6 //#define ENABLE_LZX_DEBUG
7 #ifdef ENABLE_LZX_DEBUG
8 # define LZX_DEBUG DEBUG
10 # define LZX_DEBUG(format, ...)
13 /* Constants, most of which are defined by the LZX specification: */
15 /* The smallest and largest allowed match lengths. */
16 #define LZX_MIN_MATCH 2
17 #define LZX_MAX_MATCH 257
19 /* Number of values an uncompressed literal byte can represent. */
20 #define LZX_NUM_CHARS 256
22 /* Each LZX block begins with 3 bits that determines the block type. Below are
23 * the valid block types. Values 0, and 4 through 7, are invalid. */
24 #define LZX_BLOCKTYPE_VERBATIM 1
25 #define LZX_BLOCKTYPE_ALIGNED 2
26 #define LZX_BLOCKTYPE_UNCOMPRESSED 3
28 #define LZX_NUM_PRIMARY_LENS 7 /* this one missing from spec! */
30 /* NOTE: There are really 51 position slots in the LZX format as a whole, but
31 * only 30 are needed to allow for the window to be up to 32768 bytes long,
32 * which is the maximum in the WIM format. */
33 #define LZX_NUM_POSITION_SLOTS 30
35 /* Read the LZX specification for information about the Huffman trees used in
36 * the LZX compression format. Basically there are 4 of them: The main tree,
37 * the length tree, the pre tree, and the aligned tree. The main tree and
38 * length tree are given at the beginning of VERBATIM and ALIGNED blocks as a
39 * list of *_NUM_SYMBOLS code length values. They are read using the
40 * read_code_lens() function and built using the make_decode_table() function.
41 * The decode table is not a real tree but rather a table that we can index by
42 * some number of bits (*_TABLEBITS) of the input to quickly look up the symbol
43 * corresponding to a Huffman code.
45 * The ALIGNED tree is only present on ALIGNED blocks.
47 * A PRETREE is used to encode the code lengths for the main tree and the length
48 * tree. There is a separate pretree for each half of the main tree. */
50 #define LZX_MAINTREE_NUM_SYMBOLS (LZX_NUM_CHARS + \
51 (LZX_NUM_POSITION_SLOTS << 3))
52 #define LZX_MAINTREE_TABLEBITS 12
54 #define LZX_LENTREE_NUM_SYMBOLS 249
55 #define LZX_LENTREE_TABLEBITS 12
57 #define LZX_PRETREE_NUM_SYMBOLS 20
58 #define LZX_PRETREE_TABLEBITS 6
59 #define LZX_PRETREE_ELEMENT_SIZE 4
61 #define LZX_ALIGNEDTREE_NUM_SYMBOLS 8
62 #define LZX_ALIGNEDTREE_TABLEBITS 7
63 #define LZX_ALIGNEDTREE_ELEMENT_SIZE 3
65 /* Maximum allowed length of a Huffman code. */
66 #define LZX_MAX_CODEWORD_LEN 16
68 /* For the LZX-compressed blocks in WIM files, this value is always used as the
69 * filesize parameter for the call instruction (0xe8 byte) preprocessing, even
70 * though the blocks themselves are not this size, and the size of the actual
71 * file resource in the WIM file is very likely to be something entirely
72 * different as well. */
73 #define LZX_MAGIC_FILESIZE 12000000
75 extern const u8 lzx_extra_bits[LZX_NUM_POSITION_SLOTS];
76 extern const u32 lzx_position_base[LZX_NUM_POSITION_SLOTS];
78 /* Least-recently used queue for match offsets. */
85 extern int lzx_decompress(const void *compressed_data, uint compressed_len,
86 void *uncompressed_data, uint uncompressed_len);
88 extern int lzx_compress(const void *uncompressed_data, uint uncompressed_len,
89 void *compressed_data, uint *compressed_len_ret);
91 #endif /* _WIMLIB_LZX_H */