def decompress(data: bytes) -> bytes:
rdr = BinaryReader(data)
wtr = BinaryWriter()
compression_type = rdr.read_uint8()
if compression_type == 0x24:
blocksize = 4
elif compression_type == 0x28:
blocksize = 8
else:
raise Exception(
"Tried to decompress something as huffman that isn't huffman")
ds = rdr.read_uint24()
if ds == 0:
rdr.read_uint32()
# Read the tree
treesize = (rdr.read_uint8() + 1) * 2
tree_end = (rdr.c - 1) + treesize
rootNode = HuffTreeNode.from_rdr(rdr, False, 5, tree_end)
rdr.c = tree_end
# Decompress with the tree
bitsleft = 0 # amount of bits left to read from {commands}
current_size = 0
currentNode = rootNode
cashedbyte = -1
while current_size < ds:
# Find next refrence to commands node
while not currentNode.is_data:
if bitsleft == 0:
data = rdr.read_uint32()
bitsleft = 32
bitsleft -= 1
nextIsOne = (data & (1 << bitsleft)) != 0
if nextIsOne:
currentNode = currentNode.child1
else:
currentNode = currentNode.child0
if blocksize == 8:
current_size += 1
wtr.write_uint8(currentNode.data)
elif blocksize == 4:
if cashedbyte < 0:
cashedbyte = currentNode.data
else:
cashedbyte |= currentNode.data << 4
wtr.write_uint8(cashedbyte)
current_size += 1
cashedbyte = -1
currentNode = rootNode
return wtr.data
def from_rdr(cls,
rdr: BinaryReader,
is_data: bool,
relative_offset,
max_stream_pos,
parent=None):
self = cls(is_data, parent=parent)
if rdr.c >= max_stream_pos:
return
self.data = rdr.read_uint8()
if not is_data:
offset = self.data & 0x3F
zeroIsData = (self.data & 0x80) > 0
oneIsData = (self.data & 0x40) > 0
# off AND NOT == off XOR (off AND 1)
zeroRelOffset = (relative_offset ^
(relative_offset & 1)) + offset * 2 + 2
currStreamPos = rdr.c
rdr.c += (zeroRelOffset - relative_offset) - 1
# Node after 0
self.child0 = HuffTreeNode.from_rdr(rdr,
zeroIsData,
zeroRelOffset,
max_stream_pos,
parent=self)
# Node after 1 directly located after the node after 0
self.child1 = HuffTreeNode.from_rdr(rdr,
oneIsData,
zeroRelOffset + 1,
max_stream_pos,
parent=self)
# reset stream
rdr.c = currStreamPos
return self
