This page hosts a formal specification of .nes file format using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.
All parsing code for Python generated by Kaitai Struct depends on the Python runtime library. You have to install it before you can parse data.
The Python runtime library can be installed from PyPI:
python3 -m pip install kaitaistructParse a local file and get structure in memory:
data = Ines.from_file("path/to/local/file.nes")
Or parse structure from a bytes:
from kaitaistruct import KaitaiStream, BytesIO
raw = b"\x00\x01\x02..."
data = Ines(KaitaiStream(BytesIO(raw)))
After that, one can get various attributes from the structure by invoking getter methods like:
data.header # => get header
# This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild
# type: ignore
import kaitaistruct
from kaitaistruct import KaitaiStruct, KaitaiStream, BytesIO
from enum import IntEnum
if getattr(kaitaistruct, 'API_VERSION', (0, 9)) < (0, 11):
raise Exception("Incompatible Kaitai Struct Python API: 0.11 or later is required, but you have %s" % (kaitaistruct.__version__))
class Ines(KaitaiStruct):
"""
.. seealso::
Source - https://www.nesdev.org/wiki/INES
"""
def __init__(self, _io, _parent=None, _root=None):
super(Ines, self).__init__(_io)
self._parent = _parent
self._root = _root or self
self._read()
def _read(self):
self._raw_header = self._io.read_bytes(16)
_io__raw_header = KaitaiStream(BytesIO(self._raw_header))
self.header = Ines.Header(_io__raw_header, self, self._root)
if self.header.f6.trainer:
pass
self.trainer = self._io.read_bytes(512)
self.prg_rom = self._io.read_bytes(self.header.len_prg_rom * 16384)
self.chr_rom = self._io.read_bytes(self.header.len_chr_rom * 8192)
if self.header.f7.playchoice10:
pass
self.playchoice10 = Ines.Playchoice10(self._io, self, self._root)
if (not (self._io.is_eof())):
pass
self.title = (self._io.read_bytes_full()).decode(u"ASCII")
def _fetch_instances(self):
pass
self.header._fetch_instances()
if self.header.f6.trainer:
pass
if self.header.f7.playchoice10:
pass
self.playchoice10._fetch_instances()
if (not (self._io.is_eof())):
pass
class Header(KaitaiStruct):
def __init__(self, _io, _parent=None, _root=None):
super(Ines.Header, self).__init__(_io)
self._parent = _parent
self._root = _root
self._read()
def _read(self):
self.magic = self._io.read_bytes(4)
if not self.magic == b"\x4E\x45\x53\x1A":
raise kaitaistruct.ValidationNotEqualError(b"\x4E\x45\x53\x1A", self.magic, self._io, u"/types/header/seq/0")
self.len_prg_rom = self._io.read_u1()
self.len_chr_rom = self._io.read_u1()
self._raw_f6 = self._io.read_bytes(1)
_io__raw_f6 = KaitaiStream(BytesIO(self._raw_f6))
self.f6 = Ines.Header.F6(_io__raw_f6, self, self._root)
self._raw_f7 = self._io.read_bytes(1)
_io__raw_f7 = KaitaiStream(BytesIO(self._raw_f7))
self.f7 = Ines.Header.F7(_io__raw_f7, self, self._root)
self.len_prg_ram = self._io.read_u1()
self._raw_f9 = self._io.read_bytes(1)
_io__raw_f9 = KaitaiStream(BytesIO(self._raw_f9))
self.f9 = Ines.Header.F9(_io__raw_f9, self, self._root)
self._raw_f10 = self._io.read_bytes(1)
_io__raw_f10 = KaitaiStream(BytesIO(self._raw_f10))
self.f10 = Ines.Header.F10(_io__raw_f10, self, self._root)
self.reserved = self._io.read_bytes(5)
if not self.reserved == b"\x00\x00\x00\x00\x00":
raise kaitaistruct.ValidationNotEqualError(b"\x00\x00\x00\x00\x00", self.reserved, self._io, u"/types/header/seq/8")
def _fetch_instances(self):
pass
self.f6._fetch_instances()
self.f7._fetch_instances()
self.f9._fetch_instances()
self.f10._fetch_instances()
class F10(KaitaiStruct):
"""
.. seealso::
Source - https://www.nesdev.org/wiki/INES#Flags_10
"""
class TvSystem(IntEnum):
ntsc = 0
dual1 = 1
pal = 2
dual2 = 3
def __init__(self, _io, _parent=None, _root=None):
super(Ines.Header.F10, self).__init__(_io)
self._parent = _parent
self._root = _root
self._read()
def _read(self):
self.reserved1 = self._io.read_bits_int_be(2)
self.bus_conflict = self._io.read_bits_int_be(1) != 0
self.prg_ram = self._io.read_bits_int_be(1) != 0
self.reserved2 = self._io.read_bits_int_be(2)
self.tv_system = KaitaiStream.resolve_enum(Ines.Header.F10.TvSystem, self._io.read_bits_int_be(2))
def _fetch_instances(self):
pass
class F6(KaitaiStruct):
"""
.. seealso::
Source - https://www.nesdev.org/wiki/INES#Flags_6
"""
class Mirroring(IntEnum):
horizontal = 0
vertical = 1
def __init__(self, _io, _parent=None, _root=None):
super(Ines.Header.F6, self).__init__(_io)
self._parent = _parent
self._root = _root
self._read()
def _read(self):
self.lower_mapper = self._io.read_bits_int_be(4)
self.four_screen = self._io.read_bits_int_be(1) != 0
self.trainer = self._io.read_bits_int_be(1) != 0
self.has_battery_ram = self._io.read_bits_int_be(1) != 0
self.mirroring = KaitaiStream.resolve_enum(Ines.Header.F6.Mirroring, self._io.read_bits_int_be(1))
def _fetch_instances(self):
pass
class F7(KaitaiStruct):
"""
.. seealso::
Source - https://www.nesdev.org/wiki/INES#Flags_7
"""
def __init__(self, _io, _parent=None, _root=None):
super(Ines.Header.F7, self).__init__(_io)
self._parent = _parent
self._root = _root
self._read()
def _read(self):
self.upper_mapper = self._io.read_bits_int_be(4)
self.format = self._io.read_bits_int_be(2)
self.playchoice10 = self._io.read_bits_int_be(1) != 0
self.vs_unisystem = self._io.read_bits_int_be(1) != 0
def _fetch_instances(self):
pass
class F9(KaitaiStruct):
"""
.. seealso::
Source - https://www.nesdev.org/wiki/INES#Flags_9
"""
class TvSystem(IntEnum):
ntsc = 0
pal = 1
def __init__(self, _io, _parent=None, _root=None):
super(Ines.Header.F9, self).__init__(_io)
self._parent = _parent
self._root = _root
self._read()
def _read(self):
self.reserved = self._io.read_bits_int_be(7)
self.tv_system = KaitaiStream.resolve_enum(Ines.Header.F9.TvSystem, self._io.read_bits_int_be(1))
def _fetch_instances(self):
pass
@property
def mapper(self):
"""
.. seealso::
Source - https://www.nesdev.org/wiki/Mapper
"""
if hasattr(self, '_m_mapper'):
return self._m_mapper
self._m_mapper = self.f6.lower_mapper | self.f7.upper_mapper << 4
return getattr(self, '_m_mapper', None)
class Playchoice10(KaitaiStruct):
"""
.. seealso::
Source - https://www.nesdev.org/wiki/PC10_ROM-Images
"""
def __init__(self, _io, _parent=None, _root=None):
super(Ines.Playchoice10, self).__init__(_io)
self._parent = _parent
self._root = _root
self._read()
def _read(self):
self.inst_rom = self._io.read_bytes(8192)
self.prom = Ines.Playchoice10.Prom(self._io, self, self._root)
def _fetch_instances(self):
pass
self.prom._fetch_instances()
class Prom(KaitaiStruct):
def __init__(self, _io, _parent=None, _root=None):
super(Ines.Playchoice10.Prom, self).__init__(_io)
self._parent = _parent
self._root = _root
self._read()
def _read(self):
self.data = self._io.read_bytes(16)
self.counter_out = self._io.read_bytes(16)
def _fetch_instances(self):
pass