1/*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2020 The FreeBSD Foundation
5 *
6 * This software was developed by Mark Johnston under sponsorship from
7 * the FreeBSD Foundation.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions are
11 * met:
12 * 1. Redistributions of source code must retain the above copyright
13 *    notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 *    notice, this list of conditions and the following disclaimer in
16 *    the documentation and/or other materials provided with the distribution.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 */
30
31#ifndef __SYS__BLOCKCOUNT_H__
32#define	__SYS__BLOCKCOUNT_H__
33
34#include <machine/atomic.h>
35
36typedef struct _blockcount {
37	unsigned int	__count;
38} blockcount_t;
39
40#define	_BLOCKCOUNT_WAITERS_FLAG	(1U << 31)
41#define	_BLOCKCOUNT_COUNT(c)		((c) & ~_BLOCKCOUNT_WAITERS_FLAG)
42#define	_BLOCKCOUNT_WAITERS(c)		(((c) & _BLOCKCOUNT_WAITERS_FLAG) != 0)
43
44static inline unsigned int
45blockcount_read(blockcount_t *count)
46{
47	return (_BLOCKCOUNT_COUNT(atomic_load_int(&count->__count)));
48}
49
50#endif /* !__SYS__BLOCKCOUNT_H__ */
51