Bitstream

In order to implement the functionality that 010 editor has of treating the entire stream as a bitstream, a stream-wrapping class (pfp.bitwrap.BitwrappedStream) was made to allow a normal stream to tread like a limited bit stream.

This may be useful in other applications outside of pfp.

BitwrappedStream Reference Documentation

class pfp.bitwrap.BitwrappedStream(stream)

A stream that wraps other streams to provide bit-level access

close()

Close the stream

flush()

Flush the stream

is_eof()

Return if the stream has reached EOF or not without discarding any unflushed bits

Returns:True/False

isatty()

Return if the stream is a tty

read(num)

Read num number of bytes from the stream. Note that this will automatically resets/ends the current bit-reading if it does not end on an even byte AND self.padded is True. If self.padded is True, then the entire stream is treated as a bitstream.

Num:number of bytes to read Returns:the read bytes, or empty string if EOF has been reached

read_bits(num)

Read num number of bits from the stream

Num:number of bits to read Returns:a list of num bits, or an empty list if EOF has been reached

seek(pos, seek_type=0)

Seek to the specified position in the stream with seek_type. Unflushed bits will be discarded in the case of a seek.

The stream will also keep track of which bytes have and have not been consumed so that the dom will capture all of the bytes in the stream.

Pos:offset Seek_type:direction Returns:TODO

size()

Return the size of the stream, or -1 if it cannot be determined.

tell()

Return the current position in the stream (ignoring bit position)

Returns:int for the position in the stream

tell_bits()

Return the number of bits into the stream since the last whole byte.

Returns:int

unconsumed_ranges()

Return an IntervalTree of unconsumed ranges, of the format (start, end] with the end value not being included

write(data)

Write data to the stream

Data:the data to write to the stream Returns:None

write_bits(bits)

Write the bits to the stream.

Add the bits to the existing unflushed bits and write complete bytes to the stream.

exception pfp.bitwrap.EOFError

pfp.bitwrap.bits_to_bytes(bits)

Convert the bit list into bytes. (Assumes bits is a list whose length is a multiple of 8)

pfp.bitwrap.byte_to_bits(b)

Convert a byte into bits

pfp.bitwrap.bytes_to_bits(bytes_)

Convert bytes to a list of bits