1 /* Public domain. */ 2 3 #ifndef _LINUX_HASH_H 4 #define _LINUX_HASH_H 5 6 #include <sys/types.h> 7 8 /* 2^32 * ((sqrt(5) - 1) / 2) from Knuth */ 9 #define GOLDEN_RATIO_32 0x9e3779b9 10 11 static inline uint32_t hash_32(uint32_t val,unsigned int bits)12hash_32(uint32_t val, unsigned int bits) 13 { 14 return (val * GOLDEN_RATIO_32) >> (32 - bits); 15 } 16 17 /* 2^64 * ((sqrt(5) - 1) / 2) from Knuth */ 18 #define GOLDEN_RATIO_64 0x9e3779b97f4a7c16ULL 19 20 static inline uint32_t hash_64(uint64_t val,unsigned int bits)21hash_64(uint64_t val, unsigned int bits) 22 { 23 return (val * GOLDEN_RATIO_64) >> (64 - bits); 24 } 25 26 #ifdef __LP64__ 27 #define hash_long(val, bits) hash_64(val, bits) 28 #else 29 #define hash_long(val, bits) hash_32(val, bits) 30 #endif 31 32 #endif 33