Mercurial > touhou

comparison pytouhou/utils/lzss.pyx @ 368:71cd4461bb7f

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Minor optimizations
author Thibaut Girka <thib@sitedethib.com>
date Wed, 11 Jul 2012 15:19:44 +0200
parents 2674c789e0c3
children 1b532e7dd521
comparison
equal deleted inserted replaced
367:2674c789e0c3 368:71cd4461bb7f
20 unsigned int dictionary_size=0x2000, 20 unsigned int dictionary_size=0x2000,
21 unsigned int offset_size=13, 21 unsigned int offset_size=13,
22 unsigned int length_size=4, 22 unsigned int length_size=4,
23 unsigned int minimum_match_length=3): 23 unsigned int minimum_match_length=3):
24 cdef unsigned int i, ptr, dictionary_head, offset, length 24 cdef unsigned int i, ptr, dictionary_head, offset, length
25 cdef unsigned char byte, *out_data, *dictionary 25 cdef unsigned char byte
26 cdef char *out_data, *dictionary
26 cdef bytes _out_data 27 cdef bytes _out_data
27 28
28 out_data = <unsigned char*> malloc(size) 29 out_data = <char*> malloc(size)
29 dictionary = <unsigned char*> calloc(dictionary_size, 1) 30 dictionary = <char*> calloc(dictionary_size, 1)
30 dictionary_head, ptr = 1, 0 31 dictionary_head, ptr = 1, 0
31 32
32 while ptr < size: 33 while ptr < size:
33 if bitstream.read_bit(): 34 if bitstream.read_bit():
34 # The `flag` bit is set, indicating the upcoming chunk of data is a literal 35 # The `flag` bit is set, indicating the upcoming chunk of data is a literal
40 ptr += 1 41 ptr += 1
41 else: 42 else:
42 # The `flag` bit is not set, the upcoming chunk is a (offset, length) tuple 43 # The `flag` bit is not set, the upcoming chunk is a (offset, length) tuple
43 offset = bitstream.read(offset_size) 44 offset = bitstream.read(offset_size)
44 length = bitstream.read(length_size) + minimum_match_length 45 length = bitstream.read(length_size) + minimum_match_length
46 if ptr + length > size:
47 raise Exception
45 if offset == 0 and length == 0: 48 if offset == 0 and length == 0:
46 break 49 break
47 for i in range(offset, offset + length): 50 for i in range(offset, offset + length):
48 out_data[ptr % size] = dictionary[i % dictionary_size] 51 out_data[ptr] = dictionary[i % dictionary_size]
49 ptr += 1
50 dictionary[dictionary_head] = dictionary[i % dictionary_size] 52 dictionary[dictionary_head] = dictionary[i % dictionary_size]
51 dictionary_head = (dictionary_head + 1) % dictionary_size 53 dictionary_head = (dictionary_head + 1) % dictionary_size
54 ptr += 1
52 55
53 _out_data = out_data[:size] 56 _out_data = out_data[:size]
54 free(out_data) 57 free(out_data)
55 free(dictionary) 58 free(dictionary)
56 return _out_data 59 return _out_data