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Tie up loose ends by adding TODOs and documentation for a few remaining bits in decompiler.

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This commit is contained in:
Jennifer Taylor 2021-05-11 17:01:35 +00:00
parent b184ae3169
commit 26c2a99a6e
2 changed files with 166 additions and 47 deletions
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204
bemani/format/afp/decompile.py
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@ -288,6 +288,15 @@ class ExpressionStatement(Statement):
return [f"{prefix}{self.expr.render(prefix, verbose=verbose)};"]
class StopSoundStatement(Statement):
# Stop all sounds, this is an actionscript-specific opcode.
def __repr__(self) -> str:
return "builtin_StopAllSounds()"
def render(self, prefix: str, verbose: bool = False) -> List[str]:
return [f"{prefix}builtin_StopAllSounds();"]
class StopMovieStatement(Statement):
# Stop the movie, this is an actionscript-specific opcode.
def __repr__(self) -> str:
@ -499,6 +508,12 @@ class GetTimeFunctionCall(FunctionCall):
super().__init__("builtin_GetCurrentPlaybackPosition", [])
class GetPathFunctionCall(FunctionCall):
# Call the built-in 'get time' method which returns the current playback position.
def __init__(self, movieclip: Any) -> None:
super().__init__("builtin_GetPathOfMovie", [movieclip])
class MethodCall(Expression):
# Call a method on an object.
def __init__(self, objectref: Any, name: Union[str, int, Expression], params: List[Any]) -> None:
@ -2211,6 +2226,9 @@ class ByteCodeDecompiler(VerboseOutput):
# exist before combining them, and we can't do that until we walk the stack, and the
# stack walking algorithm both a) comes later and b) relies on all ifs being processed.
# So, this stays as a beta for now, and will possibly be integrated at a later time.
# If we want to use this, we should probably reformat it to work on the finished
# statement list we get after fully rendering the stack, and use it in the optimization
# pass phase to rewrite code with fewer (possibly sometimes no) gotos.
chunks_by_id: Dict[int, ArbitraryCodeChunk] = {chunk.id: chunk for chunk in chunks}
chunks_examined: Set[int] = set()
@ -2540,6 +2558,10 @@ class ByteCodeDecompiler(VerboseOutput):
chunk.actions[i] = PreviousFrameStatement()
continue
if action.opcode == AP2Action.STOP_SOUND:
chunk.actions[i] = StopSoundStatement()
continue
if action.opcode == AP2Action.CLONE_SPRITE:
depth = stack.pop()
if not isinstance(depth, (int, Expression)):
@ -2556,35 +2578,6 @@ class ByteCodeDecompiler(VerboseOutput):
chunk.actions[i] = RemoveSpriteStatement(obj)
continue
if action.opcode == AP2Action.GET_VARIABLE:
variable_name = stack.pop()
if isinstance(variable_name, (str, StringConstant)):
stack.append(Variable(variable_name))
else:
# This is probably a reference to a variable by
# string concatenation.
stack.append(Member(GLOBAL, variable_name))
chunk.actions[i] = NopStatement()
continue
if action.opcode == AP2Action.DELETE:
member_name = stack.pop()
if not isinstance(member_name, (str, int, Expression)):
raise Exception("Logic error!")
obj_name = stack.pop()
chunk.actions[i] = DeleteMemberStatement(obj_name, member_name)
continue
if action.opcode == AP2Action.DELETE2:
variable_name = stack.pop()
if not isinstance(variable_name, (str, StringConstant)):
raise Exception("Logic error!")
chunk.actions[i] = DeleteVariableStatement(variable_name)
continue
if action.opcode == AP2Action.TO_NUMBER:
obj_ref = stack.pop()
stack.append(FunctionCall('int', [obj_ref]))
@ -2687,6 +2680,18 @@ class ByteCodeDecompiler(VerboseOutput):
chunk.actions[i] = NopStatement()
continue
if action.opcode == AP2Action.GET_VARIABLE:
variable_name = stack.pop()
if isinstance(variable_name, (str, StringConstant)):
stack.append(Variable(variable_name))
else:
# This is probably a reference to a variable by
# string concatenation.
stack.append(Member(GLOBAL, variable_name))
chunk.actions[i] = NopStatement()
continue
if action.opcode == AP2Action.SET_VARIABLE:
set_value = stack.pop()
local_name = stack.pop()
@ -2699,6 +2704,33 @@ class ByteCodeDecompiler(VerboseOutput):
continue
if action.opcode == AP2Action.DELETE:
member_name = stack.pop()
if not isinstance(member_name, (str, int, Expression)):
raise Exception("Logic error!")
obj_name = stack.pop()
chunk.actions[i] = DeleteMemberStatement(obj_name, member_name)
continue
if action.opcode == AP2Action.DELETE2:
variable_name = stack.pop()
if not isinstance(variable_name, (str, StringConstant)):
raise Exception("Logic error!")
chunk.actions[i] = DeleteVariableStatement(variable_name)
continue
if action.opcode == AP2Action.GET_MEMBER:
member_name = stack.pop()
if not isinstance(member_name, (str, int, Expression)):
raise Exception("Logic error!")
object_reference = stack.pop()
stack.append(Member(object_reference, member_name))
chunk.actions[i] = NopStatement()
continue
if action.opcode == AP2Action.SET_MEMBER:
set_value = stack.pop()
member_name = stack.pop()
@ -2709,6 +2741,30 @@ class ByteCodeDecompiler(VerboseOutput):
chunk.actions[i] = SetMemberStatement(object_reference, member_name, set_value)
continue
if action.opcode == AP2Action.GET_PROPERTY:
property_int = stack.pop()
if not isinstance(property_int, int):
# Its possible that code which uses this outdated SWF GET_PROPERTY call
# might dynamically calculate the integer which it wants to use to get
# a property on. But, probably not. I haven't seen any code use this or
# SET_PROPERTY so this is just here for documentation.
raise Exception("Logic error!")
object_reference = stack.pop()
stack.append(Member(object_reference, StringConstant(property_int + 0x100)))
chunk.actions[i] = NopStatement()
continue
if action.opcode == AP2Action.SET_PROPERTY:
set_value = stack.pop()
property_int = stack.pop()
if not isinstance(property_int, int):
raise Exception("Logic error!")
object_reference = stack.pop()
chunk.actions[i] = SetMemberStatement(object_reference, StringConstant(property_int + 0x100), set_value)
continue
if action.opcode == AP2Action.DEFINE_LOCAL:
set_value = stack.pop()
local_name = stack.pop()
@ -2723,20 +2779,9 @@ class ByteCodeDecompiler(VerboseOutput):
if not isinstance(local_name, (str, StringConstant)):
raise Exception(f"Logic error, local name {local_name} is not a string!")
# TODO: Should this be NULL?
chunk.actions[i] = SetLocalStatement(local_name, UNDEFINED)
continue
if action.opcode == AP2Action.GET_MEMBER:
member_name = stack.pop()
if not isinstance(member_name, (str, int, Expression)):
raise Exception("Logic error!")
object_reference = stack.pop()
stack.append(Member(object_reference, member_name))
chunk.actions[i] = NopStatement()
continue
if action.opcode == AP2Action.NEW_OBJECT:
object_name = stack.pop()
if not isinstance(object_name, (str, StringConstant)):
@ -2896,8 +2941,6 @@ class ByteCodeDecompiler(VerboseOutput):
continue
if action.opcode == AP2Action.PUSH_DUPLICATE:
# TODO: This might benefit from generating a temp variable assignment
# and pushing that onto the stack twice, instead of whatever's on the stack.
dup = stack.pop()
stack.append(dup)
stack.append(dup)
@ -2910,6 +2953,57 @@ class ByteCodeDecompiler(VerboseOutput):
chunk.actions[i] = NopStatement()
continue
if action.opcode == AP2Action.TARGET_PATH:
clip = stack.pop()
stack.append(GetPathFunctionCall(clip))
chunk.actions[i] = NopStatement()
continue
if action.opcode == AP2Action.CAST_OP:
obj_ref = stack.pop()
class_ref = stack.pop()
stack.append(FunctionCall('cast', [obj_ref, class_ref]))
chunk.actions[i] = NopStatement()
continue
if action.opcode == AP2Action.IMPLEMENTS_OP:
# This appears to be completely unimplemented/broken in
# Bishi so I have no idea what it intends to do. Probably
# I could look at the SWF spec and infer the functionality
# but there aren't any files that I've found in any games
# that use this opcode, so meh.
raise Exception(f"TODO: {action}")
if action.opcode == AP2Action.STACK_SWAP:
first = stack.pop()
second = stack.pop()
stack.append(first)
stack.append(second)
chunk.actions[i] = NopStatement()
continue
# None of the below actions are understood outside of the fact
# that they operate entirely on the stack. They do not appear to
# be used in any game code I've come across and might be remnants
# of when the code was for playing SWF directly.
if action.opcode == AP2Action.ENUMERATE2:
raise Exception(f"TODO: {action}")
if action.opcode == AP2Action.EXTENDS:
raise Exception(f"TODO: {action}")
if action.opcode == AP2Action.END_DRAG:
raise Exception(f"TODO: {action}")
if action.opcode == AP2Action.NEW_METHOD:
raise Exception(f"TODO: {action}")
if action.opcode == AP2Action.GET_TARGET:
raise Exception(f"TODO: {action}")
if isinstance(action, NullReturnStatement):
# We already handled this
continue
@ -2939,8 +3033,7 @@ class ByteCodeDecompiler(VerboseOutput):
)
continue
self.vprint(stack)
raise Exception(f"TODO: {action}")
raise Exception(f"Unexpected action {action}, the cases above should be exhaustive!")
# Now, clean up code generation.
new_actions: List[ConvertedAction] = []
@ -3983,6 +4076,29 @@ class ByteCodeDecompiler(VerboseOutput):
if not any_changed:
break
# TODO: There's definitely a lot missing from this decompilation process.
# For one, function definitions do not include any mention of number of
# arguments. It appears that functions take arguments in the registers
# and when you call a function/method, the values that are popped from
# the stack for the function/method call are placed into registers for the
# function itself to access. However, there's some implicit parameters such
# as "_this" which is even checked for in some Bishi code. Ideally the code
# can be cross-referenced with function calls to determine the number of
# arguments and the decompilation can be improved in that regard, but we
# would need to nail down function call semantics better. The TRACE opcode
# is still active in Bishi and its output can be coaxed to appear in stdout
# so it would be possible to craft some bytecode and print out the register
# contents in a function call to nail this down, but it is left as a future
# enhancement.
# TODO: If statements still don't support compound or properly, and resort
# to using nasty gotos. We have a prototype of an algorithm above with its
# own TODO section that can possibly fix this, but I haven't taken the time
# to try to fix it up and integrate it. It would produde far more readable
# code in some instances. We also would probably want to collapse some really
# long if chains to swithc statements or if/elif/else blocks for readability
# but that is also left as a future enhancement.
# Let's sanity check the code for a few things that might trip us up.
self.__verify_balanced_labels(statements)
self.__verify_no_empty_ifs(statements)

9
bemani/format/afp/types/ap2.py
View File

@ -210,10 +210,11 @@ class AP2Action:
# variable with that name equal to the first object.
SET_VARIABLE = 15
# Similar to get variable.
# Similar to GET_MEMBER, but the member value is an integer in the range 0x0-0x15 which
# gets added to 0x100 and looked up in StringConstants.
GET_PROPERTY = 16
# Simiar to set variable.
# Similar to SET_MEMBER in exactly the same way GET_PROPERTY is similar to GET_MEMBER.
SET_PROPERTY = 17
# Clone a sprite that's specified on the stack.
@ -656,7 +657,9 @@ class Register(Expression):
class StringConstant(Expression):
__PROPERTIES: List[Tuple[int, str]] = [
# Seems to be properties on every object.
# Seems to be properties on every object. These also match the original
# SWF properties up to 0x115. GET_PROPERTY and SET_PROPERTY use these
# values to determine what to look up on an object.
(0x100, '_x'),
(0x101, '_y'),
(0x102, '_xscale'),