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pydelzo.py
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pydelzo.py
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#!/usr/bin/env python
#
# This program uses code translated from Java code of Java-LZO compression
# program by Markus Oberhumer, author of LZO algorithm and its implementation
#
# http://www.oberhumer.com/opensource/lzo/
#
# Copyright (C) 1999 Markus Franz Xaver Johannes Oberhumer
# Copyright (C) 1998 Markus Franz Xaver Johannes Oberhumer
# Copyright (C) 1997 Markus Franz Xaver Johannes Oberhumer
# Copyright (C) 1996 Markus Franz Xaver Johannes Oberhumer
#
# The LZO library is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License as
# published by the Free Software Foundation; either version 2 of
# the License, or (at your option) any later version.
#
# The LZO library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with the LZO library; see the file COPYING.
# If not, write to the Free Software Foundation, Inc.,
# 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
#
# Markus F.X.J. Oberhumer
# http://wildsau.idv.uni-linz.ac.at/mfx/lzo.html
#
#
#
# Translation into Python by AMMOnium <ammonium at mail dot ru>
#
from struct import pack, unpack
class LZO_ERROR(Exception):
ed = {0:'LZO_E_OK', \
-1:'LZO_E_ERROR', \
-2:'LZO_E_OUT_OF_MEMORY', \
-3:'LZO_E_NOT_COMPRESSIBLE', \
-4:'LZO_E_INPUT_OVERRUN', \
-5:'LZO_E_OUTPUT_OVERRUN', \
-6:'LZO_E_LOOKBEHIND_OVERRUN', \
-7:'LZO_E_EOF_NOT_FOUND', \
-8:'LZO_E_INPUT_NOT_CONSUMED'}
def __init__(self, value, pos=0):
self.value = value
self.pos = pos
def __str__(self):
return (repr(self.ed[self.value]) \
+ ' at offset %d [0x%x]' % (self.pos,self.pos))
class pydelzo:
"""Python translation of Java-LZO decompression code"""
__version__ = "0.1"
copyright = "LZO Copyright (C) 1996-1999 Markus F.X.J. Oberhumer "\
LZO_E_OK = 0
LZO_E_ERROR = -1
LZO_E_OUT_OF_MEMORY = -2
LZO_E_NOT_COMPRESSIBLE = -3
LZO_E_INPUT_OVERRUN = -4
LZO_E_OUTPUT_OVERRUN = -5
LZO_E_LOOKBEHIND_OVERRUN = -6
LZO_E_EOF_NOT_FOUND = -7
LZO_E_INPUT_NOT_CONSUMED = -8
@staticmethod
def decompress(buf, strict=False):
"""Perform decompression of a data block"""
# length of uncompressed data
raw_len = unpack('>L', str(buf[1:5]))[0]
dst = bytearray(raw_len)
src_len = len(buf) - 5
dst_len = [0]
dst_off = 0
src_off = 0
src = bytearray(buf[5:]) + bytearray(256)
r = pydelzo.int_decompress(src, src_off, raw_len,
dst, dst_off, dst_len)
# if strict mode is on, die if header had specified more data
# than actually received
if r != pydelzo.LZO_E_OK:
if strict or \
(not strict and r != pydelzo.LZO_E_INPUT_NOT_CONSUMED):
raise LZO_ERROR(r,dst_len[0])
return dst[:min(raw_len,dst_len[0])]
# @profile
@staticmethod
def int_decompress(src, src_off, src_len, dst, dst_off, dst_len):
"""Internal decompression subroutine"""
ip = src_off
op = dst_off
t = src[ip]
ip += 1
if t > 17:
t -= 17
dst[op:op+t] = src[ip:ip+t]
op += t
ip += t
t = src[ip]
ip += 1
if t < 16:
return pydelzo.LZO_E_ERROR;
while True:
lf = False
if t < 16:
if t == 0:
while src[ip] == 0:
t += 255
ip += 1
t += 15 + src[ip]
ip += 1
t += 3
dst[op:op+t] = src[ip:ip+t]
op += t
ip += t
t = src[ip]
ip += 1
if t < 16:
m_pos = op - 0x801 - (t >> 2) - (src[ip] << 2)
ip += 1
if m_pos < dst_off:
t = pydelzo.LZO_E_LOOKBEHIND_OVERRUN
break
t = 3
dst[op:op+t] = src[m_pos:m_pos+t]
op += t
m_pos += t
t = src[ip - 2] & 3
if t == 0:
continue
dst[op:op+t] = src[ip:ip+t]
op += t
ip += t
t = src[ip]
ip += 1
while True:
if t >= 64:
m_pos = op - 1 - ((t >> 2) & 7) - (src[ip] << 3)
ip += 1
t = (t >> 5) - 1
elif t >= 32:
t &= 31
if t == 0:
while src[ip] == 0:
t += 255
ip += 1
t += 31 + src[ip]
ip += 1
m_pos = op - 1 - (src[ip] >> 2)
ip += 1
m_pos -= (src[ip] << 6)
ip += 1
elif t >= 16:
m_pos = op - ((t & 8) << 11)
t &= 7
if t == 0:
while src[ip] == 0:
t += 255
ip += 1
t += 7 + src[ip]
ip += 1
m_pos -= (src[ip] >> 2)
ip += 1
m_pos -= (src[ip] << 6)
ip += 1
if m_pos == op:
lf = True
break
m_pos -= 0x4000
else:
m_pos = op - 1 - (t >> 2) - (src[ip] << 2)
ip += 1
t = 0
if m_pos < dst_off:
t = pydelzo.LZO_E_LOOKBEHIND_OVERRUN
lf = True
break
t += 2
for ii in xrange(t):
dst[op+ii] = dst[m_pos+ii]
op += t
m_pos += t
t = src[ip - 2] & 3
if t == 0:
break
dst[op:op+t] = src[ip:ip+t]
op += t
ip += t
t = src[ip]
ip += 1
if lf:
lf = False
break
else:
t = src[ip]
ip += 1
ip -= src_off
op -= dst_off
dst_len[0] = op
if t < 0:
return t;
if ip < src_len:
return pydelzo.LZO_E_INPUT_NOT_CONSUMED;
if ip > src_len:
return pydelzo.LZO_E_INPUT_OVERRUN;
if t != 1:
return pydelzo.LZO_E_ERROR;
return pydelzo.LZO_E_OK;