cregit-Linux how code gets into the kernel

Release 4.7 tools/testing/radix-tree/linux/bitops.h

#ifndef _ASM_GENERIC_BITOPS_NON_ATOMIC_H_

#define _ASM_GENERIC_BITOPS_NON_ATOMIC_H_

#include <linux/types.h>


#define BITOP_MASK(nr)		(1UL << ((nr) % BITS_PER_LONG))

#define BITOP_WORD(nr)		((nr) / BITS_PER_LONG)

/**
 * __set_bit - Set a bit in memory
 * @nr: the bit to set
 * @addr: the address to start counting from
 *
 * Unlike set_bit(), this function is non-atomic and may be reordered.
 * If it's called on the same region of memory simultaneously, the effect
 * may be that only one operation succeeds.
 */

static inline void __set_bit(int nr, volatile unsigned long *addr) { unsigned long mask = BITOP_MASK(nr); unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr); *p |= mask; }

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static inline void __clear_bit(int nr, volatile unsigned long *addr) { unsigned long mask = BITOP_MASK(nr); unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr); *p &= ~mask; }

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/** * __change_bit - Toggle a bit in memory * @nr: the bit to change * @addr: the address to start counting from * * Unlike change_bit(), this function is non-atomic and may be reordered. * If it's called on the same region of memory simultaneously, the effect * may be that only one operation succeeds. */
static inline void __change_bit(int nr, volatile unsigned long *addr) { unsigned long mask = BITOP_MASK(nr); unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr); *p ^= mask; }

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/** * __test_and_set_bit - Set a bit and return its old value * @nr: Bit to set * @addr: Address to count from * * This operation is non-atomic and can be reordered. * If two examples of this operation race, one can appear to succeed * but actually fail. You must protect multiple accesses with a lock. */
static inline int __test_and_set_bit(int nr, volatile unsigned long *addr) { unsigned long mask = BITOP_MASK(nr); unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr); unsigned long old = *p; *p = old | mask; return (old & mask) != 0; }

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/** * __test_and_clear_bit - Clear a bit and return its old value * @nr: Bit to clear * @addr: Address to count from * * This operation is non-atomic and can be reordered. * If two examples of this operation race, one can appear to succeed * but actually fail. You must protect multiple accesses with a lock. */
static inline int __test_and_clear_bit(int nr, volatile unsigned long *addr) { unsigned long mask = BITOP_MASK(nr); unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr); unsigned long old = *p; *p = old & ~mask; return (old & mask) != 0; }

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/* WARNING: non atomic and it can be reordered! */
static inline int __test_and_change_bit(int nr, volatile unsigned long *addr) { unsigned long mask = BITOP_MASK(nr); unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr); unsigned long old = *p; *p = old ^ mask; return (old & mask) != 0; }

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/** * test_bit - Determine whether a bit is set * @nr: bit number to test * @addr: Address to start counting from */
static inline int test_bit(int nr, const volatile unsigned long *addr) { return 1UL & (addr[BITOP_WORD(nr)] >> (nr & (BITS_PER_LONG-1))); }

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/** * __ffs - find first bit in word. * @word: The word to search * * Undefined if no bit exists, so code should check against 0 first. */
static inline unsigned long __ffs(unsigned long word) { int num = 0; if ((word & 0xffffffff) == 0) { num += 32; word >>= 32; } if ((word & 0xffff) == 0) { num += 16; word >>= 16; } if ((word & 0xff) == 0) { num += 8; word >>= 8; } if ((word & 0xf) == 0) { num += 4; word >>= 4; } if ((word & 0x3) == 0) { num += 2; word >>= 2; } if ((word & 0x1) == 0) num += 1; return num; }

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unsigned long find_next_bit(const unsigned long *addr, unsigned long size, unsigned long offset); #endif /* _ASM_GENERIC_BITOPS_NON_ATOMIC_H_ */

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