| 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 __int128' 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 | /* |
| 54 | * Divide positive or negative dividend by positive or negative divisor |
| 55 | * and round to closest integer. Result is undefined for negative |
| 56 | * divisors if the dividend variable type is unsigned and for negative |
| 57 | * dividends if the divisor variable type is unsigned. |
| 58 | */ |
| 59 | #define __KERNEL_DIV_ROUND_CLOSEST(x, divisor) \ |
| 60 | ({ \ |
| 61 | __typeof__(x) __x = x; \ |
| 62 | __typeof__(divisor) __d = divisor; \ |
| 63 | \ |
| 64 | (((__typeof__(x))-1) > 0 || \ |
| 65 | ((__typeof__(divisor))-1) > 0 || \ |
| 66 | (((__x) > 0) == ((__d) > 0))) ? \ |
| 67 | (((__x) + ((__d) / 2)) / (__d)) : \ |
| 68 | (((__x) - ((__d) / 2)) / (__d)); \ |
| 69 | }) |
| 70 | |
| 71 | #endif /* _LINUX_CONST_H */ |