// Hash modified by Robert Heckendorn based on work 
// By Arash Partow (http://www.partow.net/programming/hashfunctions/)
//
// An algorithm produced by me Arash Partow. I took ideas from all of
// the above hash functions making a hybrid rotative and additive hash
// function algorithm based around four primes 3,5,7 and 11.  There isn't
// any real mathematical analysis explaining why one should use this
// hash function instead of the others described above other than the
// fact that I tired to resemble the design as close as possible to a
// simple LFBSR.  An empirical result which demonstrated the distributive
// abilities of the hash algorithm was obtained using a hash-table with
// 100003 buckets, hashing The Project Gutenberg Etext of Webster's
// Unabridged Dictionary, the longest encountered chain length was 7,
// the average chain length was 2, the number of empty buckets was 4579.
unsigned int hash(const char *str)
{
    unsigned int hash;
    char c;

    hash = 0;
    for (bool toggle = false; c = *str++; toggle = !toggle) {
        if (toggle)
            hash ^= (hash << 7)^c^(hash >> 3);
        else
            hash ^= ~(hash << 11)^c^(hash >> 5);
    }

    return hash;
}