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| author | 11rcombs <rodger.combs@gmail.com> | 2014-01-24 02:09:46 +0100 |
|---|---|---|
| committer | Grigori Goronzy <greg@chown.ath.cx> | 2014-01-25 02:22:47 +0100 |
| commit | 975d277b37e3bb8fb3d56ca20a906f4171703d00 (patch) | |
| tree | 335b26761366c8727a3311921b925129a0a1e1b0 | |
| parent | 1f57d903bb63389f5ce279957fd8992a981aaafe (diff) | |
| download | libass-975d277b37e3bb8fb3d56ca20a906f4171703d00.tar.bz2 libass-975d277b37e3bb8fb3d56ca20a906f4171703d00.tar.xz | |
Simplify hash function
We can rely on fast multiplication and good compilers.
v2: use default FNV-1a prime
Signed-off-by: wm4 <wm4@nowhere>
Signed-off-by: Grigori Goronzy <greg@chown.ath.cx>
| -rw-r--r-- | libass/ass_utils.h | 11 |
1 files changed, 4 insertions, 7 deletions
diff --git a/libass/ass_utils.h b/libass/ass_utils.h index e5e0ecd..b797c8c 100644 --- a/libass/ass_utils.h +++ b/libass/ass_utils.h @@ -119,7 +119,8 @@ static inline int rot_key(double a) return double_to_d22(a) % m; } -#define FNV1_32A_INIT (unsigned)0x811c9dc5 +#define FNV1_32A_INIT 0x811c9dc5U +#define FNV1_32A_PRIME 16777619U static inline unsigned fnv_32a_buf(void *buf, size_t len, unsigned hval) { @@ -127,9 +128,7 @@ static inline unsigned fnv_32a_buf(void *buf, size_t len, unsigned hval) unsigned char *be = bp + len; while (bp < be) { hval ^= (unsigned) *bp++; - hval += - (hval << 1) + (hval << 4) + (hval << 7) + (hval << 8) + - (hval << 24); + hval *= FNV1_32A_PRIME; } return hval; } @@ -138,9 +137,7 @@ static inline unsigned fnv_32a_str(char *str, unsigned hval) unsigned char *s = (unsigned char *) str; while (*s) { hval ^= (unsigned) *s++; - hval += - (hval << 1) + (hval << 4) + (hval << 7) + (hval << 8) + - (hval << 24); + hval *= FNV1_32A_PRIME; } return hval; } |