Metadata-Version: 2.1
Name: cgrr
Version: 1.3.0
Summary: Classic Game Resource Reader simplifies parsing game resource files
Home-page: https://github.com/sopoforic/cgrr
Author: Tracy Poff
Author-email: tracy.poff@gmail.com
License: UNKNOWN
Description: # Classic Game Resource Reader
        
        cgrr holds utility functions used by other modules for parsing game
        resource files.
        
        ## Package contents
        
        At present, cgrr.py provides three things:
        
        1. `verify`, a simple function to verify that certain files exist in a path
        2. `File`, a namedtuple to be used with `verify`
        3. `FileReader`, a class used for reading files into dictionaries
        
        ### verify
        
        Pass this function a list of files (instances of the `File` namedtuple) and a
        path and it will verify that those files exist in that path. It is intended to
        be used to verify that a certain program resides in the given path, e.g. by
        checking that the program's main executable is in the expected place.
        
        ```python
        identifying_files = [
            File("ARCHERY.EXE", 31616,  "d8fae202edcc48d51a72026cbfbe7fa8"),
        ]
        path = "path/to/archery"
        verify(identifying_files, path)
        ```
        
        The call to `verify` above will return `True` iff a file
        `path/to/archery/ARCHERY.EXE` exists, is `31,616` bytes, and has md5 hash
        `d8fae202edcc48d51a72026cbfbe7fa8`. If `identifying_files` contains multiple
        `File` namedtuples, *all* of the files described in the list must be present.
        
        ### File
        
        `File` is simply a namedtuple representing a file. The fields of the namedtuple
        are `path`, `size`, and `md5`.
        
        To create a new `File`:
        
        ```python
        example = File("path/to/example.tle", 12345, "0123456789abcdef0123456789abcdef")
        ```
        
        The path should be given relative to some base path (e.g. the main path to the
        program to be identified by that file) which will be passed to `verify`
        separately.
        
        `size` is the file size in bytes.
        
        `md5` is the md5 hash of the file.
        
        ### FileReader
        
        FileReader is a factory that produces readers for specific file formats. A
        reader provides two methods, `pack` and `unpack`, used for parsing and
        unparsing data from files. Under the hood, it uses the `struct` module.
        
        Construct a file reader with `FileReader(format)`, where `format` is a
        string describing the file format, such as:
        
        ```python
        score_reader = FileReader("""
        <
        Uint32      score         # Score at index 0x00, before name
        string[16]  name
        options[6]  game_options  # A six byte field with a custom data format
        """)
        ```
        
        The format of each line is
        
            TYPE VARIABLE_NAME
        
        or
        
            TYPE[COUNT] VARIABLE_NAME
        
        If COUNT is not specified, it defaults to 1.
        
        Optionally, a line may contain a single character describing the
        endianness of the numbers in the file, in the style of struct. By
        default, little-endian ('<') integers are assumed.
        
        Characters following a pound sign ('#') are treated as comments and
        ignored.
        
        If TYPE is one of the builtin types supported by the struct module (e.g.
        Uint16), it will be processed by struct. For builtin types, COUNT is
        treated as the repeat count for struct: Uint32[4] means four 32-bit
        unsigned integers (16 bytes), and string[4] means a 4 byte string.
        
        Otherwise, TYPE is treated as a user-defined type. Then COUNT is the
        number of bytes occupied by the variable, and the FileReader will look
        for a function named parse_TYPE (e.g. parse_options) when unpacking the
        data. If found, the function will be called with the bytestring as an
        argument and the return value assigned as the value of the variable.
        Similarly, the FileReader will pass the variable to a function named
        unparse_TYPE (e.g. unparse_options) which should return a bytestring of
        length COUNT when packing the data. If those functions are not defined,
        the bytes will be returned as-is.
        
        The `Struct` used by this module can be accessed directly as
        `score_reader.struct`, if desired.
        
        The reader specified above will extract three variables from a 26-byte
        file: `score`, a (little-endian) 32-bit unsigned integer; `name`, a
        16-byte string; and `game_options`, a 6-byte field in a custom format.
        
        Given a file in the required format, the file can be parsed with:
        
        ```python
        data = scorefile.read(26)
        scores = score_reader.unpack(data)
        ```
        
        which will produce `scores`, a dictionary with three entries
        
        ```python
        scores = {"name" : "SomeName", "score" : 1234, "game_options" : b'......'}
        ```
        
        Given a dictionary with these entries, `pack` can be used to generate a
        scorefile in the original format.
        
        ```python
        data = score_reader.pack( {"name" : "Cheater",
                                   "score" : 9999,
                                   "game_options" : b'......'} )
        scorefile.write(data)
        ```
        
        Since we didn't define `parse_options` and `unparse_options` functions,
        the six bytes devoted to that variable are simply assigned directly. It
        might be more useful to parse the options, however:
        
        ```python
        def parse_options(b):
            return { 'option' + str(i) : b[i] for i in range(6) }
        
        def unparse_options(o):
            return bytes([o['option' + str(i)] for i in range(6)])
        ```
        
        #### FileReader.from_offsets
        
        If you know the offsets of data in a file, but not necessarily the format of the
        whole file, the `from_offsets` constructor may be more useful.
        
        Construct a file reader with `from_offsets(format_def)`, where `format_def` is a
        string describing the file format, such as:
        
        ```python
        FileReader.from_offsets('''
        <
        0x00 Uint32      score    # Score at index 0x00, before name
        0x04 string[16]  name
        0x14 options[6]  options  # A six byte field with a custom data format
        0x1a EOF
        ''')
        ```
        
        The format of each line is
        
            OFFSET TYPE VARIABLE_NAME
        
        or
        
            OFFSET TYPE[COUNT] VARIABLE_NAME
        
        The final line of format_def may be:
        
            FILE_LENGTH EOF
        
        OFFSET and FILE_LENGTH must be specified in hexadecimal. The number must
        begin with '0x' and may use either capital or lowercase, i.e. 0x1a and
        0x1A are equivalent.
        
        It is not required to specify offsets in any particular order.
        
        Optionally, a line may contain a single character describing the
        endianness of the numbers in the file, in the style of struct. By
        default, little-endian ('<') integers are assumed.
        
        For an explanation of the remaining segment of each line, see the
        documentation for `FileReader`.
        
        This function is useful if a file format contains unknown segments,
        because `from_offsets` will automatically fill in the unknown segments
        with dummy variables. So:
        
        ```python
        FileReader.from_offsets('''
        <
        0x00 Uint32      score    # Score at index 0x00, before name
        0x04 string[16]  name
        0x24 options[6]  options  # A six byte field with a custom data format
        0x50 EOF
        ''')
        ```
        
        is equivalent to:
        
        ```python
        FileReader('''
        <
        Uint32      score   # 0x00-0x03: Score at index 0x00, before name
        string[16]  name    # 0x04-0x13
        unknown[16] unk1    # 0x14-0x23
        options[6]  options # 0x24-0x29: A six byte field with a custom data format
        unknown[38] unk2    # 0x2a-0x4f
        ''')
        ```
        
        The EOF statement is not required, but if not specified, the variable
        with the highest offset specified will also be presumed to be the end of
        the file.
        
        ## Example usage
        
        cgrr.py is used by other modules in the CGRR project. For example:
        
        * [cgrr-gameboy](https://github.com/sopoforic/cgrr-gameboy), which reads
            and edits Game Boy ROM headers
        * [cgrr-gamecube](https://github.com/sopoforic/cgrr-gamecube), which reads
            and edits GameCube GCI files
        * [cgrr-mariospicross](https://github.com/sopoforic/cgrr-mariospicross),
            which reads and edits puzzles for the Game Boy game Mario's Picross
        * [cgrr-pokemon](https://github.com/sopoforic/cgrr-pokemon), which reads
            and edits save files for Pokemon games
        
        ## License
        
        CGRR is available under the GPL v3 or later. See the file COPYING for details.
        
Platform: UNKNOWN
Classifier: Development Status :: 4 - Beta
Classifier: Topic :: Software Development :: Libraries :: Python Modules
Description-Content-Type: text/markdown
