bitops.h

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/*
 * Copyright 1995, Russell King.
 * Various bits and pieces copyrights include:
 *  Linus Torvalds (test_bit).
 *
 * bit 0 is the LSB of addr; bit 32 is the LSB of (addr+1).
 *
 * Please note that the code in this file should never be included
 * from user space.  Many of these are not implemented in assembler
 * since they would be too costly.  Also, they require priviledged
 * instructions (which are not available from user mode) to ensure
 * that they are atomic.
 */

#ifndef __ASM_ARM_BITOPS_H
#define __ASM_ARM_BITOPS_H

#ifdef __KERNEL__

#define smp_mb__before_clear_bit()	do { } while (0)
#define smp_mb__after_clear_bit()	do { } while (0)

/*
 * Function prototypes to keep gcc -Wall happy.
 */
extern void set_bit(int nr, volatile void * addr);

static inline void __set_bit(int nr, volatile void *addr)
{
	((unsigned char *) addr)[nr >> 3] |= (1U << (nr & 7));
}

extern void clear_bit(int nr, volatile void * addr);

static inline void __clear_bit(int nr, volatile void *addr)
{
	((unsigned char *) addr)[nr >> 3] &= ~(1U << (nr & 7));
}

extern void change_bit(int nr, volatile void * addr);

static inline void __change_bit(int nr, volatile void *addr)
{
	((unsigned char *) addr)[nr >> 3] ^= (1U << (nr & 7));
}

extern int test_and_set_bit(int nr, volatile void * addr);

static inline int __test_and_set_bit(int nr, volatile void *addr)
{
	unsigned int mask = 1 << (nr & 7);
	unsigned int oldval;

	oldval = ((unsigned char *) addr)[nr >> 3];
	((unsigned char *) addr)[nr >> 3] = oldval | mask;
	return oldval & mask;
}

extern int test_and_clear_bit(int nr, volatile void * addr);

static inline int __test_and_clear_bit(int nr, volatile void *addr)
{
	unsigned int mask = 1 << (nr & 7);
	unsigned int oldval;

	oldval = ((unsigned char *) addr)[nr >> 3];
	((unsigned char *) addr)[nr >> 3] = oldval & ~mask;
	return oldval & mask;
}

extern int test_and_change_bit(int nr, volatile void * addr);

static inline int __test_and_change_bit(int nr, volatile void *addr)
{
	unsigned int mask = 1 << (nr & 7);
	unsigned int oldval;

	oldval = ((unsigned char *) addr)[nr >> 3];
	((unsigned char *) addr)[nr >> 3] = oldval ^ mask;
	return oldval & mask;
}

extern int find_first_zero_bit(void * addr, unsigned size);
extern int find_next_zero_bit(void * addr, int size, int offset);

/*
 * This routine doesn't need to be atomic.
 */
static inline int test_bit(int nr, const void * addr)
{
    return ((unsigned char *) addr)[nr >> 3] & (1U << (nr & 7));
}

/*
 * ffz = Find First Zero in word. Undefined if no zero exists,
 * so code should check against ~0UL first..
 */
static inline unsigned long ffz(unsigned long word)
{
	int k;

	word = ~word;
	k = 31;
	if (word & 0x0000ffff) { k -= 16; word <<= 16; }
	if (word & 0x00ff0000) { k -= 8;  word <<= 8;  }
	if (word & 0x0f000000) { k -= 4;  word <<= 4;  }
	if (word & 0x30000000) { k -= 2;  word <<= 2;  }
	if (word & 0x40000000) { k -= 1; }
	return k;
}

/*
 * ffs: find first bit set. This is defined the same way as
 * the libc and compiler builtin ffs routines, therefore
 * differs in spirit from the above ffz (man ffs).
 */

#define ffs(x) generic_ffs(x)

/*
 * hweightN: returns the hamming weight (i.e. the number
 * of bits set) of a N-bit word
 */

#define hweight32(x) generic_hweight32(x)
#define hweight16(x) generic_hweight16(x)
#define hweight8(x) generic_hweight8(x)

#define ext2_set_bit			test_and_set_bit
#define ext2_clear_bit			test_and_clear_bit
#define ext2_test_bit			test_bit
#define ext2_find_first_zero_bit	find_first_zero_bit
#define ext2_find_next_zero_bit		find_next_zero_bit

/* Bitmap functions for the minix filesystem. */
#define minix_test_and_set_bit(nr,addr)	test_and_set_bit(nr,addr)
#define minix_set_bit(nr,addr)		set_bit(nr,addr)
#define minix_test_and_clear_bit(nr,addr)	test_and_clear_bit(nr,addr)
#define minix_test_bit(nr,addr)		test_bit(nr,addr)
#define minix_find_first_zero_bit(addr,size)	find_first_zero_bit(addr,size)

#endif /* __KERNEL__ */

#endif /* _ARM_BITOPS_H */