diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/include/utils/hashutils.h | 16 |
1 files changed, 14 insertions, 2 deletions
diff --git a/src/include/utils/hashutils.h b/src/include/utils/hashutils.h index 366bd0e78bd..3a5c21f5235 100644 --- a/src/include/utils/hashutils.h +++ b/src/include/utils/hashutils.h @@ -8,8 +8,8 @@ #define HASHUTILS_H /* - * Combine two hash values, resulting in another hash value, with decent bit - * mixing. + * Combine two 32-bit hash values, resulting in another hash value, with + * decent bit mixing. * * Similar to boost's hash_combine(). */ @@ -20,6 +20,18 @@ hash_combine(uint32 a, uint32 b) return a; } +/* + * Combine two 64-bit hash values, resulting in another hash value, using the + * same kind of technique as hash_combine(). Testing shows that this also + * produces good bit mixing. + */ +static inline uint64 +hash_combine64(uint64 a, uint64 b) +{ + /* 0x49a0f4dd15e5a8e3 is 64bit random data */ + a ^= b + 0x49a0f4dd15e5a8e3 + (a << 54) + (a >> 7); + return a; +} /* * Simple inline murmur hash implementation hashing a 32 bit integer, for |