| … | |
… | |
| 36 | * the hashing function might seem strange, just believe me |
36 | * the hashing function might seem strange, just believe me |
| 37 | * it works ;) |
37 | * it works ;) |
| 38 | */ |
38 | */ |
| 39 | #define FRST(p) (((p[0]) << 8) + p[1]) |
39 | #define FRST(p) (((p[0]) << 8) + p[1]) |
| 40 | #define NEXT(v,p) (((v) << 8) + p[2]) |
40 | #define NEXT(v,p) (((v) << 8) + p[2]) |
| 41 | #define IDX(h) ((((h ^ (h << 4)) >> (3*8 - HLOG)) + h*3) & (HSIZE - 1)) |
41 | #define IDX(h) ((((h ^ (h << 5)) >> (3*8 - HLOG)) + h*3) & (HSIZE - 1)) |
| 42 | /* |
42 | /* |
| 43 | * IDX works because it is very similar to a multiplicative hash, e.g. |
43 | * IDX works because it is very similar to a multiplicative hash, e.g. |
| 44 | * (h * 57321 >> (3*8 - HLOG)) |
44 | * (h * 57321 >> (3*8 - HLOG)) |
| 45 | * the next one is also quite good, albeit slow ;) |
45 | * the next one is also quite good, albeit slow ;) |
| 46 | * (int)(cos(h & 0xffffff) * 1e6) |
46 | * (int)(cos(h & 0xffffff) * 1e6) |
| 47 | */ |
47 | */ |
| 48 | |
48 | |
| 49 | #if 0 |
49 | #if 0 |
| 50 | /* original lzv-like hash function */ |
50 | /* original lzv-like hash function */ |
| 51 | # define FRST(p) (p[0] << 5) ^ p[1] |
51 | # define FRST(p) (p[0] << 5) ^ p[1] |
| 52 | # define NEXT(v,p) (v << 5) ^ p[2] |
52 | # define NEXT(v,p) ((v) << 5) ^ p[2] |
| 53 | # define IDX(h) (h) & (HSIZE - 1) |
53 | # define IDX(h) ((h) & (HSIZE - 1)) |
| 54 | #endif |
54 | #endif |
| 55 | |
55 | |
| 56 | #define MAX_LIT (1 << 5) |
56 | #define MAX_LIT (1 << 5) |
| 57 | #define MAX_OFF (1 << 13) |
57 | #define MAX_OFF (1 << 13) |
| 58 | #define MAX_REF ((1 << 8) + (1 << 3)) |
58 | #define MAX_REF ((1 << 8) + (1 << 3)) |
