xref: /linux/tools/include/linux/bits.h (revision b50ecc5aca4d18f1f0c4942f5c797bc85edef144)
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 #define GENMASK_INPUT_CHECK(h, l) \
24 	(BUILD_BUG_ON_ZERO(__builtin_choose_expr( \
25 		__is_constexpr((l) > (h)), (l) > (h), 0)))
26 #else
27 /*
28  * BUILD_BUG_ON_ZERO is not available in h files included from asm files,
29  * disable the input check if that is the case.
30  */
31 #define GENMASK_INPUT_CHECK(h, l) 0
32 #endif
33 
34 #define GENMASK(h, l) \
35 	(GENMASK_INPUT_CHECK(h, l) + __GENMASK(h, l))
36 #define GENMASK_ULL(h, l) \
37 	(GENMASK_INPUT_CHECK(h, l) + __GENMASK_ULL(h, l))
38 
39 #if !defined(__ASSEMBLY__)
40 /*
41  * Missing asm support
42  *
43  * __GENMASK_U128() depends on _BIT128() which would not work
44  * in the asm code, as it shifts an 'unsigned __init128' data
45  * type instead of direct representation of 128 bit constants
46  * such as long and unsigned long. The fundamental problem is
47  * that a 128 bit constant will get silently truncated by the
48  * gcc compiler.
49  */
50 #define GENMASK_U128(h, l) \
51 	(GENMASK_INPUT_CHECK(h, l) + __GENMASK_U128(h, l))
52 #endif
53 
54 #endif	/* __LINUX_BITS_H */
55