trace-hash-local.h

/*
 * Copyright (C) 2009, Steven Rostedt <srostedt@redhat.com>
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2 of the License (not later!)
 *
 * 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 General Public License
 * along with this program; if not,  see <http://www.gnu.org/licenses>
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 */
#ifndef _TRACE_HASH_LOCAL_H
#define _TRACE_HASH_LOCAL_H

static inline unsigned int trace_hash(int val)
{
	int hash, tmp;

	hash = 12546869;	/* random prime */

	/*
	 * The following hash is based off of Paul Hsieh's super fast hash:
	 *  http://www.azillionmonkeys.com/qed/hash.html
	 * Note, he released this code unde the GPL 2.0 license, which
	 *  is the same as the license for the programs that use it here.
	 */

	hash +=	(val & 0xffff);
	tmp = (val >> 16) ^ hash;
	hash = (hash << 16) ^ tmp;
	hash += hash >> 11;

	hash ^= hash << 3;
	hash += hash >> 5;
	hash ^= hash << 4;
	hash += hash >> 17;
	hash ^= hash << 25;
	hash += hash >> 6;

	return hash;
}

#endif /* _TRACE_HASH_LOCAL_H */