/*
* opencog/persist/api/DispathcHash.h
*
* Copyright (C) 2025 Linas Vepstas
* All Rights Reserved
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License v3 as
* published by the Free Software Foundation and including the exceptions
* at http://opencog.org/wiki/Licenses
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program; if not, write to:
* Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#ifndef _OPENCOG_DISPATCH_HASH_H
#define _OPENCOG_DISPATCH_HASH_H
#include <string>
namespace opencog
{
/// Implement Jenkins' One-at-a-Time hash.
/// For these very short strings, I cannot think of a faster hash.
/// The 4-byte-at-a-time hashes require knowng the string length :-(
static constexpr uint32_t dispatch_hash(const char* s)
{
uint32_t hash = 0;
for(; *s; ++s)
{
hash += *s;
hash += (hash << 10);
hash ^= (hash >> 6);
}
hash += (hash << 3);
hash ^= (hash >> 11);
hash += (hash << 15);
return hash;
}
} // namespace opencog
#endif // _OPENCOG_DISPATCH_HASH_H