1 /* LzHash.h -- HASH constants for LZ algorithms 2 2023-03-05 : 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