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;
}

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;
}

/**
 * __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;
}

/**
 * __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;
}

/**
 * __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;
}

/* 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;
}

/**
 * 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)));
}

/**
 * __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;
}

unsigned long find_next_bit(const unsigned long *addr,
			    unsigned long size,
			    unsigned long offset);

#endif /* _ASM_GENERIC_BITOPS_NON_ATOMIC_H_ */