数据压缩：完全参考

G-Spider

http://www.davidsalomon.name/DC4advertis/DComp4Ad.html http://download.csdn.net/source/2082674

wayne

1# G-Spider 在http://library.nu 里搜到了该书的链接，不用注册即可下载： http://ifile.it/ihk7pbj/_eIhbVGtED68.7z

G-Spider

上书也提到了一点关于LZMA，（Lempel-Ziv-Markov chain-Algorithm的缩写），是一个Deflate和LZ77算法改良和优化后的压缩算法，开发者是Igor Pavlov 可以到http://www.7-zip.org/ 下载到SDK。 可以在LzmaLib.h找到压缩LzmaCompress与解压缩LzmaUncompress的接口说明。 LZMA格式的解压，依赖Alloc.c , LzmaDec.c, LzmaLib.c, LzmaLib.h ,Types.h ,LzmaDec.h ,Alloc.h这7个文件再加上自己写的main函数就可以集成解压。

1. /*
2. LzmaCompress
3. ------------
5. outPropsSize -
6. In: the pointer to the size of outProps buffer; *outPropsSize = LZMA_PROPS_SIZE = 5.
7. Out: the pointer to the size of written properties in outProps buffer; *outPropsSize = LZMA_PROPS_SIZE = 5.
9. LZMA Encoder will use defult values for any parameter, if it is
10. -1 for any from: level, loc, lp, pb, fb, numThreads
11. 0 for dictSize
13. level - compression level: 0 <= level <= 9;
15. level dictSize algo fb
16. 0: 16 KB 0 32
17. 1: 64 KB 0 32
18. 2: 256 KB 0 32
19. 3: 1 MB 0 32
20. 4: 4 MB 0 32
21. 5: 16 MB 1 32
22. 6: 32 MB 1 32
23. 7+: 64 MB 1 64
25. The default value for "level" is 5.
27. algo = 0 means fast method
28. algo = 1 means normal method
30. dictSize - The dictionary size in bytes. The maximum value is
31. 128 MB = (1 << 27) bytes for 32-bit version
32. 1 GB = (1 << 30) bytes for 64-bit version
33. The default value is 16 MB = (1 << 24) bytes.
34. It's recommended to use the dictionary that is larger than 4 KB and
35. that can be calculated as (1 << N) or (3 << N) sizes.
37. lc - The number of literal context bits (high bits of previous literal).
38. It can be in the range from 0 to 8. The default value is 3.
39. Sometimes lc=4 gives the gain for big files.
41. lp - The number of literal pos bits (low bits of current position for literals).
42. It can be in the range from 0 to 4. The default value is 0.
43. The lp switch is intended for periodical data when the period is equal to 2^lp.
44. For example, for 32-bit (4 bytes) periodical data you can use lp=2. Often it's
45. better to set lc=0, if you change lp switch.
47. pb - The number of pos bits (low bits of current position).
48. It can be in the range from 0 to 4. The default value is 2.
49. The pb switch is intended for periodical data when the period is equal 2^pb.
51. fb - Word size (the number of fast bytes).
52. It can be in the range from 5 to 273. The default value is 32.
53. Usually, a big number gives a little bit better compression ratio and
54. slower compression process.
56. numThreads - The number of thereads. 1 or 2. The default value is 2.
57. Fast mode (algo = 0) can use only 1 thread.
59. Out:
60. destLen - processed output size
61. Returns:
62. SZ_OK - OK
63. SZ_ERROR_MEM - Memory allocation error
64. SZ_ERROR_PARAM - Incorrect paramater
65. SZ_ERROR_OUTPUT_EOF - output buffer overflow
66. SZ_ERROR_THREAD - errors in multithreading functions (only for Mt version)
67. */
69. MY_STDAPI LzmaCompress(unsigned char *dest, size_t *destLen, const unsigned char *src, size_t srcLen,
70. unsigned char *outProps, size_t *outPropsSize, /* *outPropsSize must be = 5 */
71. int level, /* 0 <= level <= 9, default = 5 */
72. unsigned dictSize, /* default = (1 << 24) */
73. int lc, /* 0 <= lc <= 8, default = 3 */
74. int lp, /* 0 <= lp <= 4, default = 0 */
75. int pb, /* 0 <= pb <= 4, default = 2 */
76. int fb, /* 5 <= fb <= 273, default = 32 */
77. int numThreads /* 1 or 2, default = 2 */
78. );
80. /*
81. LzmaUncompress
82. --------------
83. In:
84. dest - output data
85. destLen - output data size
86. src - input data
87. srcLen - input data size
88. Out:
89. destLen - processed output size
90. srcLen - processed input size
91. Returns:
92. SZ_OK - OK
93. SZ_ERROR_DATA - Data error
94. SZ_ERROR_MEM - Memory allocation arror
95. SZ_ERROR_UNSUPPORTED - Unsupported properties
96. SZ_ERROR_INPUT_EOF - it needs more bytes in input buffer (src)
97. */
99. MY_STDAPI LzmaUncompress(unsigned char *dest, size_t *destLen, const unsigned char *src, SizeT *srcLen,
100. const unsigned char *props, size_t propsSize);

复制代码

上面两个函数的src串的长度是确定的，而dest串的长度是通过返回得到的。 压缩与解压缩.zip (380.64 KB, 下载次数: 16)

2011-2-26 11:22 上传

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解压集成.zip (245.27 KB, 下载次数: 3)

2011-2-26 11:22 上传

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qianyb

2#的需要解压密码，请问解压密码是多少？ 默认都是 library.nu 的 不是啊

wayne

3# G-Spider 我只知道rle 压缩

wayne

4# qianyb 默认都是 library.nu 的

仙剑魔

除了PAQ,现在别的我都不感兴趣了...

G-Spider

7# 仙剑魔 我想PAQ“高压缩”背后的时间代价是最大的隐痛，以前我试过很多PAQ系列，深有体会。当前，从资源角度，相对的高压缩率和用时极少才是热捧的对象。 当然，如果LS的能够解决时间效率问题，你会出名的。

wayne

4# qianyb 无意间发现你这个帖子更新了。 才意识到我没有回复你，莫怪啊 现给出一个无需密码的链接 http://ifile.it/jsn5bh/ebooksclu ... _Fourth_Edition.pdf

qianyb

没注意到正常的，谢谢你了