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Quelle bits.h Sprache: C |
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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __LINUX_BITS_H #define __LINUX_BITS_H #include <vdso/bits.h> #include <uapi/linux/bits.h> #define BIT_MASK(nr) (UL(1) << ((nr) % BITS_PER_LONG)) #define BIT_WORD(nr) ((nr) / BITS_PER_LONG) #define BIT_ULL_MASK(nr) (ULL(1) << ((nr) % BITS_PER_LONG_LONG)) #define BIT_ULL_WORD(nr) ((nr) / BITS_PER_LONG_LONG) #define BITS_PER_BYTE 8 #define BITS_PER_TYPE(type) (sizeof(type) * BITS_PER_BYTE) /* * Create a contiguous bitmask starting at bit position @l and ending at * position @h. For example * GENMASK_ULL(39, 21) gives us the 64bit vector 0x000000ffffe00000. */ #if !defined(__ASSEMBLY__) /* * Missing asm support * * GENMASK_U*() and BIT_U*() depend on BITS_PER_TYPE() which relies on sizeof(), * something not available in asm. Nevertheless, fixed width integers is a C * concept. Assembly code can rely on the long and long long versions instead. */ #include <linux/build_bug.h> #include <linux/compiler.h> #include <linux/overflow.h> #define GENMASK_INPUT_CHECK(h, l) BUILD_BUG_ON_ZERO(const_true((l) > (h))) /* * Generate a mask for the specified type @t. Additional checks are made to * guarantee the value returned fits in that type, relying on * -Wshift-count-overflow compiler check to detect incompatible arguments. * For example, all these create build errors or warnings: * * - GENMASK(15, 20): wrong argument order * - GENMASK(72, 15): doesn't fit unsigned long * - GENMASK_U32(33, 15): doesn't fit in a u32 */ #define GENMASK_TYPE(t, h, l) \ ((t)(GENMASK_INPUT_CHECK(h, l) + \ (type_max(t) << (l) & \ type_max(t) >> (BITS_PER_TYPE(t) - 1 - (h))))) #define GENMASK(h, l) GENMASK_TYPE(unsigned long, h, l) #define GENMASK_ULL(h, l) GENMASK_TYPE(unsigned long long, h, l) #define GENMASK_U8(h, l) GENMASK_TYPE(u8, h, l) #define GENMASK_U16(h, l) GENMASK_TYPE(u16, h, l) #define GENMASK_U32(h, l) GENMASK_TYPE(u32, h, l) #define GENMASK_U64(h, l) GENMASK_TYPE(u64, h, l) #define GENMASK_U128(h, l) GENMASK_TYPE(u128, h, l) /* * Fixed-type variants of BIT(), with additional checks like GENMASK_TYPE(). The * following examples generate compiler warnings due to -Wshift-count-overflow: * * - BIT_U8(8) * - BIT_U32(-1) * - BIT_U32(40) */ #define BIT_INPUT_CHECK(type, nr) \ BUILD_BUG_ON_ZERO(const_true((nr) >= BITS_PER_TYPE(type))) #define BIT_TYPE(type, nr) ((type)(BIT_INPUT_CHECK(type, nr) + BIT_ULL(nr))) #define BIT_U8(nr) BIT_TYPE(u8, nr) #define BIT_U16(nr) BIT_TYPE(u16, nr) #define BIT_U32(nr) BIT_TYPE(u32, nr) #define BIT_U64(nr) BIT_TYPE(u64, nr) #else /* defined(__ASSEMBLY__) */ /* * BUILD_BUG_ON_ZERO is not available in h files included from asm files, * disable the input check if that is the case. */ #define GENMASK(h, l) __GENMASK(h, l) #define GENMASK_ULL(h, l) __GENMASK_ULL(h, l) #endif /* !defined(__ASSEMBLY__) */ #endif /* __LINUX_BITS_H */ ¤ Dauer der Verarbeitung: 0.23 Sekunden (vorverarbeitet) ¤*© Formatika GbR, Deutschland |
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2026-03-28