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#ifndef _LINUX_HASH_H
#define _LINUX_HASH_H
/* Fast hashing routine for ints, longs and pointers.
(C) 2002 William Lee Irwin III, IBM */
/*
* Knuth recommends primes in approximately golden ratio to the maximum
* integer representable by a machine word for multiplicative hashing.
* Chuck Lever verified the effectiveness of this technique:
* http://www.citi.umich.edu/techreports/reports/citi-tr-00-1.pdf
*
* These primes are chosen to be bit-sparse, that is operations on
* them can use shifts and additions instead of multiplications for
* machines where multiplications are slow.
*/
#include <stdint.h>
static inline uint64_t hash_64(const uint64_t val, const unsigned int bits)
{
return (val * 11400714819323198485LLU) >> (64 - bits);
}
#endif /* _LINUX_HASH_H */
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