release 2018.10.05
[ytdl] / youtube_dl / swfinterp.py
1 from __future__ import unicode_literals
2
3 import collections
4 import io
5 import zlib
6
7 from .compat import (
8     compat_str,
9     compat_struct_unpack,
10 )
11 from .utils import (
12     ExtractorError,
13 )
14
15
16 def _extract_tags(file_contents):
17     if file_contents[1:3] != b'WS':
18         raise ExtractorError(
19             'Not an SWF file; header is %r' % file_contents[:3])
20     if file_contents[:1] == b'C':
21         content = zlib.decompress(file_contents[8:])
22     else:
23         raise NotImplementedError(
24             'Unsupported compression format %r' %
25             file_contents[:1])
26
27     # Determine number of bits in framesize rectangle
28     framesize_nbits = compat_struct_unpack('!B', content[:1])[0] >> 3
29     framesize_len = (5 + 4 * framesize_nbits + 7) // 8
30
31     pos = framesize_len + 2 + 2
32     while pos < len(content):
33         header16 = compat_struct_unpack('<H', content[pos:pos + 2])[0]
34         pos += 2
35         tag_code = header16 >> 6
36         tag_len = header16 & 0x3f
37         if tag_len == 0x3f:
38             tag_len = compat_struct_unpack('<I', content[pos:pos + 4])[0]
39             pos += 4
40         assert pos + tag_len <= len(content), \
41             ('Tag %d ends at %d+%d - that\'s longer than the file (%d)'
42                 % (tag_code, pos, tag_len, len(content)))
43         yield (tag_code, content[pos:pos + tag_len])
44         pos += tag_len
45
46
47 class _AVMClass_Object(object):
48     def __init__(self, avm_class):
49         self.avm_class = avm_class
50
51     def __repr__(self):
52         return '%s#%x' % (self.avm_class.name, id(self))
53
54
55 class _ScopeDict(dict):
56     def __init__(self, avm_class):
57         super(_ScopeDict, self).__init__()
58         self.avm_class = avm_class
59
60     def __repr__(self):
61         return '%s__Scope(%s)' % (
62             self.avm_class.name,
63             super(_ScopeDict, self).__repr__())
64
65
66 class _AVMClass(object):
67     def __init__(self, name_idx, name, static_properties=None):
68         self.name_idx = name_idx
69         self.name = name
70         self.method_names = {}
71         self.method_idxs = {}
72         self.methods = {}
73         self.method_pyfunctions = {}
74         self.static_properties = static_properties if static_properties else {}
75
76         self.variables = _ScopeDict(self)
77         self.constants = {}
78
79     def make_object(self):
80         return _AVMClass_Object(self)
81
82     def __repr__(self):
83         return '_AVMClass(%s)' % (self.name)
84
85     def register_methods(self, methods):
86         self.method_names.update(methods.items())
87         self.method_idxs.update(dict(
88             (idx, name)
89             for name, idx in methods.items()))
90
91
92 class _Multiname(object):
93     def __init__(self, kind):
94         self.kind = kind
95
96     def __repr__(self):
97         return '[MULTINAME kind: 0x%x]' % self.kind
98
99
100 def _read_int(reader):
101     res = 0
102     shift = 0
103     for _ in range(5):
104         buf = reader.read(1)
105         assert len(buf) == 1
106         b = compat_struct_unpack('<B', buf)[0]
107         res = res | ((b & 0x7f) << shift)
108         if b & 0x80 == 0:
109             break
110         shift += 7
111     return res
112
113
114 def _u30(reader):
115     res = _read_int(reader)
116     assert res & 0xf0000000 == 0
117     return res
118
119
120 _u32 = _read_int
121
122
123 def _s32(reader):
124     v = _read_int(reader)
125     if v & 0x80000000 != 0:
126         v = - ((v ^ 0xffffffff) + 1)
127     return v
128
129
130 def _s24(reader):
131     bs = reader.read(3)
132     assert len(bs) == 3
133     last_byte = b'\xff' if (ord(bs[2:3]) >= 0x80) else b'\x00'
134     return compat_struct_unpack('<i', bs + last_byte)[0]
135
136
137 def _read_string(reader):
138     slen = _u30(reader)
139     resb = reader.read(slen)
140     assert len(resb) == slen
141     return resb.decode('utf-8')
142
143
144 def _read_bytes(count, reader):
145     assert count >= 0
146     resb = reader.read(count)
147     assert len(resb) == count
148     return resb
149
150
151 def _read_byte(reader):
152     resb = _read_bytes(1, reader=reader)
153     res = compat_struct_unpack('<B', resb)[0]
154     return res
155
156
157 StringClass = _AVMClass('(no name idx)', 'String')
158 ByteArrayClass = _AVMClass('(no name idx)', 'ByteArray')
159 TimerClass = _AVMClass('(no name idx)', 'Timer')
160 TimerEventClass = _AVMClass('(no name idx)', 'TimerEvent', {'TIMER': 'timer'})
161 _builtin_classes = {
162     StringClass.name: StringClass,
163     ByteArrayClass.name: ByteArrayClass,
164     TimerClass.name: TimerClass,
165     TimerEventClass.name: TimerEventClass,
166 }
167
168
169 class _Undefined(object):
170     def __bool__(self):
171         return False
172     __nonzero__ = __bool__
173
174     def __hash__(self):
175         return 0
176
177     def __str__(self):
178         return 'undefined'
179     __repr__ = __str__
180
181
182 undefined = _Undefined()
183
184
185 class SWFInterpreter(object):
186     def __init__(self, file_contents):
187         self._patched_functions = {
188             (TimerClass, 'addEventListener'): lambda params: undefined,
189         }
190         code_tag = next(tag
191                         for tag_code, tag in _extract_tags(file_contents)
192                         if tag_code == 82)
193         p = code_tag.index(b'\0', 4) + 1
194         code_reader = io.BytesIO(code_tag[p:])
195
196         # Parse ABC (AVM2 ByteCode)
197
198         # Define a couple convenience methods
199         u30 = lambda *args: _u30(*args, reader=code_reader)
200         s32 = lambda *args: _s32(*args, reader=code_reader)
201         u32 = lambda *args: _u32(*args, reader=code_reader)
202         read_bytes = lambda *args: _read_bytes(*args, reader=code_reader)
203         read_byte = lambda *args: _read_byte(*args, reader=code_reader)
204
205         # minor_version + major_version
206         read_bytes(2 + 2)
207
208         # Constant pool
209         int_count = u30()
210         self.constant_ints = [0]
211         for _c in range(1, int_count):
212             self.constant_ints.append(s32())
213         self.constant_uints = [0]
214         uint_count = u30()
215         for _c in range(1, uint_count):
216             self.constant_uints.append(u32())
217         double_count = u30()
218         read_bytes(max(0, (double_count - 1)) * 8)
219         string_count = u30()
220         self.constant_strings = ['']
221         for _c in range(1, string_count):
222             s = _read_string(code_reader)
223             self.constant_strings.append(s)
224         namespace_count = u30()
225         for _c in range(1, namespace_count):
226             read_bytes(1)  # kind
227             u30()  # name
228         ns_set_count = u30()
229         for _c in range(1, ns_set_count):
230             count = u30()
231             for _c2 in range(count):
232                 u30()
233         multiname_count = u30()
234         MULTINAME_SIZES = {
235             0x07: 2,  # QName
236             0x0d: 2,  # QNameA
237             0x0f: 1,  # RTQName
238             0x10: 1,  # RTQNameA
239             0x11: 0,  # RTQNameL
240             0x12: 0,  # RTQNameLA
241             0x09: 2,  # Multiname
242             0x0e: 2,  # MultinameA
243             0x1b: 1,  # MultinameL
244             0x1c: 1,  # MultinameLA
245         }
246         self.multinames = ['']
247         for _c in range(1, multiname_count):
248             kind = u30()
249             assert kind in MULTINAME_SIZES, 'Invalid multiname kind %r' % kind
250             if kind == 0x07:
251                 u30()  # namespace_idx
252                 name_idx = u30()
253                 self.multinames.append(self.constant_strings[name_idx])
254             elif kind == 0x09:
255                 name_idx = u30()
256                 u30()
257                 self.multinames.append(self.constant_strings[name_idx])
258             else:
259                 self.multinames.append(_Multiname(kind))
260                 for _c2 in range(MULTINAME_SIZES[kind]):
261                     u30()
262
263         # Methods
264         method_count = u30()
265         MethodInfo = collections.namedtuple(
266             'MethodInfo',
267             ['NEED_ARGUMENTS', 'NEED_REST'])
268         method_infos = []
269         for method_id in range(method_count):
270             param_count = u30()
271             u30()  # return type
272             for _ in range(param_count):
273                 u30()  # param type
274             u30()  # name index (always 0 for youtube)
275             flags = read_byte()
276             if flags & 0x08 != 0:
277                 # Options present
278                 option_count = u30()
279                 for c in range(option_count):
280                     u30()  # val
281                     read_bytes(1)  # kind
282             if flags & 0x80 != 0:
283                 # Param names present
284                 for _ in range(param_count):
285                     u30()  # param name
286             mi = MethodInfo(flags & 0x01 != 0, flags & 0x04 != 0)
287             method_infos.append(mi)
288
289         # Metadata
290         metadata_count = u30()
291         for _c in range(metadata_count):
292             u30()  # name
293             item_count = u30()
294             for _c2 in range(item_count):
295                 u30()  # key
296                 u30()  # value
297
298         def parse_traits_info():
299             trait_name_idx = u30()
300             kind_full = read_byte()
301             kind = kind_full & 0x0f
302             attrs = kind_full >> 4
303             methods = {}
304             constants = None
305             if kind == 0x00:  # Slot
306                 u30()  # Slot id
307                 u30()  # type_name_idx
308                 vindex = u30()
309                 if vindex != 0:
310                     read_byte()  # vkind
311             elif kind == 0x06:  # Const
312                 u30()  # Slot id
313                 u30()  # type_name_idx
314                 vindex = u30()
315                 vkind = 'any'
316                 if vindex != 0:
317                     vkind = read_byte()
318                 if vkind == 0x03:  # Constant_Int
319                     value = self.constant_ints[vindex]
320                 elif vkind == 0x04:  # Constant_UInt
321                     value = self.constant_uints[vindex]
322                 else:
323                     return {}, None  # Ignore silently for now
324                 constants = {self.multinames[trait_name_idx]: value}
325             elif kind in (0x01, 0x02, 0x03):  # Method / Getter / Setter
326                 u30()  # disp_id
327                 method_idx = u30()
328                 methods[self.multinames[trait_name_idx]] = method_idx
329             elif kind == 0x04:  # Class
330                 u30()  # slot_id
331                 u30()  # classi
332             elif kind == 0x05:  # Function
333                 u30()  # slot_id
334                 function_idx = u30()
335                 methods[function_idx] = self.multinames[trait_name_idx]
336             else:
337                 raise ExtractorError('Unsupported trait kind %d' % kind)
338
339             if attrs & 0x4 != 0:  # Metadata present
340                 metadata_count = u30()
341                 for _c3 in range(metadata_count):
342                     u30()  # metadata index
343
344             return methods, constants
345
346         # Classes
347         class_count = u30()
348         classes = []
349         for class_id in range(class_count):
350             name_idx = u30()
351
352             cname = self.multinames[name_idx]
353             avm_class = _AVMClass(name_idx, cname)
354             classes.append(avm_class)
355
356             u30()  # super_name idx
357             flags = read_byte()
358             if flags & 0x08 != 0:  # Protected namespace is present
359                 u30()  # protected_ns_idx
360             intrf_count = u30()
361             for _c2 in range(intrf_count):
362                 u30()
363             u30()  # iinit
364             trait_count = u30()
365             for _c2 in range(trait_count):
366                 trait_methods, trait_constants = parse_traits_info()
367                 avm_class.register_methods(trait_methods)
368                 if trait_constants:
369                     avm_class.constants.update(trait_constants)
370
371         assert len(classes) == class_count
372         self._classes_by_name = dict((c.name, c) for c in classes)
373
374         for avm_class in classes:
375             avm_class.cinit_idx = u30()
376             trait_count = u30()
377             for _c2 in range(trait_count):
378                 trait_methods, trait_constants = parse_traits_info()
379                 avm_class.register_methods(trait_methods)
380                 if trait_constants:
381                     avm_class.constants.update(trait_constants)
382
383         # Scripts
384         script_count = u30()
385         for _c in range(script_count):
386             u30()  # init
387             trait_count = u30()
388             for _c2 in range(trait_count):
389                 parse_traits_info()
390
391         # Method bodies
392         method_body_count = u30()
393         Method = collections.namedtuple('Method', ['code', 'local_count'])
394         self._all_methods = []
395         for _c in range(method_body_count):
396             method_idx = u30()
397             u30()  # max_stack
398             local_count = u30()
399             u30()  # init_scope_depth
400             u30()  # max_scope_depth
401             code_length = u30()
402             code = read_bytes(code_length)
403             m = Method(code, local_count)
404             self._all_methods.append(m)
405             for avm_class in classes:
406                 if method_idx in avm_class.method_idxs:
407                     avm_class.methods[avm_class.method_idxs[method_idx]] = m
408             exception_count = u30()
409             for _c2 in range(exception_count):
410                 u30()  # from
411                 u30()  # to
412                 u30()  # target
413                 u30()  # exc_type
414                 u30()  # var_name
415             trait_count = u30()
416             for _c2 in range(trait_count):
417                 parse_traits_info()
418
419         assert p + code_reader.tell() == len(code_tag)
420
421     def patch_function(self, avm_class, func_name, f):
422         self._patched_functions[(avm_class, func_name)] = f
423
424     def extract_class(self, class_name, call_cinit=True):
425         try:
426             res = self._classes_by_name[class_name]
427         except KeyError:
428             raise ExtractorError('Class %r not found' % class_name)
429
430         if call_cinit and hasattr(res, 'cinit_idx'):
431             res.register_methods({'$cinit': res.cinit_idx})
432             res.methods['$cinit'] = self._all_methods[res.cinit_idx]
433             cinit = self.extract_function(res, '$cinit')
434             cinit([])
435
436         return res
437
438     def extract_function(self, avm_class, func_name):
439         p = self._patched_functions.get((avm_class, func_name))
440         if p:
441             return p
442         if func_name in avm_class.method_pyfunctions:
443             return avm_class.method_pyfunctions[func_name]
444         if func_name in self._classes_by_name:
445             return self._classes_by_name[func_name].make_object()
446         if func_name not in avm_class.methods:
447             raise ExtractorError('Cannot find function %s.%s' % (
448                 avm_class.name, func_name))
449         m = avm_class.methods[func_name]
450
451         def resfunc(args):
452             # Helper functions
453             coder = io.BytesIO(m.code)
454             s24 = lambda: _s24(coder)
455             u30 = lambda: _u30(coder)
456
457             registers = [avm_class.variables] + list(args) + [None] * m.local_count
458             stack = []
459             scopes = collections.deque([
460                 self._classes_by_name, avm_class.constants, avm_class.variables])
461             while True:
462                 opcode = _read_byte(coder)
463                 if opcode == 9:  # label
464                     pass  # Spec says: "Do nothing."
465                 elif opcode == 16:  # jump
466                     offset = s24()
467                     coder.seek(coder.tell() + offset)
468                 elif opcode == 17:  # iftrue
469                     offset = s24()
470                     value = stack.pop()
471                     if value:
472                         coder.seek(coder.tell() + offset)
473                 elif opcode == 18:  # iffalse
474                     offset = s24()
475                     value = stack.pop()
476                     if not value:
477                         coder.seek(coder.tell() + offset)
478                 elif opcode == 19:  # ifeq
479                     offset = s24()
480                     value2 = stack.pop()
481                     value1 = stack.pop()
482                     if value2 == value1:
483                         coder.seek(coder.tell() + offset)
484                 elif opcode == 20:  # ifne
485                     offset = s24()
486                     value2 = stack.pop()
487                     value1 = stack.pop()
488                     if value2 != value1:
489                         coder.seek(coder.tell() + offset)
490                 elif opcode == 21:  # iflt
491                     offset = s24()
492                     value2 = stack.pop()
493                     value1 = stack.pop()
494                     if value1 < value2:
495                         coder.seek(coder.tell() + offset)
496                 elif opcode == 32:  # pushnull
497                     stack.append(None)
498                 elif opcode == 33:  # pushundefined
499                     stack.append(undefined)
500                 elif opcode == 36:  # pushbyte
501                     v = _read_byte(coder)
502                     stack.append(v)
503                 elif opcode == 37:  # pushshort
504                     v = u30()
505                     stack.append(v)
506                 elif opcode == 38:  # pushtrue
507                     stack.append(True)
508                 elif opcode == 39:  # pushfalse
509                     stack.append(False)
510                 elif opcode == 40:  # pushnan
511                     stack.append(float('NaN'))
512                 elif opcode == 42:  # dup
513                     value = stack[-1]
514                     stack.append(value)
515                 elif opcode == 44:  # pushstring
516                     idx = u30()
517                     stack.append(self.constant_strings[idx])
518                 elif opcode == 48:  # pushscope
519                     new_scope = stack.pop()
520                     scopes.append(new_scope)
521                 elif opcode == 66:  # construct
522                     arg_count = u30()
523                     args = list(reversed(
524                         [stack.pop() for _ in range(arg_count)]))
525                     obj = stack.pop()
526                     res = obj.avm_class.make_object()
527                     stack.append(res)
528                 elif opcode == 70:  # callproperty
529                     index = u30()
530                     mname = self.multinames[index]
531                     arg_count = u30()
532                     args = list(reversed(
533                         [stack.pop() for _ in range(arg_count)]))
534                     obj = stack.pop()
535
536                     if obj == StringClass:
537                         if mname == 'String':
538                             assert len(args) == 1
539                             assert isinstance(args[0], (
540                                 int, compat_str, _Undefined))
541                             if args[0] == undefined:
542                                 res = 'undefined'
543                             else:
544                                 res = compat_str(args[0])
545                             stack.append(res)
546                             continue
547                         else:
548                             raise NotImplementedError(
549                                 'Function String.%s is not yet implemented'
550                                 % mname)
551                     elif isinstance(obj, _AVMClass_Object):
552                         func = self.extract_function(obj.avm_class, mname)
553                         res = func(args)
554                         stack.append(res)
555                         continue
556                     elif isinstance(obj, _AVMClass):
557                         func = self.extract_function(obj, mname)
558                         res = func(args)
559                         stack.append(res)
560                         continue
561                     elif isinstance(obj, _ScopeDict):
562                         if mname in obj.avm_class.method_names:
563                             func = self.extract_function(obj.avm_class, mname)
564                             res = func(args)
565                         else:
566                             res = obj[mname]
567                         stack.append(res)
568                         continue
569                     elif isinstance(obj, compat_str):
570                         if mname == 'split':
571                             assert len(args) == 1
572                             assert isinstance(args[0], compat_str)
573                             if args[0] == '':
574                                 res = list(obj)
575                             else:
576                                 res = obj.split(args[0])
577                             stack.append(res)
578                             continue
579                         elif mname == 'charCodeAt':
580                             assert len(args) <= 1
581                             idx = 0 if len(args) == 0 else args[0]
582                             assert isinstance(idx, int)
583                             res = ord(obj[idx])
584                             stack.append(res)
585                             continue
586                     elif isinstance(obj, list):
587                         if mname == 'slice':
588                             assert len(args) == 1
589                             assert isinstance(args[0], int)
590                             res = obj[args[0]:]
591                             stack.append(res)
592                             continue
593                         elif mname == 'join':
594                             assert len(args) == 1
595                             assert isinstance(args[0], compat_str)
596                             res = args[0].join(obj)
597                             stack.append(res)
598                             continue
599                     raise NotImplementedError(
600                         'Unsupported property %r on %r'
601                         % (mname, obj))
602                 elif opcode == 71:  # returnvoid
603                     res = undefined
604                     return res
605                 elif opcode == 72:  # returnvalue
606                     res = stack.pop()
607                     return res
608                 elif opcode == 73:  # constructsuper
609                     # Not yet implemented, just hope it works without it
610                     arg_count = u30()
611                     args = list(reversed(
612                         [stack.pop() for _ in range(arg_count)]))
613                     obj = stack.pop()
614                 elif opcode == 74:  # constructproperty
615                     index = u30()
616                     arg_count = u30()
617                     args = list(reversed(
618                         [stack.pop() for _ in range(arg_count)]))
619                     obj = stack.pop()
620
621                     mname = self.multinames[index]
622                     assert isinstance(obj, _AVMClass)
623
624                     # We do not actually call the constructor for now;
625                     # we just pretend it does nothing
626                     stack.append(obj.make_object())
627                 elif opcode == 79:  # callpropvoid
628                     index = u30()
629                     mname = self.multinames[index]
630                     arg_count = u30()
631                     args = list(reversed(
632                         [stack.pop() for _ in range(arg_count)]))
633                     obj = stack.pop()
634                     if isinstance(obj, _AVMClass_Object):
635                         func = self.extract_function(obj.avm_class, mname)
636                         res = func(args)
637                         assert res is undefined
638                         continue
639                     if isinstance(obj, _ScopeDict):
640                         assert mname in obj.avm_class.method_names
641                         func = self.extract_function(obj.avm_class, mname)
642                         res = func(args)
643                         assert res is undefined
644                         continue
645                     if mname == 'reverse':
646                         assert isinstance(obj, list)
647                         obj.reverse()
648                     else:
649                         raise NotImplementedError(
650                             'Unsupported (void) property %r on %r'
651                             % (mname, obj))
652                 elif opcode == 86:  # newarray
653                     arg_count = u30()
654                     arr = []
655                     for i in range(arg_count):
656                         arr.append(stack.pop())
657                     arr = arr[::-1]
658                     stack.append(arr)
659                 elif opcode == 93:  # findpropstrict
660                     index = u30()
661                     mname = self.multinames[index]
662                     for s in reversed(scopes):
663                         if mname in s:
664                             res = s
665                             break
666                     else:
667                         res = scopes[0]
668                     if mname not in res and mname in _builtin_classes:
669                         stack.append(_builtin_classes[mname])
670                     else:
671                         stack.append(res[mname])
672                 elif opcode == 94:  # findproperty
673                     index = u30()
674                     mname = self.multinames[index]
675                     for s in reversed(scopes):
676                         if mname in s:
677                             res = s
678                             break
679                     else:
680                         res = avm_class.variables
681                     stack.append(res)
682                 elif opcode == 96:  # getlex
683                     index = u30()
684                     mname = self.multinames[index]
685                     for s in reversed(scopes):
686                         if mname in s:
687                             scope = s
688                             break
689                     else:
690                         scope = avm_class.variables
691
692                     if mname in scope:
693                         res = scope[mname]
694                     elif mname in _builtin_classes:
695                         res = _builtin_classes[mname]
696                     else:
697                         # Assume uninitialized
698                         # TODO warn here
699                         res = undefined
700                     stack.append(res)
701                 elif opcode == 97:  # setproperty
702                     index = u30()
703                     value = stack.pop()
704                     idx = self.multinames[index]
705                     if isinstance(idx, _Multiname):
706                         idx = stack.pop()
707                     obj = stack.pop()
708                     obj[idx] = value
709                 elif opcode == 98:  # getlocal
710                     index = u30()
711                     stack.append(registers[index])
712                 elif opcode == 99:  # setlocal
713                     index = u30()
714                     value = stack.pop()
715                     registers[index] = value
716                 elif opcode == 102:  # getproperty
717                     index = u30()
718                     pname = self.multinames[index]
719                     if pname == 'length':
720                         obj = stack.pop()
721                         assert isinstance(obj, (compat_str, list))
722                         stack.append(len(obj))
723                     elif isinstance(pname, compat_str):  # Member access
724                         obj = stack.pop()
725                         if isinstance(obj, _AVMClass):
726                             res = obj.static_properties[pname]
727                             stack.append(res)
728                             continue
729
730                         assert isinstance(obj, (dict, _ScopeDict)),\
731                             'Accessing member %r on %r' % (pname, obj)
732                         res = obj.get(pname, undefined)
733                         stack.append(res)
734                     else:  # Assume attribute access
735                         idx = stack.pop()
736                         assert isinstance(idx, int)
737                         obj = stack.pop()
738                         assert isinstance(obj, list)
739                         stack.append(obj[idx])
740                 elif opcode == 104:  # initproperty
741                     index = u30()
742                     value = stack.pop()
743                     idx = self.multinames[index]
744                     if isinstance(idx, _Multiname):
745                         idx = stack.pop()
746                     obj = stack.pop()
747                     obj[idx] = value
748                 elif opcode == 115:  # convert_
749                     value = stack.pop()
750                     intvalue = int(value)
751                     stack.append(intvalue)
752                 elif opcode == 128:  # coerce
753                     u30()
754                 elif opcode == 130:  # coerce_a
755                     value = stack.pop()
756                     # um, yes, it's any value
757                     stack.append(value)
758                 elif opcode == 133:  # coerce_s
759                     assert isinstance(stack[-1], (type(None), compat_str))
760                 elif opcode == 147:  # decrement
761                     value = stack.pop()
762                     assert isinstance(value, int)
763                     stack.append(value - 1)
764                 elif opcode == 149:  # typeof
765                     value = stack.pop()
766                     return {
767                         _Undefined: 'undefined',
768                         compat_str: 'String',
769                         int: 'Number',
770                         float: 'Number',
771                     }[type(value)]
772                 elif opcode == 160:  # add
773                     value2 = stack.pop()
774                     value1 = stack.pop()
775                     res = value1 + value2
776                     stack.append(res)
777                 elif opcode == 161:  # subtract
778                     value2 = stack.pop()
779                     value1 = stack.pop()
780                     res = value1 - value2
781                     stack.append(res)
782                 elif opcode == 162:  # multiply
783                     value2 = stack.pop()
784                     value1 = stack.pop()
785                     res = value1 * value2
786                     stack.append(res)
787                 elif opcode == 164:  # modulo
788                     value2 = stack.pop()
789                     value1 = stack.pop()
790                     res = value1 % value2
791                     stack.append(res)
792                 elif opcode == 168:  # bitand
793                     value2 = stack.pop()
794                     value1 = stack.pop()
795                     assert isinstance(value1, int)
796                     assert isinstance(value2, int)
797                     res = value1 & value2
798                     stack.append(res)
799                 elif opcode == 171:  # equals
800                     value2 = stack.pop()
801                     value1 = stack.pop()
802                     result = value1 == value2
803                     stack.append(result)
804                 elif opcode == 175:  # greaterequals
805                     value2 = stack.pop()
806                     value1 = stack.pop()
807                     result = value1 >= value2
808                     stack.append(result)
809                 elif opcode == 192:  # increment_i
810                     value = stack.pop()
811                     assert isinstance(value, int)
812                     stack.append(value + 1)
813                 elif opcode == 208:  # getlocal_0
814                     stack.append(registers[0])
815                 elif opcode == 209:  # getlocal_1
816                     stack.append(registers[1])
817                 elif opcode == 210:  # getlocal_2
818                     stack.append(registers[2])
819                 elif opcode == 211:  # getlocal_3
820                     stack.append(registers[3])
821                 elif opcode == 212:  # setlocal_0
822                     registers[0] = stack.pop()
823                 elif opcode == 213:  # setlocal_1
824                     registers[1] = stack.pop()
825                 elif opcode == 214:  # setlocal_2
826                     registers[2] = stack.pop()
827                 elif opcode == 215:  # setlocal_3
828                     registers[3] = stack.pop()
829                 else:
830                     raise NotImplementedError(
831                         'Unsupported opcode %d' % opcode)
832
833         avm_class.method_pyfunctions[func_name] = resfunc
834         return resfunc