ConstByteStore Class Reference

Inheritance diagram for ConstByteStore:

Public Member Functions
def	__init__ (self, data, bitlength=None, offset=None)
def	getbit (self, pos)
def	getbyte (self, pos)
def	getbyteslice (self, start, end)
def	bytelength (self)
def	__copy__ (self)
def	byteoffset (self)
def	rawbytes (self)

Public Attributes
	offset
	bitlength

Protected Member Functions
def	_appendstore (self, store)
def	_prependstore (self, store)

Protected Attributes
	_rawarray

Static Private Attributes
tuple	__slots__ = ('offset', '_rawarray', 'bitlength')

Detailed Description

Stores raw bytes together with a bit offset and length.

Used internally - not part of public interface.

Definition at line 132 of file bitstring.py.

Constructor & Destructor Documentation

__init__()

def __init__	(		self,
			data,
			bitlength = None,
			offset = None
	)

data is either a bytearray or a MmapByteArray

Definition at line 140 of file bitstring.py.

    def __init__(self, data, bitlength=None, offset=None):
        """data is either a bytearray or a MmapByteArray"""
        self._rawarray = data
        if offset is None:
            offset = 0
        if bitlength is None:
            bitlength = 8 * len(data) - offset
        self.offset = offset
        self.bitlength = bitlength
 

Member Function Documentation

__copy__()

def __copy__

(

self

)

Definition at line 172 of file bitstring.py.

    def __copy__(self):
        return ByteStore(self._rawarray[:], self.bitlength, self.offset)
 

_appendstore()

def _appendstore (   self,   store  )

protected

Join another store on to the end of this one.

Definition at line 175 of file bitstring.py.

    def _appendstore(self, store):
        """Join another store on to the end of this one."""
        if not store.bitlength:
            return
        # Set new array offset to the number of bits in the final byte of current array.
        store = offsetcopy(store, (self.offset + self.bitlength) % 8)
        if store.offset:
            # first do the byte with the join.
            joinval = (self._rawarray.pop() & (255 ^ (255 >> store.offset)) |
                       (store.getbyte(0) & (255 >> store.offset)))
            self._rawarray.append(joinval)
            self._rawarray.extend(store._rawarray[1:])
        else:
            self._rawarray.extend(store._rawarray)
        self.bitlength += store.bitlength
 

_prependstore()

def _prependstore (   self,   store  )

protected

Join another store on to the start of this one.

Definition at line 191 of file bitstring.py.

    def _prependstore(self, store):
        """Join another store on to the start of this one."""
        if not store.bitlength:
            return
            # Set the offset of copy of store so that it's final byte
        # ends in a position that matches the offset of self,
        # then join self on to the end of it.
        store = offsetcopy(store, (self.offset - store.bitlength) % 8)
        assert (store.offset + store.bitlength) % 8 == self.offset % 8
        bit_offset = self.offset % 8
        if bit_offset:
            # first do the byte with the join.
            store.setbyte(-1, (store.getbyte(-1) & (255 ^ (255 >> bit_offset)) |
                               (self._rawarray[self.byteoffset] & (255 >> bit_offset))))
            store._rawarray.extend(self._rawarray[self.byteoffset + 1: self.byteoffset + self.bytelength])
        else:
            store._rawarray.extend(self._rawarray[self.byteoffset: self.byteoffset + self.bytelength])
        self._rawarray = store._rawarray
        self.offset = store.offset
        self.bitlength += store.bitlength
 

bytelength()

def bytelength

(

self

)

Definition at line 165 of file bitstring.py.

    def bytelength(self):
        if not self.bitlength:
            return 0
        sb = self.offset // 8
        eb = (self.offset + self.bitlength - 1) // 8
        return eb - sb + 1
 

byteoffset()

def byteoffset

(

self

)

Definition at line 213 of file bitstring.py.

    def byteoffset(self):
        return self.offset // 8
 

getbit()

def getbit	(		self,
			pos
	)

Definition at line 150 of file bitstring.py.

    def getbit(self, pos):
        assert 0 <= pos < self.bitlength
        byte, bit = divmod(self.offset + pos, 8)
        return bool(self._rawarray[byte] & (128 >> bit))
 

getbyte()

def getbyte	(		self,
			pos
	)

Direct access to byte data.

Definition at line 155 of file bitstring.py.

    def getbyte(self, pos):
        """Direct access to byte data."""
        return self._rawarray[pos]
 

getbyteslice()

def getbyteslice	(		self,
			start,
			end
	)

Direct access to byte data.

Definition at line 159 of file bitstring.py.

    def getbyteslice(self, start, end):
        """Direct access to byte data."""
        c = self._rawarray[start:end]
        return c
 

rawbytes()

def rawbytes

(

self

)

Definition at line 217 of file bitstring.py.

    def rawbytes(self):
        return self._rawarray
 
 

Member Data Documentation

__slots__

tuple __slots__ = ('offset', '_rawarray', 'bitlength')

staticprivate

Definition at line 138 of file bitstring.py.

_rawarray

_rawarray

protected

Definition at line 142 of file bitstring.py.

bitlength

bitlength

Definition at line 148 of file bitstring.py.

offset

offset

Definition at line 147 of file bitstring.py.

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The documentation for this class was generated from the following file:

• trg/scripts/bitstring.py