diff options
| -rw-r--r-- | Changes | 3 | ||||
| -rw-r--r-- | lzf_c.c | 8 |
2 files changed, 8 insertions, 3 deletions
@@ -1,3 +1,6 @@ +1.4 + - very very slight tuning of the hashing function. + 1.3 Thu Mar 25 15:41:17 CET 2004 - changed license of lzf core code to explicitly allow relicensing under the GPLv2. @@ -48,16 +48,18 @@ */ #define FRST(p) (((p[0]) << 8) + p[1]) #define NEXT(v,p) (((v) << 8) + p[2]) -#define IDX(h) ((((h ^ (h << 5)) >> (3*8 - HLOG)) + h*3) & (HSIZE - 1)) +#define IDX(h) ((((h ^ (h << 5)) >> (3*8 - HLOG)) - h*5) & (HSIZE - 1)) /* * IDX works because it is very similar to a multiplicative hash, e.g. - * (h * 57321 >> (3*8 - HLOG)) + * ((h * 57321 >> (3*8 - HLOG)) & (HSIZE - 1)) + * the latter is also quite fast on newer CPUs, and sligthly better + * * the next one is also quite good, albeit slow ;) * (int)(cos(h & 0xffffff) * 1e6) */ #if 0 -/* original lzv-like hash function */ +/* original lzv-like hash function, much worse and thus slower */ # define FRST(p) (p[0] << 5) ^ p[1] # define NEXT(v,p) ((v) << 5) ^ p[2] # define IDX(h) ((h) & (HSIZE - 1)) |