class Decompress(object):
STATE_MAGIC = 0
STATE_BLOCK_HEADER = 1
STATE_BLOCK = 2
def __init__(self):
self.__buff = lzo_buffer(MAX_BLOCK)
self.__fifo = Fifo()
self.__output = []
self.state = self.STATE_MAGIC
def __yield_output(self):
output = ''.join(self.__output)
self.__output = []
return output
def decompress(self, data):
self.__fifo.write(data)
while True:
# magic
if self.state == self.STATE_MAGIC:
magic = self.__fifo.readblock(len(LZO_MAGIC))
if not magic:
break
if magic != LZO_MAGIC:
raise Exception('Bad magic: %s' % magic)
self.state = self.STATE_BLOCK_HEADER
# block header
if self.state == self.STATE_BLOCK_HEADER:
header = self.__fifo.readblock(_BLOCK_HEADER_LENGTH)
if not header:
break
self.__block_length = unpack(_BLOCK_HEADER_FORMAT, header)[0]
self.__block_compressed = self.__block_length & 0x8000
self.__block_length ^= self.__block_compressed
if self.__block_length:
self.state = self.STATE_BLOCK
# block
if self.state == self.STATE_BLOCK:
block = self.__fifo.readblock(self.__block_length)
if not block:
break
if self.__block_compressed:
decomp = lzo1x_decompress(block, self.__buff)
self.__output.append(decomp)
else:
self.__output.append(block)
self.state = self.STATE_BLOCK_HEADER
return self.__yield_output()
