xref: /linux-6.15/include/uapi/linux/const.h (revision 0312e94a)
16f52b16cSGreg Kroah-Hartman /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
2607ca46eSDavid Howells /* const.h: Macros for dealing with constants.  */
3607ca46eSDavid Howells 
42a6cc8a6SMasahiro Yamada #ifndef _UAPI_LINUX_CONST_H
52a6cc8a6SMasahiro Yamada #define _UAPI_LINUX_CONST_H
6607ca46eSDavid Howells 
7607ca46eSDavid Howells /* Some constant macros are used in both assembler and
8607ca46eSDavid Howells  * C code.  Therefore we cannot annotate them always with
9607ca46eSDavid Howells  * 'UL' and other type specifiers unilaterally.  We
10607ca46eSDavid Howells  * use the following macros to deal with this.
11607ca46eSDavid Howells  *
12607ca46eSDavid Howells  * Similarly, _AT() will cast an expression with a type in C, but
13607ca46eSDavid Howells  * leave it unchanged in asm.
14607ca46eSDavid Howells  */
15607ca46eSDavid Howells 
16607ca46eSDavid Howells #ifdef __ASSEMBLY__
17607ca46eSDavid Howells #define _AC(X,Y)	X
18607ca46eSDavid Howells #define _AT(T,X)	X
19607ca46eSDavid Howells #else
20607ca46eSDavid Howells #define __AC(X,Y)	(X##Y)
21607ca46eSDavid Howells #define _AC(X,Y)	__AC(X,Y)
22607ca46eSDavid Howells #define _AT(T,X)	((T)(X))
23607ca46eSDavid Howells #endif
24607ca46eSDavid Howells 
252dd8a62cSMasahiro Yamada #define _UL(x)		(_AC(x, UL))
262dd8a62cSMasahiro Yamada #define _ULL(x)		(_AC(x, ULL))
272dd8a62cSMasahiro Yamada 
2821e7bc60SMasahiro Yamada #define _BITUL(x)	(_UL(1) << (x))
2921e7bc60SMasahiro Yamada #define _BITULL(x)	(_ULL(1) << (x))
302fc016c5SH. Peter Anvin 
31947697c6SAnshuman Khandual #if !defined(__ASSEMBLY__)
32947697c6SAnshuman Khandual /*
33947697c6SAnshuman Khandual  * Missing asm support
34947697c6SAnshuman Khandual  *
35947697c6SAnshuman Khandual  * __BIT128() would not work in the asm code, as it shifts an
36*0312e94aSVincent Mailhol  * 'unsigned __int128' data type as direct representation of
37947697c6SAnshuman Khandual  * 128 bit constants is not supported in the gcc compiler, as
38947697c6SAnshuman Khandual  * they get silently truncated.
39947697c6SAnshuman Khandual  *
40947697c6SAnshuman Khandual  * TODO: Please revisit this implementation when gcc compiler
41947697c6SAnshuman Khandual  * starts representing 128 bit constants directly like long
42947697c6SAnshuman Khandual  * and unsigned long etc. Subsequently drop the comment for
43947697c6SAnshuman Khandual  * GENMASK_U128() which would then start supporting asm code.
44947697c6SAnshuman Khandual  */
45947697c6SAnshuman Khandual #define _BIT128(x)	((unsigned __int128)(1) << (x))
46947697c6SAnshuman Khandual #endif
47947697c6SAnshuman Khandual 
4831088f6fSKevin Brodsky #define __ALIGN_KERNEL(x, a)		__ALIGN_KERNEL_MASK(x, (__typeof__(x))(a) - 1)
49a85cbe61SPetr Vorel #define __ALIGN_KERNEL_MASK(x, mask)	(((x) + (mask)) & ~(mask))
50a85cbe61SPetr Vorel 
51a85cbe61SPetr Vorel #define __KERNEL_DIV_ROUND_UP(n, d) (((n) + (d) - 1) / (d))
52a85cbe61SPetr Vorel 
532a6cc8a6SMasahiro Yamada #endif /* _UAPI_LINUX_CONST_H */
54