  99     shift = 0
 100     for _ in range(5):
 101         buf = reader.read(1)
 102         assert len(buf) == 1
 103         b = struct_unpack('<B', buf)[0]
 104         res = res | ((b & 0x7f) << shift)
 105         if b & 0x80 == 0:
 106             break
 107         shift += 7
 108     return res
 109
 110
 111 def _u30(reader):
 112     res = _read_int(reader)
 113     assert res & 0xf0000000 == 0
 114     return res
 115 _u32 = _read_int
 116
 117
 118 def _s32(reader):
 119     v = _read_int(reader)
 120     if v & 0x80000000 != 0:
 121         v = - ((v ^ 0xffffffff) + 1)
 122     return v
 123
 124
 125 def _s24(reader):
 126     bs = reader.read(3)
 127     assert len(bs) == 3
 128     last_byte = b'\xff' if (ord(bs[2:3]) >= 0x80) else b'\x00'
 129     return struct_unpack('<i', bs + last_byte)[0]
 130
 131
 132 def _read_string(reader):
 133     slen = _u30(reader)
 134     resb = reader.read(slen)
 135     assert len(resb) == slen
 136     return resb.decode('utf-8')
 137
 138
 139 def _read_bytes(count, reader):
 140     assert count >= 0
 141     resb = reader.read(count)
 142     assert len(resb) == count
 143     return resb
 144
 145
 146 def _read_byte(reader):
 147     resb = _read_bytes(1, reader=reader)
 148     res = struct_unpack('<B', resb)[0]
 149     return res
 150
 151
 152 StringClass = _AVMClass('(no name idx)', 'String')
 153 ByteArrayClass = _AVMClass('(no name idx)', 'ByteArray')
 154 _builtin_classes = {
 155     StringClass.name: StringClass,
 156     ByteArrayClass.name: ByteArrayClass,
 157 }
 158
 159
 160 class _Undefined(object):
 161     def __boolean__(self):
 162         return False
 163
 164     def __hash__(self):
 165         return 0
 166
 167 undefined = _Undefined()
 168
 169
 170 class SWFInterpreter(object):
 171     def __init__(self, file_contents):
 172         self._patched_functions = {}
 173         code_tag = next(tag
 174                         for tag_code, tag in _extract_tags(file_contents)
 175                         if tag_code == 82)
 176         p = code_tag.index(b'\0', 4) + 1
 177         code_reader = io.BytesIO(code_tag[p:])
 178
 179         # Parse ABC (AVM2 ByteCode)
 180
 181         # Define a couple convenience methods
 182         u30 = lambda *args: _u30(*args, reader=code_reader)
 183         s32 = lambda *args: _s32(*args, reader=code_reader)
 184         u32 = lambda *args: _u32(*args, reader=code_reader)
 185         read_bytes = lambda *args: _read_bytes(*args, reader=code_reader)
 186         read_byte = lambda *args: _read_byte(*args, reader=code_reader)
 187
 188         # minor_version + major_version
 189         read_bytes(2 + 2)
 190
 191         # Constant pool
 192         int_count = u30()
 193         self.constant_ints = [0]
 194         for _c in range(1, int_count):
 195             self.constant_ints.append(s32())
 196         self.constant_uints = [0]
 197         uint_count = u30()
 198         for _c in range(1, uint_count):
 199             self.constant_uints.append(u32())
 200         double_count = u30()
 201         read_bytes(max(0, (double_count - 1)) * 8)
 202         string_count = u30()
 203         self.constant_strings = ['']
 204         for _c in range(1, string_count):
 205             s = _read_string(code_reader)
 206             self.constant_strings.append(s)
 207         namespace_count = u30()
 208         for _c in range(1, namespace_count):
 209             read_bytes(1)  # kind
 210             u30()  # name
 211         ns_set_count = u30()
 212         for _c in range(1, ns_set_count):
 213             count = u30()
 214             for _c2 in range(count):
 215                 u30()
 216         multiname_count = u30()
 217         MULTINAME_SIZES = {
 218             0x07: 2,  # QName
 219             0x0d: 2,  # QNameA
 220             0x0f: 1,  # RTQName
 221             0x10: 1,  # RTQNameA
 222             0x11: 0,  # RTQNameL
 223             0x12: 0,  # RTQNameLA
 224             0x09: 2,  # Multiname
 225             0x0e: 2,  # MultinameA
 226             0x1b: 1,  # MultinameL
 227             0x1c: 1,  # MultinameLA
 228         }
 229         self.multinames = ['']
 230         for _c in range(1, multiname_count):
 231             kind = u30()
 232             assert kind in MULTINAME_SIZES, 'Invalid multiname kind %r' % kind
 233             if kind == 0x07:
 234                 u30()  # namespace_idx
 235                 name_idx = u30()
 236                 self.multinames.append(self.constant_strings[name_idx])
 237             elif kind == 0x09:
 238                 name_idx = u30()
 239                 u30()
 240                 self.multinames.append(self.constant_strings[name_idx])
 241             else:
 242                 self.multinames.append(_Multiname(kind))
 243                 for _c2 in range(MULTINAME_SIZES[kind]):
 244                     u30()
 245
 246         # Methods
 247         method_count = u30()
 248         MethodInfo = collections.namedtuple(
 249             'MethodInfo',
 250             ['NEED_ARGUMENTS', 'NEED_REST'])
 251         method_infos = []
 252         for method_id in range(method_count):
 253             param_count = u30()
 254             u30()  # return type
 255             for _ in range(param_count):
 256                 u30()  # param type
 257             u30()  # name index (always 0 for youtube)
 258             flags = read_byte()
 259             if flags & 0x08 != 0:
 260                 # Options present
 261                 option_count = u30()
 262                 for c in range(option_count):
 263                     u30()  # val
 264                     read_bytes(1)  # kind
 265             if flags & 0x80 != 0:
 266                 # Param names present
 267                 for _ in range(param_count):
 268                     u30()  # param name
 269             mi = MethodInfo(flags & 0x01 != 0, flags & 0x04 != 0)
 270             method_infos.append(mi)
 271
 272         # Metadata
 273         metadata_count = u30()
 274         for _c in range(metadata_count):
 275             u30()  # name
 276             item_count = u30()
 277             for _c2 in range(item_count):
 278                 u30()  # key
 279                 u30()  # value
 280
 281         def parse_traits_info():
 282             trait_name_idx = u30()
 283             kind_full = read_byte()
 284             kind = kind_full & 0x0f
 285             attrs = kind_full >> 4
 286             methods = {}
 287             constants = None
 288             if kind == 0x00:  # Slot
 289                 u30()  # Slot id
 290                 u30()  # type_name_idx
 291                 vindex = u30()
 292                 if vindex != 0:
 293                     read_byte()  # vkind
 294             elif kind == 0x06:  # Const
 295                 u30()  # Slot id
 296                 u30()  # type_name_idx
 297                 vindex = u30()
 298                 vkind = 'any'
 299                 if vindex != 0:
 300                     vkind = read_byte()
 301                 if vkind == 0x03:  # Constant_Int
 302                     value = self.constant_ints[vindex]
 303                 elif vkind == 0x04:  # Constant_UInt
 304                     value = self.constant_uints[vindex]
 305                 else:
 306                     return {}, None  # Ignore silently for now
 307                 constants = {self.multinames[trait_name_idx]: value}
 308             elif kind in (0x01, 0x02, 0x03):  # Method / Getter / Setter
 309                 u30()  # disp_id
 310                 method_idx = u30()
 311                 methods[self.multinames[trait_name_idx]] = method_idx
 312             elif kind == 0x04:  # Class
 313                 u30()  # slot_id
 314                 u30()  # classi
 315             elif kind == 0x05:  # Function
 316                 u30()  # slot_id
 317                 function_idx = u30()
 318                 methods[function_idx] = self.multinames[trait_name_idx]
 319             else:
 320                 raise ExtractorError('Unsupported trait kind %d' % kind)
 321
 322             if attrs & 0x4 != 0:  # Metadata present
 323                 metadata_count = u30()
 324                 for _c3 in range(metadata_count):
 325                     u30()  # metadata index
 326
 327             return methods, constants
 328
 329         # Classes
 330         class_count = u30()
 331         classes = []
 332         for class_id in range(class_count):
 333             name_idx = u30()
 334
 335             cname = self.multinames[name_idx]
 336             avm_class = _AVMClass(name_idx, cname)
 337             classes.append(avm_class)
 338
 339             u30()  # super_name idx
 340             flags = read_byte()
 341             if flags & 0x08 != 0:  # Protected namespace is present
 342                 u30()  # protected_ns_idx
 343             intrf_count = u30()
 344             for _c2 in range(intrf_count):
 345                 u30()
 346             u30()  # iinit
 347             trait_count = u30()
 348             for _c2 in range(trait_count):
 349                 trait_methods, constants = parse_traits_info()
 350                 avm_class.register_methods(trait_methods)
 351                 assert constants is None
 352
 353         assert len(classes) == class_count
 354         self._classes_by_name = dict((c.name, c) for c in classes)
 355
 356         for avm_class in classes:
 357             u30()  # cinit
 358             trait_count = u30()
 359             for _c2 in range(trait_count):
 360                 trait_methods, trait_constants = parse_traits_info()
 361                 avm_class.register_methods(trait_methods)
 362                 if trait_constants:
 363                     avm_class.constants.update(trait_constants)
 364
 365         # Scripts
 366         script_count = u30()
 367         for _c in range(script_count):
 368             u30()  # init
 369             trait_count = u30()
 370             for _c2 in range(trait_count):
 371                 parse_traits_info()
 372
 373         # Method bodies
 374         method_body_count = u30()
 375         Method = collections.namedtuple('Method', ['code', 'local_count'])
 376         for _c in range(method_body_count):
 377             method_idx = u30()
 378             u30()  # max_stack
 379             local_count = u30()
 380             u30()  # init_scope_depth
 381             u30()  # max_scope_depth
 382             code_length = u30()
 383             code = read_bytes(code_length)
 384             for avm_class in classes:
 385                 if method_idx in avm_class.method_idxs:
 386                     m = Method(code, local_count)
 387                     avm_class.methods[avm_class.method_idxs[method_idx]] = m
 388             exception_count = u30()
 389             for _c2 in range(exception_count):
 390                 u30()  # from
 391                 u30()  # to
 392                 u30()  # target
 393                 u30()  # exc_type
 394                 u30()  # var_name
 395             trait_count = u30()
 396             for _c2 in range(trait_count):
 397                 parse_traits_info()
 398
 399         assert p + code_reader.tell() == len(code_tag)
 400
 401     def patch_function(self, avm_class, func_name, f):
 402         self._patched_functions[(avm_class, func_name)] = f
 403
 404     def extract_class(self, class_name):
 405         try:
 406             return self._classes_by_name[class_name]
 407         except KeyError:
 408             raise ExtractorError('Class %r not found' % class_name)
 409
 410     def extract_function(self, avm_class, func_name):
 411         p = self._patched_functions.get((avm_class, func_name))
 412         if p:
 413             return p
 414         if func_name in avm_class.method_pyfunctions:
 415             return avm_class.method_pyfunctions[func_name]
 416         if func_name in self._classes_by_name:
 417             return self._classes_by_name[func_name].make_object()
 418         if func_name not in avm_class.methods:
 419             raise ExtractorError('Cannot find function %s.%s' % (
 420                 avm_class.name, func_name))
 421         m = avm_class.methods[func_name]
 422
 423         def resfunc(args):
 424             # Helper functions
 425             coder = io.BytesIO(m.code)
 426             s24 = lambda: _s24(coder)
 427             u30 = lambda: _u30(coder)
 428
 429             registers = [avm_class.variables] + list(args) + [None] * m.local_count
 430             stack = []
 431             scopes = collections.deque([
 432                 self._classes_by_name, avm_class.variables])
 433             while True:
 434                 opcode = _read_byte(coder)
 435                 if opcode == 9:  # label
 436                     pass  # Spec says: "Do nothing."
 437                 elif opcode == 16:  # jump
 438                     offset = s24()
 439                     coder.seek(coder.tell() + offset)
 440                 elif opcode == 17:  # iftrue
 441                     offset = s24()
 442                     value = stack.pop()
 443                     if value:
 444                         coder.seek(coder.tell() + offset)
 445                 elif opcode == 18:  # iffalse
 446                     offset = s24()
 447                     value = stack.pop()
 448                     if not value:
 449                         coder.seek(coder.tell() + offset)
 450                 elif opcode == 19:  # ifeq
 451                     offset = s24()
 452                     value2 = stack.pop()
 453                     value1 = stack.pop()
 454                     if value2 == value1:
 455                         coder.seek(coder.tell() + offset)
 456                 elif opcode == 20:  # ifne
 457                     offset = s24()
 458                     value2 = stack.pop()
 459                     value1 = stack.pop()
 460                     if value2 != value1:
 461                         coder.seek(coder.tell() + offset)
 462                 elif opcode == 21:  # iflt
 463                     offset = s24()
 464                     value2 = stack.pop()
 465                     value1 = stack.pop()
 466                     if value1 < value2:
 467                         coder.seek(coder.tell() + offset)
 468                 elif opcode == 32:  # pushnull
 469                     stack.append(None)
 470                 elif opcode == 33:  # pushundefined
 471                     stack.append(undefined)
 472                 elif opcode == 36:  # pushbyte
 473                     v = _read_byte(coder)
 474                     stack.append(v)
 475                 elif opcode == 37:  # pushshort
 476                     v = u30()
 477                     stack.append(v)
 478                 elif opcode == 38:  # pushtrue
 479                     stack.append(True)
 480                 elif opcode == 39:  # pushfalse
 481                     stack.append(False)
 482                 elif opcode == 40:  # pushnan
 483                     stack.append(float('NaN'))
 484                 elif opcode == 42:  # dup
 485                     value = stack[-1]
 486                     stack.append(value)
 487                 elif opcode == 44:  # pushstring
 488                     idx = u30()
 489                     stack.append(self.constant_strings[idx])
 490                 elif opcode == 48:  # pushscope
 491                     new_scope = stack.pop()
 492                     scopes.append(new_scope)
 493                 elif opcode == 66:  # construct
 494                     arg_count = u30()
 495                     args = list(reversed(
 496                         [stack.pop() for _ in range(arg_count)]))
 497                     obj = stack.pop()
 498                     res = obj.avm_class.make_object()
 499                     stack.append(res)
 500                 elif opcode == 70:  # callproperty
 501                     index = u30()
 502                     mname = self.multinames[index]
 503                     arg_count = u30()
 504                     args = list(reversed(
 505                         [stack.pop() for _ in range(arg_count)]))
 506                     obj = stack.pop()
 507
 508                     if obj == StringClass:
 509                         if mname == 'String':
 510                             assert len(args) == 1
 511                             assert isinstance(args[0], (
 512                                 int, compat_str, _Undefined))
 513                             if args[0] == undefined:
 514                                 res = 'undefined'
 515                             else:
 516                                 res = compat_str(args[0])
 517                             stack.append(res)
 518                             continue
 519                         else:
 520                             raise NotImplementedError(
 521                                 'Function String.%s is not yet implemented'
 522                                 % mname)
 523                     elif isinstance(obj, _AVMClass_Object):
 524                         func = self.extract_function(obj.avm_class, mname)
 525                         res = func(args)
 526                         stack.append(res)
 527                         continue
 528                     elif isinstance(obj, _AVMClass):
 529                         func = self.extract_function(obj, mname)
 530                         res = func(args)
 531                         stack.append(res)
 532                         continue
 533                     elif isinstance(obj, _ScopeDict):
 534                         if mname in obj.avm_class.method_names:
 535                             func = self.extract_function(obj.avm_class, mname)
 536                             res = func(args)
 537                         else:
 538                             res = obj[mname]
 539                         stack.append(res)
 540                         continue
 541                     elif isinstance(obj, compat_str):
 542                         if mname == 'split':
 543                             assert len(args) == 1
 544                             assert isinstance(args[0], compat_str)
 545                             if args[0] == '':
 546                                 res = list(obj)
 547                             else:
 548                                 res = obj.split(args[0])
 549                             stack.append(res)
 550                             continue
 551                         elif mname == 'charCodeAt':
 552                             assert len(args) <= 1
 553                             idx = 0 if len(args) == 0 else args[0]
 554                             assert isinstance(idx, int)
 555                             res = ord(obj[idx])
 556                             stack.append(res)
 557                             continue
 558                     elif isinstance(obj, list):
 559                         if mname == 'slice':
 560                             assert len(args) == 1
 561                             assert isinstance(args[0], int)
 562                             res = obj[args[0]:]
 563                             stack.append(res)
 564                             continue
 565                         elif mname == 'join':
 566                             assert len(args) == 1
 567                             assert isinstance(args[0], compat_str)
 568                             res = args[0].join(obj)
 569                             stack.append(res)
 570                             continue
 571                     raise NotImplementedError(
 572                         'Unsupported property %r on %r'
 573                         % (mname, obj))
 574                 elif opcode == 71:  # returnvoid
 575                     res = undefined
 576                     return res
 577                 elif opcode == 72:  # returnvalue
 578                     res = stack.pop()
 579                     return res
 580                 elif opcode == 74:  # constructproperty
 581                     index = u30()
 582                     arg_count = u30()
 583                     args = list(reversed(
 584                         [stack.pop() for _ in range(arg_count)]))
 585                     obj = stack.pop()
 586
 587                     mname = self.multinames[index]
 588                     assert isinstance(obj, _AVMClass)
 589
 590                     # We do not actually call the constructor for now;
 591                     # we just pretend it does nothing
 592                     stack.append(obj.make_object())
 593                 elif opcode == 79:  # callpropvoid
 594                     index = u30()
 595                     mname = self.multinames[index]
 596                     arg_count = u30()
 597                     args = list(reversed(
 598                         [stack.pop() for _ in range(arg_count)]))
 599                     obj = stack.pop()
 600                     if isinstance(obj, _AVMClass_Object):
 601                         func = self.extract_function(obj.avm_class, mname)
 602                         res = func(args)
 603                         assert res is undefined
 604                         continue
 605                     if isinstance(obj, _ScopeDict):
 606                         assert mname in obj.avm_class.method_names
 607                         func = self.extract_function(obj.avm_class, mname)
 608                         res = func(args)
 609                         assert res is undefined
 610                         continue
 611                     if mname == 'reverse':
 612                         assert isinstance(obj, list)
 613                         obj.reverse()
 614                     else:
 615                         raise NotImplementedError(
 616                             'Unsupported (void) property %r on %r'
 617                             % (mname, obj))
 618                 elif opcode == 86:  # newarray
 619                     arg_count = u30()
 620                     arr = []
 621                     for i in range(arg_count):
 622                         arr.append(stack.pop())
 623                     arr = arr[::-1]
 624                     stack.append(arr)
 625                 elif opcode == 93:  # findpropstrict
 626                     index = u30()
 627                     mname = self.multinames[index]
 628                     for s in reversed(scopes):
 629                         if mname in s:
 630                             res = s
 631                             break
 632                     else:
 633                         res = scopes[0]
 634                     if mname not in res and mname in _builtin_classes:
 635                         stack.append(_builtin_classes[mname])
 636                     else:
 637                         stack.append(res[mname])
 638                 elif opcode == 94:  # findproperty
 639                     index = u30()
 640                     mname = self.multinames[index]
 641                     for s in reversed(scopes):
 642                         if mname in s:
 643                             res = s
 644                             break
 645                     else:
 646                         res = avm_class.variables
 647                     stack.append(res)
 648                 elif opcode == 96:  # getlex
 649                     index = u30()
 650                     mname = self.multinames[index]
 651                     for s in reversed(scopes):
 652                         if mname in s:
 653                             scope = s
 654                             break
 655                     else:
 656                         scope = avm_class.variables
 657
 658                     if mname in scope:
 659                         res = scope[mname]
 660                     else:
 661                         res = avm_class.constants[mname]
 662                     stack.append(res)
 663                 elif opcode == 97:  # setproperty
 664                     index = u30()
 665                     value = stack.pop()
 666                     idx = self.multinames[index]
 667                     if isinstance(idx, _Multiname):
 668                         idx = stack.pop()
 669                     obj = stack.pop()
 670                     obj[idx] = value
 671                 elif opcode == 98:  # getlocal
 672                     index = u30()
 673                     stack.append(registers[index])
 674                 elif opcode == 99:  # setlocal
 675                     index = u30()
 676                     value = stack.pop()
 677                     registers[index] = value
 678                 elif opcode == 102:  # getproperty
 679                     index = u30()
 680                     pname = self.multinames[index]
 681                     if pname == 'length':
 682                         obj = stack.pop()
 683                         assert isinstance(obj, (compat_str, list))
 684                         stack.append(len(obj))
 685                     elif isinstance(pname, compat_str):  # Member access
 686                         obj = stack.pop()
 687                         assert isinstance(obj, (dict, _ScopeDict)), \
 688                             'Accessing member %r on %r' % (pname, obj)
 689                         res = obj.get(pname, undefined)
 690                         stack.append(res)
 691                     else:  # Assume attribute access
 692                         idx = stack.pop()
 693                         assert isinstance(idx, int)
 694                         obj = stack.pop()
 695                         assert isinstance(obj, list)
 696                         stack.append(obj[idx])
 697                 elif opcode == 115:  # convert_
 698                     value = stack.pop()
 699                     intvalue = int(value)
 700                     stack.append(intvalue)
 701                 elif opcode == 128:  # coerce
 702                     u30()
 703                 elif opcode == 130:  # coerce_a
 704                     value = stack.pop()
 705                     # um, yes, it's any value
 706                     stack.append(value)
 707                 elif opcode == 133:  # coerce_s
 708                     assert isinstance(stack[-1], (type(None), compat_str))
 709                 elif opcode == 147:  # decrement
 710                     value = stack.pop()
 711                     assert isinstance(value, int)
 712                     stack.append(value - 1)
 713                 elif opcode == 149:  # typeof
 714                     value = stack.pop()
 715                     return {
 716                         _Undefined: 'undefined',
 717                         compat_str: 'String',
 718                         int: 'Number',
 719                         float: 'Number',
 720                     }[type(value)]
 721                 elif opcode == 160:  # add
 722                     value2 = stack.pop()
 723                     value1 = stack.pop()
 724                     res = value1 + value2
 725                     stack.append(res)
 726                 elif opcode == 161:  # subtract
 727                     value2 = stack.pop()
 728                     value1 = stack.pop()
 729                     res = value1 - value2
 730                     stack.append(res)
 731                 elif opcode == 162:  # multiply
 732                     value2 = stack.pop()
 733                     value1 = stack.pop()
 734                     res = value1 * value2
 735                     stack.append(res)
 736                 elif opcode == 164:  # modulo
 737                     value2 = stack.pop()
 738                     value1 = stack.pop()
 739                     res = value1 % value2
 740                     stack.append(res)
 741                 elif opcode == 168:  # bitand
 742                     value2 = stack.pop()
 743                     value1 = stack.pop()
 744                     assert isinstance(value1, int)
 745                     assert isinstance(value2, int)
 746                     res = value1 & value2
 747                     stack.append(res)
 748                 elif opcode == 171:  # equals
 749                     value2 = stack.pop()
 750                     value1 = stack.pop()
 751                     result = value1 == value2
 752                     stack.append(result)
 753                 elif opcode == 175:  # greaterequals
 754                     value2 = stack.pop()
 755                     value1 = stack.pop()
 756                     result = value1 >= value2
 757                     stack.append(result)
 758                 elif opcode == 192:  # increment_i
 759                     value = stack.pop()
 760                     assert isinstance(value, int)
 761                     stack.append(value + 1)
 762                 elif opcode == 208:  # getlocal_0
 763                     stack.append(registers[0])
 764                 elif opcode == 209:  # getlocal_1
 765                     stack.append(registers[1])
 766                 elif opcode == 210:  # getlocal_2
 767                     stack.append(registers[2])
 768                 elif opcode == 211:  # getlocal_3
 769                     stack.append(registers[3])
 770                 elif opcode == 212:  # setlocal_0
 771                     registers[0] = stack.pop()
 772                 elif opcode == 213:  # setlocal_1
 773                     registers[1] = stack.pop()
 774                 elif opcode == 214:  # setlocal_2
 775                     registers[2] = stack.pop()
 776                 elif opcode == 215:  # setlocal_3
 777                     registers[3] = stack.pop()
 778                 else:
 779                     raise NotImplementedError(
 780                         'Unsupported opcode %d' % opcode)
 781
 782         avm_class.method_pyfunctions[func_name] = resfunc
 783         return resfunc
 784