compression.py

from common import *
		
# Copyright (c) 2008 Hector Martin <marcan@marcansoft.com>
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without modification,
# are permitted provided that the following conditions are met:
#
#     * Redistributions of source code must retain the above copyright notice, this
#       list of conditions and the following disclaimer.
#     * Redistributions in binary form must reproduce the above copyright notice,
#       this list of conditions and the following disclaimer in the documentation
#       and/or other materials provided with the distribution.
#     * The name of the author may not be used to endorse or promote products derived
#       from this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
# EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
# IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
# INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
# NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
# PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
# WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.


class LZ77(WiiHeader):
	class WiiLZ77: # class by marcan, used under scope of BSD license
		TYPE_LZ77 = 1
		def __init__(self, file, offset):
			self.file = file
			self.offset = offset
 
			self.file.seek(self.offset)
 
			hdr = struct.unpack("<I",self.file.read(4))[0]
			self.uncompressed_length = hdr>>8
			self.compression_type = hdr>>4 & 0xF
 
			if self.compression_type != self.TYPE_LZ77:
				raise ValueError("Unsupported compression method %d"%self.compression_type)
 
		def uncompress(self):
			dout = ""
 
			self.file.seek(self.offset + 0x4)
 
			while len(dout) < self.uncompressed_length:
				flags = struct.unpack("<B",self.file.read(1))[0]
 
				for i in range(8):
					if flags & 0x80:
						info = struct.unpack(">H",self.file.read(2))[0]
						num = 3 + ((info>>12)&0xF)
						disp = info & 0xFFF
						ptr = len(dout) - (info & 0xFFF) - 1
						for i in range(num):
							dout += dout[ptr]
							ptr+=1
							if len(dout) >= self.uncompressed_length:
								break
					else:
						dout += self.file.read(1)
					flags <<= 1
					if len(dout) >= self.uncompressed_length:
						break
			self.data = dout
			return self.data
	def remove(self):
 		hdr = self.data[:4]
 		if hdr != "LZ77":
 			return self.data
		file = StringIO(self.data)
		file.seek(4)
		unc = self.WiiLZ77(file, file.tell())
		data = unc.uncompress()
		
		return data
	def compress(self, fn = ""):
		raise NotImplementedError