| #ifndef __JHASH_H |
| #define __JHASH_H |
| |
| #define __jhash_mix(a, b, c) \ |
| { \ |
| a -= b; a -= c; a ^= (c>>13); \ |
| b -= c; b -= a; b ^= (a<<8); \ |
| c -= a; c -= b; c ^= (b>>13); \ |
| a -= b; a -= c; a ^= (c>>12); \ |
| b -= c; b -= a; b ^= (a<<16); \ |
| c -= a; c -= b; c ^= (b>>5); \ |
| a -= b; a -= c; a ^= (c>>3); \ |
| b -= c; b -= a; b ^= (a<<10); \ |
| c -= a; c -= b; c ^= (b>>15); \ |
| } |
| |
| |
| /* The golden ration: an arbitrary value */ |
| #define JHASH_GOLDEN_RATIO 0x9e3779b9 |
| |
| /* The most generic version, hashes an arbitrary sequence |
| * of bytes. No alignment or length assumptions are made about |
| * the input key. |
| */ |
| static inline u_int32_t jhash(const void *key, u_int32_t length, u_int32_t initval) |
| { |
| u_int32_t a, b, c, len; |
| const u_int8_t *k = key; |
| |
| len = length; |
| a = b = JHASH_GOLDEN_RATIO; |
| c = initval; |
| |
| while (len >= 12) { |
| a += (k[0] +((u_int32_t)k[1]<<8) +((u_int32_t)k[2]<<16) +((u_int32_t)k[3]<<24)); |
| b += (k[4] +((u_int32_t)k[5]<<8) +((u_int32_t)k[6]<<16) +((u_int32_t)k[7]<<24)); |
| c += (k[8] +((u_int32_t)k[9]<<8) +((u_int32_t)k[10]<<16)+((u_int32_t)k[11]<<24)); |
| |
| __jhash_mix(a,b,c); |
| |
| k += 12; |
| len -= 12; |
| } |
| |
| c += length; |
| switch (len) { |
| case 11: c += ((u_int32_t)k[10]<<24); |
| case 10: c += ((u_int32_t)k[9]<<16); |
| case 9 : c += ((u_int32_t)k[8]<<8); |
| case 8 : b += ((u_int32_t)k[7]<<24); |
| case 7 : b += ((u_int32_t)k[6]<<16); |
| case 6 : b += ((u_int32_t)k[5]<<8); |
| case 5 : b += k[4]; |
| case 4 : a += ((u_int32_t)k[3]<<24); |
| case 3 : a += ((u_int32_t)k[2]<<16); |
| case 2 : a += ((u_int32_t)k[1]<<8); |
| case 1 : a += k[0]; |
| }; |
| |
| __jhash_mix(a,b,c); |
| |
| return c; |
| } |
| |
| static inline u_int32_t jhash_3words(u_int32_t a, u_int32_t b, u_int32_t c, u_int32_t initval) |
| { |
| a += JHASH_GOLDEN_RATIO; |
| b += JHASH_GOLDEN_RATIO; |
| c += initval; |
| |
| __jhash_mix(a, b, c); |
| |
| return c; |
| } |
| |
| static inline u_int32_t jhash_2words(u_int32_t a, u_int32_t b, u_int32_t initval) |
| { |
| return jhash_3words(a, b, 0, initval); |
| } |
| |
| static inline u_int32_t jhash_1word(u_int32_t a, u_int32_t initval) |
| { |
| return jhash_3words(a, 0, 0, initval); |
| } |
| |
| #endif |