284 lines
9.3 KiB
Python
284 lines
9.3 KiB
Python
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# This is a reference implementation of parsing, serializing, and deserializing ChocolateBird's struct definitions.
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# It is ported from the original GDscript to Python.
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import logging
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from io import TextIOWrapper
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from struct import pack_into, unpack_from, calcsize
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from collections.abc import Buffer
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class LeftoverBits:
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number_bits = 0
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bit_buffer = 0 # Stored as an integer
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class ReadBuffer:
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backing_buffer: Buffer
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position: int = 0
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def __init__(self, backing_buffer, position: int = 0) -> None:
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self.backing_buffer = backing_buffer
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self.position = position
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def get(self, format) -> tuple:
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values = unpack_from(format, self.backing_buffer, self.position)
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self.position += calcsize(format) # TODO: cache this
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return values
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class WriteBuffer:
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backing_buffer: Buffer
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position: int = 0
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def __init__(self, backing_buffer, position: int = 0) -> None:
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self.backing_buffer = backing_buffer
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self.position = position
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def put(self, format, *values) -> None:
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pack_into(format, self.backing_buffer, self.position, *values)
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self.position += calcsize(format) # TODO: cache this
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class StructType:
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name: str = None
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def __repr__(self) -> str:
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if self.name:
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return self.name
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return super().__repr__()
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def get_value(self, buffer: ReadBuffer, leftover_bits: LeftoverBits):
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raise NotImplementedError('Deserialization not implemented')
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def put_value(self, buffer: WriteBuffer, value, leftover_bits: LeftoverBits):
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raise NotImplementedError('Serialization not implemented')
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class SimpleStruct(StructType):
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format: str
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def __init__(self, format, name=None) -> None:
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self.format = format
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self.name = name
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def get_value(self, buffer: ReadBuffer, leftover_bits: LeftoverBits):
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return buffer.get(self.format)[0]
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def put_value(self, buffer: WriteBuffer, value, leftover_bits: LeftoverBits):
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buffer.put(self.format, value)
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class U24(StructType):
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name = 'u24'
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def get_value(self, buffer: ReadBuffer, leftover_bits: LeftoverBits):
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u16, u8 = buffer.get('<HB')
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return u16 | (u8 << 16)
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def put_value(self, buffer: WriteBuffer, value, leftover_bits: LeftoverBits):
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buffer.put('<HB', value & 0xFFFF, value >> 16)
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class S24(StructType):
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name = 's24'
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def get_value(self, buffer: ReadBuffer, leftover_bits: LeftoverBits):
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u16, u8 = buffer.get('<HB')
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unsigned = u16 | (u8 << 16)
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return unsigned - (2 * (unsigned & 0x800000))
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def put_value(self, buffer: WriteBuffer, value, leftover_bits: LeftoverBits):
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unsigned = value % 0x1000000
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buffer.put('<HB', unsigned & 0xFFFF, unsigned >> 16)
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class UBits(StructType):
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bits = 8
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def __init__(self, bits: int):
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self.bits = bits
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self.name = f'u{bits:d}'
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def get_value(self, buffer: ReadBuffer, leftover_bits: LeftoverBits):
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while leftover_bits.number_bits < self.bits:
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leftover_bits.bit_buffer |= buffer.get('<B')[0] << leftover_bits.number_bits
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leftover_bits.number_bits += 8
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value = leftover_bits.bit_buffer & ((1 << self.bits)-1)
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leftover_bits.bit_buffer = leftover_bits.bit_buffer >> self.bits
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leftover_bits.number_bits -= self.bits
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return value
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def put_value(self, buffer: WriteBuffer, value, leftover_bits: LeftoverBits):
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leftover_bits.bit_buffer |= value << leftover_bits.number_bits
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leftover_bits.number_bits += self.bits
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while leftover_bits.number_bits >= 8:
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buffer.put('<B', leftover_bits.bit_buffer & 0xFF)
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leftover_bits.number_bits -= 8
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leftover_bits.bit_buffer = leftover_bits.bit_buffer >> 8
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class Struct(StructType):
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members: list # Array of [name, StructType]
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def __init__(self, name=None) -> None:
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self.name = name
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self.members = []
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def get_value(self, buffer: ReadBuffer, leftover_bits: LeftoverBits):
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return {key: struct_type.get_value(buffer, leftover_bits) for key, struct_type in self.members}
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def put_value(self, buffer: WriteBuffer, value, leftover_bits: LeftoverBits):
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for key, struct_type in self.members:
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if not (key in value):
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logging.error(f'Key "{key}" missing from value supplied')
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return
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struct_type.put_value(buffer, value[key], leftover_bits)
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class StructArrayType(StructType):
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count: int
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struct_type: StructType
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def __init__(self, count, struct_type, name=None) -> None:
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self.count = count
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self.struct_type = struct_type
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self.name = name
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def get_value(self, buffer: ReadBuffer, leftover_bits: LeftoverBits) -> list:
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return [self.struct_type.get_value(buffer, leftover_bits) for i in range(self.count)]
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def put_value(self, buffer: WriteBuffer, value, leftover_bits: LeftoverBits) -> None:
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if len(value) < self.count:
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logging.error('Not enough values supplied')
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return
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for i in range(self.count):
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self.struct_type.put_value(buffer, value[i], leftover_bits)
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def get_base_structarraytypes() -> dict:
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return {
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'u8': SimpleStruct('<B', 'u8'),
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's8': SimpleStruct('<b', 's8'),
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'u16': SimpleStruct('<H', 'u16'),
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's16': SimpleStruct('<h', 's16'),
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'u24': U24(),
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's24': S24(),
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'u32': SimpleStruct('<I', 'u32'),
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's32': SimpleStruct('<i', 's32'),
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}
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def get_structarraytype(type: str, existing_structs: dict):
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tokens = type.split(' ')
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t: str = tokens[-1]
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inner_type: Struct = None
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if t in existing_structs:
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inner_type = existing_structs[t]
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elif t[0] == 'u':
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b: int = int(t[1:])
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if b > 0:
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inner_type = UBits(b)
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existing_structs[f'u{b:d}'] = inner_type # Cache it for future use
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if not inner_type:
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logging.error(f'typestring "{type}" has no matches for "{t}" in existing structs')
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return
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l: int = len(tokens)
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if l == 1:
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return inner_type
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# Our parsing goal is to turn 'a of b of c of d' into StructArrayType<StructArrayType<StructArrayType<d, c>, b>, a>
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# Our strategy is to parse backwards over the tokens, changing inner_type at each point
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# a of b of c of (d)
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# a of b of (c of d)
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# a of (b of c of d)
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# (a of b of c of d)
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# done
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i: int = l-2
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while i > -1:
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match tokens[i]:
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case 'of':
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i -= 1
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l1: int = int(tokens[i])
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if l1 > 1:
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inner_type = StructArrayType(l1, inner_type, name=type) # Might be worth caching these later on if we use them more
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i -= 1
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case k:
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logging.error(f'Invalid keyword used in type designator: "{k}"')
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return
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return inner_type
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def parse_struct_definitions_from_tsv_file(tsv_file: TextIOWrapper, existing_structs: dict) -> None:
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current_struct: Struct
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lines = tsv_file.read().rstrip().split('\n')
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for line in lines:
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# logging.debug(line)
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tokens = line.split('\t')
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size = len(tokens)
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if size < 2:
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continue
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# Size is at least 2
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type, label = tokens[:2]
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if type == 'struct':
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# New struct declaration
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current_struct = Struct(name=label)
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existing_structs[label] = current_struct
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elif type and label:
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current_struct.members.append([label, get_structarraytype(type, existing_structs)])
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# TODO: Maybe store the trailing comments somewhere?
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def parse_struct_definitions_from_tsv_filename(filename: str, existing_structs: dict) -> None:
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with open(filename, 'r') as file:
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parse_struct_definitions_from_tsv_file(file, existing_structs)
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def load_ff5_snes_struct_definitions() -> dict:
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existing_structs = get_base_structarraytypes()
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parse_struct_definitions_from_tsv_filename('structs_SNES_stubs.tsv', existing_structs)
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parse_struct_definitions_from_tsv_filename('5/structs/SNES_stubs.tsv', existing_structs)
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parse_struct_definitions_from_tsv_filename('5/structs/SNES.tsv', existing_structs)
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parse_struct_definitions_from_tsv_filename('5/structs/SNES_save.tsv', existing_structs)
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return existing_structs
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# Basic TSV dumper
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# This is mostly unrelated, but helpful for debugging.
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def flatten_keys(d: dict, prefix: str = '') -> dict:
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output = {}
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for k, v in d.items():
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if isinstance(v, dict):
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flat = flatten_keys(v, f'{prefix}{k}.')
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for k2, v2 in flat.items():
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output[k2] = v2
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else:
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output[f'{prefix}{k}'] = v
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return output
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def dump_tsv(filename, table):
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table_flat = [flatten_keys(d) for d in table]
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hex_digits = len(f'{len(table_flat)-1:X}') # See how long the hex representation of the last number will be, so we can zero-pad the rest to match.
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hex_format = f'0{hex_digits}X'
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with open(filename, 'w') as file:
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headers = list(table_flat[0].keys())
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file.write('\t'.join(['ID'] + headers) + '\n')
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for i, entry in enumerate(table_flat):
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file.write('\t'.join([f'0x{i:{hex_format}}'] + [str(entry[key]) for key in headers]) + '\n')
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# Example usage: run this script with a positional filename argument for a FF5 .sfc and it will load EnemyStats from it.
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if __name__ == '__main__':
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existing_structs = load_ff5_snes_struct_definitions()
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leftover_bits = LeftoverBits()
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from sys import argv
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if len(argv) > 1:
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rom_filename = argv[1]
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if rom_filename.endswith('.sfc'):
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with open(rom_filename, 'rb') as file:
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rom_data = file.read()
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buffer = ReadBuffer(rom_data, 0x100000)
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# enemy_stats = existing_structs['EnemyStats'].get_value(buffer, leftover_bits)
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enemy_stats = get_structarraytype('384 of EnemyStats', existing_structs).get_value(buffer, leftover_bits)
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print('Loaded EnemyStats table to enemy_stats! If you ran the python interpreter with -i flag, you can now examine it in the REPL.')
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# Also add a basic dumper
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if len(argv) > 2 and argv[2] == 'dump_tsv':
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dump_tsv('enemy_stats.tsv', enemy_stats)
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print('Dumped enemy_stats table to enemy_stats.tsv!')
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else:
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print(f'Argument "{rom_filename}" doesn\'t end in ".sfc", so it was not parsed as a FF5 SNES ROM.')
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else:
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print('Example usage: run this script with a positional filename argument for a FF5 .sfc and it will load EnemyStats from it.')
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