/*
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2022 NVIDIA corporation & affiliates.
 * Copyright (c) 2013 François Tigeot
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice unmodified, this list of conditions, and the following
 *    disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef _LINUXKPI_LINUX_HASH_H_
#define	_LINUXKPI_LINUX_HASH_H_

#include <sys/hash.h>
#include <sys/param.h>
#include <sys/systm.h>

#include <asm/types.h>

#include <linux/bitops.h>

static inline u64
hash_64(u64 val, u8 bits)
{
	u64 ret;
	u8 x;

	ret = bits;

	for (x = 0; x != sizeof(ret); x++) {
		u64 chunk = (val >> (8 * x)) & 0xFF;
		ret = HASHSTEP(ret, chunk);
	}
	return (ret >> (64 - bits));
}

static inline u32
hash_32(u32 val, u8 bits)
{
	u32 ret;
	u8 x;

	ret = bits;

	for (x = 0; x != sizeof(ret); x++) {
		u32 chunk = (val >> (8 * x)) & 0xFF;
		ret = HASHSTEP(ret, chunk);
	}
	return (ret >> (32 - bits));
}

#if BITS_PER_LONG == 64
#define	hash_long(...) hash_64(__VA_ARGS__)
#else
#define	hash_long(...) hash_32(__VA_ARGS__)
#endif

#endif					/* _LINUXKPI_LINUX_HASH_H_ */