Allegro data file: Python parsing library

Allegro library for C (mostly used for game and multimedia apps programming) used its own container file format.

In general, it allows storage of arbitrary binary data blocks bundled together with some simple key-value style metadata ("properties") for every block. Allegro also pre-defines some simple formats for bitmaps, fonts, MIDI music, sound samples and palettes. Allegro library v4.0+ also support LZSS compression.

This spec applies to Allegro data files for library versions 2.2 up to 4.4.

Application

Allegro library (v2.2-v4.4)

KS implementation details

License: CC0-1.0

This page hosts a formal specification of Allegro data file using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.

Usage

Runtime 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 kaitaistruct

Code

Parse a local file and get structure in memory:

data = AllegroDat.from_file("path/to/local/file.Allegro data file")

Or parse structure from a bytes:

from kaitaistruct import KaitaiStream, BytesIO

raw = b"\x00\x01\x02..."
data = AllegroDat(KaitaiStream(BytesIO(raw)))

After that, one can get various attributes from the structure by invoking getter methods like:

data.pack_magic # => get pack magic

Python source code to parse Allegro data file

allegro_dat.py

# This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild

from pkg_resources import parse_version
import kaitaistruct
from kaitaistruct import KaitaiStruct, KaitaiStream, BytesIO
from enum import Enum


if parse_version(kaitaistruct.__version__) < parse_version('0.9'):
    raise Exception("Incompatible Kaitai Struct Python API: 0.9 or later is required, but you have %s" % (kaitaistruct.__version__))

class AllegroDat(KaitaiStruct):
    """Allegro library for C (mostly used for game and multimedia apps
    programming) used its own container file format.
    
    In general, it allows storage of arbitrary binary data blocks
    bundled together with some simple key-value style metadata
    ("properties") for every block. Allegro also pre-defines some simple
    formats for bitmaps, fonts, MIDI music, sound samples and
    palettes. Allegro library v4.0+ also support LZSS compression.
    
    This spec applies to Allegro data files for library versions 2.2 up
    to 4.4.
    
    .. seealso::
       Source - https://liballeg.org/stabledocs/en/datafile.html
    """

    class PackEnum(Enum):
        unpacked = 1936484398
    def __init__(self, _io, _parent=None, _root=None):
        self._io = _io
        self._parent = _parent
        self._root = _root if _root else self
        self._read()

    def _read(self):
        self.pack_magic = KaitaiStream.resolve_enum(AllegroDat.PackEnum, self._io.read_u4be())
        self.dat_magic = self._io.read_bytes(4)
        if not self.dat_magic == b"\x41\x4C\x4C\x2E":
            raise kaitaistruct.ValidationNotEqualError(b"\x41\x4C\x4C\x2E", self.dat_magic, self._io, u"/seq/1")
        self.num_objects = self._io.read_u4be()
        self.objects = [None] * (self.num_objects)
        for i in range(self.num_objects):
            self.objects[i] = AllegroDat.DatObject(self._io, self, self._root)


    class DatFont16(KaitaiStruct):
        """Simple monochrome monospaced font, 95 characters, 8x16 px
        characters.
        """
        def __init__(self, _io, _parent=None, _root=None):
            self._io = _io
            self._parent = _parent
            self._root = _root if _root else self
            self._read()

        def _read(self):
            self.chars = [None] * (95)
            for i in range(95):
                self.chars[i] = self._io.read_bytes(16)



    class DatBitmap(KaitaiStruct):
        def __init__(self, _io, _parent=None, _root=None):
            self._io = _io
            self._parent = _parent
            self._root = _root if _root else self
            self._read()

        def _read(self):
            self.bits_per_pixel = self._io.read_s2be()
            self.width = self._io.read_u2be()
            self.height = self._io.read_u2be()
            self.image = self._io.read_bytes_full()


    class DatFont(KaitaiStruct):
        def __init__(self, _io, _parent=None, _root=None):
            self._io = _io
            self._parent = _parent
            self._root = _root if _root else self
            self._read()

        def _read(self):
            self.font_size = self._io.read_s2be()
            _on = self.font_size
            if _on == 8:
                self.body = AllegroDat.DatFont8(self._io, self, self._root)
            elif _on == 16:
                self.body = AllegroDat.DatFont16(self._io, self, self._root)
            elif _on == 0:
                self.body = AllegroDat.DatFont39(self._io, self, self._root)


    class DatFont8(KaitaiStruct):
        """Simple monochrome monospaced font, 95 characters, 8x8 px
        characters.
        """
        def __init__(self, _io, _parent=None, _root=None):
            self._io = _io
            self._parent = _parent
            self._root = _root if _root else self
            self._read()

        def _read(self):
            self.chars = [None] * (95)
            for i in range(95):
                self.chars[i] = self._io.read_bytes(8)



    class DatObject(KaitaiStruct):
        def __init__(self, _io, _parent=None, _root=None):
            self._io = _io
            self._parent = _parent
            self._root = _root if _root else self
            self._read()

        def _read(self):
            self.properties = []
            i = 0
            while True:
                _ = AllegroDat.Property(self._io, self, self._root)
                self.properties.append(_)
                if not (_.is_valid):
                    break
                i += 1
            self.len_compressed = self._io.read_s4be()
            self.len_uncompressed = self._io.read_s4be()
            _on = self.type
            if _on == u"BMP ":
                self._raw_body = self._io.read_bytes(self.len_compressed)
                _io__raw_body = KaitaiStream(BytesIO(self._raw_body))
                self.body = AllegroDat.DatBitmap(_io__raw_body, self, self._root)
            elif _on == u"RLE ":
                self._raw_body = self._io.read_bytes(self.len_compressed)
                _io__raw_body = KaitaiStream(BytesIO(self._raw_body))
                self.body = AllegroDat.DatRleSprite(_io__raw_body, self, self._root)
            elif _on == u"FONT":
                self._raw_body = self._io.read_bytes(self.len_compressed)
                _io__raw_body = KaitaiStream(BytesIO(self._raw_body))
                self.body = AllegroDat.DatFont(_io__raw_body, self, self._root)
            else:
                self.body = self._io.read_bytes(self.len_compressed)

        @property
        def type(self):
            if hasattr(self, '_m_type'):
                return self._m_type if hasattr(self, '_m_type') else None

            self._m_type = self.properties[-1].magic
            return self._m_type if hasattr(self, '_m_type') else None


    class DatFont39(KaitaiStruct):
        """New bitmap font format introduced since Allegro 3.9: allows
        flexible designation of character ranges, 8-bit colored
        characters, etc.
        """
        def __init__(self, _io, _parent=None, _root=None):
            self._io = _io
            self._parent = _parent
            self._root = _root if _root else self
            self._read()

        def _read(self):
            self.num_ranges = self._io.read_s2be()
            self.ranges = [None] * (self.num_ranges)
            for i in range(self.num_ranges):
                self.ranges[i] = AllegroDat.DatFont39.Range(self._io, self, self._root)


        class Range(KaitaiStruct):
            def __init__(self, _io, _parent=None, _root=None):
                self._io = _io
                self._parent = _parent
                self._root = _root if _root else self
                self._read()

            def _read(self):
                self.mono = self._io.read_u1()
                self.start_char = self._io.read_u4be()
                self.end_char = self._io.read_u4be()
                self.chars = [None] * (((self.end_char - self.start_char) + 1))
                for i in range(((self.end_char - self.start_char) + 1)):
                    self.chars[i] = AllegroDat.DatFont39.FontChar(self._io, self, self._root)



        class FontChar(KaitaiStruct):
            def __init__(self, _io, _parent=None, _root=None):
                self._io = _io
                self._parent = _parent
                self._root = _root if _root else self
                self._read()

            def _read(self):
                self.width = self._io.read_u2be()
                self.height = self._io.read_u2be()
                self.body = self._io.read_bytes((self.width * self.height))



    class Property(KaitaiStruct):
        def __init__(self, _io, _parent=None, _root=None):
            self._io = _io
            self._parent = _parent
            self._root = _root if _root else self
            self._read()

        def _read(self):
            self.magic = (self._io.read_bytes(4)).decode(u"UTF-8")
            if self.is_valid:
                self.type = (self._io.read_bytes(4)).decode(u"UTF-8")

            if self.is_valid:
                self.len_body = self._io.read_u4be()

            if self.is_valid:
                self.body = (self._io.read_bytes(self.len_body)).decode(u"UTF-8")


        @property
        def is_valid(self):
            if hasattr(self, '_m_is_valid'):
                return self._m_is_valid if hasattr(self, '_m_is_valid') else None

            self._m_is_valid = self.magic == u"prop"
            return self._m_is_valid if hasattr(self, '_m_is_valid') else None


    class DatRleSprite(KaitaiStruct):
        def __init__(self, _io, _parent=None, _root=None):
            self._io = _io
            self._parent = _parent
            self._root = _root if _root else self
            self._read()

        def _read(self):
            self.bits_per_pixel = self._io.read_s2be()
            self.width = self._io.read_u2be()
            self.height = self._io.read_u2be()
            self.len_image = self._io.read_u4be()
            self.image = self._io.read_bytes_full()