| // Copyright 2011 Google Inc. All Rights Reserved. |
| // |
| // The core Jenkins Lookup2-based hashing routines. These are legacy hashing |
| // routines and should be avoided in new code. Their implementations are dated |
| // and cannot be changed due to values being recorded and breaking if not |
| // preserved. New code which explicitly desires this property should use the |
| // consistent hashing libraries. New code which does not explicitly desire this |
| // behavior should use the generic hashing routines in hash.h. |
| |
| #ifndef UTIL_HASH_JENKINS_H_ |
| #define UTIL_HASH_JENKINS_H_ |
| |
| #include "gutil/integral_types.h" |
| |
| // ---------------------------------------------------------------------- |
| // Hash32StringWithSeed() |
| // Hash64StringWithSeed() |
| // Hash32NumWithSeed() |
| // Hash64NumWithSeed() |
| // These are Bob Jenkins' hash functions, one for 32 bit numbers |
| // and one for 64 bit numbers. Each takes a string as input and |
| // a start seed. Hashing the same string with two different seeds |
| // should give two independent hash values. |
| // The *Num*() functions just do a single mix, in order to |
| // convert the given number into something *random*. |
| // |
| // Note that these methods may return any value for the given size, while |
| // the corresponding HashToXX() methods avoids certain reserved values. |
| // ---------------------------------------------------------------------- |
| |
| // These slow down a lot if inlined, so do not inline them --Sanjay |
| uint32 Hash32StringWithSeed(const char *s, uint32 len, uint32 c); |
| uint64 Hash64StringWithSeed(const char *s, uint32 len, uint64 c); |
| |
| // This is a reference implementation of the same fundamental algorithm as |
| // Hash32StringWithSeed. It is used primarily as a performance metric. |
| uint32 Hash32StringWithSeedReferenceImplementation(const char *s, |
| uint32 len, uint32 c); |
| |
| #endif // UTIL_HASH_JENKINS_H_ |
