Linux kernel mirror (for testing)
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linux
1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef __LINUX_BITS_H
3#define __LINUX_BITS_H
4
5#include <linux/const.h>
6#include <vdso/bits.h>
7#include <uapi/linux/bits.h>
8#include <asm/bitsperlong.h>
9
10#define BIT_MASK(nr) (UL(1) << ((nr) % BITS_PER_LONG))
11#define BIT_WORD(nr) ((nr) / BITS_PER_LONG)
12#define BIT_ULL_MASK(nr) (ULL(1) << ((nr) % BITS_PER_LONG_LONG))
13#define BIT_ULL_WORD(nr) ((nr) / BITS_PER_LONG_LONG)
14#define BITS_PER_BYTE 8
15
16/*
17 * Create a contiguous bitmask starting at bit position @l and ending at
18 * position @h. For example
19 * GENMASK_ULL(39, 21) gives us the 64bit vector 0x000000ffffe00000.
20 */
21#if !defined(__ASSEMBLY__)
22#include <linux/build_bug.h>
23#include <linux/compiler.h>
24#define GENMASK_INPUT_CHECK(h, l) BUILD_BUG_ON_ZERO(const_true((l) > (h)))
25#else
26/*
27 * BUILD_BUG_ON_ZERO is not available in h files included from asm files,
28 * disable the input check if that is the case.
29 */
30#define GENMASK_INPUT_CHECK(h, l) 0
31#endif
32
33#define GENMASK(h, l) \
34 (GENMASK_INPUT_CHECK(h, l) + __GENMASK(h, l))
35#define GENMASK_ULL(h, l) \
36 (GENMASK_INPUT_CHECK(h, l) + __GENMASK_ULL(h, l))
37
38#if !defined(__ASSEMBLY__)
39/*
40 * Missing asm support
41 *
42 * __GENMASK_U128() depends on _BIT128() which would not work
43 * in the asm code, as it shifts an 'unsigned __init128' data
44 * type instead of direct representation of 128 bit constants
45 * such as long and unsigned long. The fundamental problem is
46 * that a 128 bit constant will get silently truncated by the
47 * gcc compiler.
48 */
49#define GENMASK_U128(h, l) \
50 (GENMASK_INPUT_CHECK(h, l) + __GENMASK_U128(h, l))
51#endif
52
53#endif /* __LINUX_BITS_H */