const.h (1586B) - Raw
1 /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ 2 /* const.h: Macros for dealing with constants. */ 3 4 #ifndef _LINUX_CONST_H 5 #define _LINUX_CONST_H 6 7 /* Some constant macros are used in both assembler and 8 * C code. Therefore we cannot annotate them always with 9 * 'UL' and other type specifiers unilaterally. We 10 * use the following macros to deal with this. 11 * 12 * Similarly, _AT() will cast an expression with a type in C, but 13 * leave it unchanged in asm. 14 */ 15 16 #ifdef __ASSEMBLY__ 17 #define _AC(X,Y) X 18 #define _AT(T,X) X 19 #else 20 #define __AC(X,Y) (X##Y) 21 #define _AC(X,Y) __AC(X,Y) 22 #define _AT(T,X) ((T)(X)) 23 #endif 24 25 #define _UL(x) (_AC(x, UL)) 26 #define _ULL(x) (_AC(x, ULL)) 27 28 #define _BITUL(x) (_UL(1) << (x)) 29 #define _BITULL(x) (_ULL(1) << (x)) 30 31 #if !defined(__ASSEMBLY__) 32 /* 33 * Missing __asm__ support 34 * 35 * __BIT128() would not work in the __asm__ code, as it shifts an 36 * 'unsigned __init128' data type as direct representation of 37 * 128 bit constants is not supported in the gcc compiler, as 38 * they get silently truncated. 39 * 40 * TODO: Please revisit this implementation when gcc compiler 41 * starts representing 128 bit constants directly like long 42 * and unsigned long etc. Subsequently drop the comment for 43 * GENMASK_U128() which would then start supporting __asm__ code. 44 */ 45 #define _BIT128(x) ((unsigned __int128)(1) << (x)) 46 #endif 47 48 #define __ALIGN_KERNEL(x, a) __ALIGN_KERNEL_MASK(x, (__typeof__(x))(a) - 1) 49 #define __ALIGN_KERNEL_MASK(x, mask) (((x) + (mask)) & ~(mask)) 50 51 #define __KERNEL_DIV_ROUND_UP(n, d) (((n) + (d) - 1) / (d)) 52 53 #endif /* _LINUX_CONST_H */