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/* $NetBSD: log2.h,v 1.1 2020/02/16 07:29:48 riastradh Exp $ */
/*-
* Copyright (c) 2013 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Taylor R. Campbell.
*
* 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, 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 NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``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 FOUNDATION OR CONTRIBUTORS
* 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 _LINUX_LOG2_H_
#define _LINUX_LOG2_H_
#include <sys/types.h>
#include <sys/bitops.h>
#include <machine/limits.h>
static inline bool
is_power_of_2(unsigned long x)
{
return ((x != 0) && (((x - 1) & x) == 0));
}
static inline unsigned long
roundup_pow_of_two(unsigned long n)
{
unsigned i;
if (n == 0)
return 1;
n -= 1;
for (i = 1; i < CHAR_BIT * sizeof n; i <<= 1)
n |= (n >> i);
return (n + 1);
}
static inline unsigned long
rounddown_pow_of_two(unsigned long n)
{
/* XXX fls64 is not fls_ulong, but it'll do for now. */
return (1UL << (fls64(n) - 1));
}
static inline unsigned
order_base_2(unsigned long n)
{
return ilog2(roundup_pow_of_two(n));
}
#endif /* _LINUX_LOG2_H_ */
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