Function sdbm_hash

pub unsafe extern "C" fn sdbm_hash(buf: *const u8, len: size_t) -> u32

@defgroup sys_hashes_sdbm sdbm @ingroup sys_hashes_non_crypto @brief sdbm hash algorithm.

HISTORY This algorithm was created for sdbm (a public-domain reimplementation of ndbm) database library. It was found to do well in scrambling bits, causing better distribution of the keys and fewer splits. it also happens to be a good general hashing function with good distribution.

The actual function is

 hash(i) = hash(i - 1) * 65599 + str[i];

What is included below is the faster version used in gawk. [there is even a faster, duff-device version] the magic constant 65599 was picked out of thin air while experimenting with different constants, and turns out to be a prime. this is one of the algorithms used in berkeley db (see sleepycat) and elsewhere.

@param buf input buffer to hash @param len length of buffer @return 32 bit sized hash