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e5d; οΏ½ @ s d Z G ddοΏ½ dοΏ½ZdS )a Simple class to read IFF chunks.
An IFF chunk (used in formats such as AIFF, TIFF, RMFF (RealMedia File
Format)) has the following structure:
+----------------+
| ID (4 bytes) |
+----------------+
| size (4 bytes) |
+----------------+
| data |
| ... |
+----------------+
The ID is a 4-byte string which identifies the type of chunk.
The size field (a 32-bit value, encoded using big-endian byte order)
gives the size of the whole chunk, including the 8-byte header.
Usually an IFF-type file consists of one or more chunks. The proposed
usage of the Chunk class defined here is to instantiate an instance at
the start of each chunk and read from the instance until it reaches
the end, after which a new instance can be instantiated. At the end
of the file, creating a new instance will fail with an EOFError
exception.
Usage:
while True:
try:
chunk = Chunk(file)
except EOFError:
break
chunktype = chunk.getname()
while True:
data = chunk.read(nbytes)
if not data:
pass
# do something with data
The interface is file-like. The implemented methods are:
read, close, seek, tell, isatty.
Extra methods are: skip() (called by close, skips to the end of the chunk),
getname() (returns the name (ID) of the chunk)
The __init__ method has one required argument, a file-like object
(including a chunk instance), and one optional argument, a flag which
specifies whether or not chunks are aligned on 2-byte boundaries. The
default is 1, i.e. aligned.
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Z bigendianZ
inclheaderr ZstrflagοΏ½ r οΏ½ /usr/lib64/python3.8/chunk.pyοΏ½__init__4 s, zChunk.__init__c C s | j S )z*Return the name (ID) of the current chunk.)r
οΏ½r r r r οΏ½getnameN s z
Chunk.getnamec C s | j S )z%Return the size of the current chunk.)r r r r r οΏ½getsizeR s z
Chunk.getsizec C s | j s z | οΏ½οΏ½ W 5 d| _ X d S )NT)r οΏ½skipr r r r οΏ½closeV s z Chunk.closec C s | j rtdοΏ½οΏ½dS )NοΏ½ I/O operation on closed fileF)r οΏ½
ValueErrorr r r r οΏ½isatty] s z Chunk.isattyr c C sv | j rtdοΏ½οΏ½| js tdοΏ½οΏ½|dkr0|| j }n|dkrB|| j }|dk sT|| jkrXtοΏ½| jοΏ½| j | dοΏ½ || _dS )zοΏ½Seek to specified position into the chunk.
Default position is 0 (start of chunk).
If the file is not seekable, this will result in an error.
r! z cannot seekοΏ½ οΏ½ r N)
r r" r r r r οΏ½ RuntimeErrorr οΏ½seekr )r οΏ½posοΏ½whencer r r r' b s
z
Chunk.seekc C s | j rtdοΏ½οΏ½| jS )Nr! )r r" r r r r r r u s z
Chunk.tellοΏ½οΏ½οΏ½c C sοΏ½ | j rtdοΏ½οΏ½| j| jkr dS |dk r2| j| j }|| j| j krN| j| j }| jοΏ½|οΏ½}| jt|οΏ½ | _| j| jkrοΏ½| jrοΏ½| jd@ rοΏ½| jοΏ½dοΏ½}| jt|οΏ½ | _|S )zοΏ½Read at most size bytes from the chunk.
If size is omitted or negative, read until the end
of the chunk.
r! οΏ½ r r$ )r r" r r r r r r
)r οΏ½sizeοΏ½dataοΏ½dummyr r r r z s$ οΏ½οΏ½ z
Chunk.readc C sοΏ½ | j rtdοΏ½οΏ½| jrnzD| j| j }| jr:| jd@ r:|d }| jοΏ½|dοΏ½ | j| | _W dS tk
rl Y nX | j| jk rοΏ½t d| j| j οΏ½}| οΏ½
|οΏ½}|snt οΏ½qndS )zοΏ½Skip the rest of the chunk.
If you are not interested in the contents of the chunk,
this method should be called so that the file points to
the start of the next chunk.
r! r$ Ni ) r r" r r r r
r r' r οΏ½minr r )r οΏ½nr. r r r r οΏ½ s"
z
Chunk.skipN)TTF)r )r* ) οΏ½__name__οΏ½
__module__οΏ½ __qualname__r r r r r# r' r r r r r r r r 3 s
r N)οΏ½__doc__r r r r r οΏ½<module> s 2