xref: /third_party/lzma/C/LzHash.h (revision 370b324c)
1/* LzHash.h -- HASH constants for LZ algorithms
22023-03-05 : Igor Pavlov : Public domain */
3
4#ifndef ZIP7_INC_LZ_HASH_H
5#define ZIP7_INC_LZ_HASH_H
6
7/*
8  (kHash2Size >= (1 <<  8)) : Required
9  (kHash3Size >= (1 << 16)) : Required
10*/
11
12#define kHash2Size (1 << 10)
13#define kHash3Size (1 << 16)
14// #define kHash4Size (1 << 20)
15
16#define kFix3HashSize (kHash2Size)
17#define kFix4HashSize (kHash2Size + kHash3Size)
18// #define kFix5HashSize (kHash2Size + kHash3Size + kHash4Size)
19
20/*
21  We use up to 3 crc values for hash:
22    crc0
23    crc1 << Shift_1
24    crc2 << Shift_2
25  (Shift_1 = 5) and (Shift_2 = 10) is good tradeoff.
26  Small values for Shift are not good for collision rate.
27  Big value for Shift_2 increases the minimum size
28  of hash table, that will be slow for small files.
29*/
30
31#define kLzHash_CrcShift_1 5
32#define kLzHash_CrcShift_2 10
33
34#endif
35