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(I'm so sorry!) Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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C
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#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(__ASSEMBLER__)
/* * 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(__ASSEMBLER__) */
/* * 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(__ASSEMBLER__) */
#endif /* __LINUX_BITS_H */