linux/include/asm-x86_64/bitops.h

#ifndef _X86_64_BITOPS_H
#define _X86_64_BITOPS_H

/*
 * Copyright 1992, Linus Torvalds.
 */

#include <asm/alternative.h>

#if __GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 1)
/* Technically wrong, but this avoids compilation errors on some gcc
   versions. */
#define ADDR "=m" (*(volatile long *) addr)
#else
#define ADDR "+m" (*(volatile long *) addr)
#endif

/**
 * set_bit - Atomically set a bit in memory
 * @nr: the bit to set
 * @addr: the address to start counting from
 *
 * This function is atomic and may not be reordered.  See __set_bit()
 * if you do not require the atomic guarantees.
 * Note that @nr may be almost arbitrarily large; this function is not
 * restricted to acting on a single-word quantity.
 */
static __inline__ void set_bit(int nr, volatile void * addr)
{
	__asm__ __volatile__( LOCK_PREFIX
		"btsl %1,%0"
		:ADDR
		:"dIr" (nr) : "memory");
}

/**
 * __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 void * addr)
{
	__asm__ volatile(
		"btsl %1,%0"
		:ADDR
		:"dIr" (nr) : "memory");
}

/**
 * clear_bit - Clears a bit in memory
 * @nr: Bit to clear
 * @addr: Address to start counting from
 *
 * clear_bit() is atomic and may not be reordered.  However, it does
 * not contain a memory barrier, so if it is used for locking purposes,
 * you should call smp_mb__before_clear_bit() and/or smp_mb__after_clear_bit()
 * in order to ensure changes are visible on other processors.
 */
static __inline__ void clear_bit(int nr, volatile void * addr)
{
	__asm__ __volatile__( LOCK_PREFIX
		"btrl %1,%0"
		:ADDR
		:"dIr" (nr));
}

static __inline__ void __clear_bit(int nr, volatile void * addr)
{
	__asm__ __volatile__(
		"btrl %1,%0"
		:ADDR
		:"dIr" (nr));
}

#define smp_mb__before_clear_bit()	barrier()
#define smp_mb__after_clear_bit()	barrier()

/**
 * __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 void * addr)
{
	__asm__ __volatile__(
		"btcl %1,%0"
		:ADDR
		:"dIr" (nr));
}

/**
 * change_bit - Toggle a bit in memory
 * @nr: Bit to change
 * @addr: Address to start counting from
 *
 * change_bit() is atomic and may not be reordered.
 * Note that @nr may be almost arbitrarily large; this function is not
 * restricted to acting on a single-word quantity.
 */
static __inline__ void change_bit(int nr, volatile void * addr)
{
	__asm__ __volatile__( LOCK_PREFIX
		"btcl %1,%0"
		:ADDR
		:"dIr" (nr));
}

/**
 * test_and_set_bit - Set a bit and return its old value
 * @nr: Bit to set
 * @addr: Address to count from
 *
 * This operation is atomic and cannot be reordered.  
 * It also implies a memory barrier.
 */
static __inline__ int test_and_set_bit(int nr, volatile void * addr)
{
	int oldbit;

	__asm__ __volatile__( LOCK_PREFIX
		"btsl %2,%1\n\tsbbl %0,%0"
		:"=r" (oldbit),ADDR
		:"dIr" (nr) : "memory");
	return oldbit;
}

/**
 * __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 void * addr)
{
	int oldbit;

	__asm__(
		"btsl %2,%1\n\tsbbl %0,%0"
		:"=r" (oldbit),ADDR
		:"dIr" (nr));
	return oldbit;
}

/**
 * test_and_clear_bit - Clear a bit and return its old value
 * @nr: Bit to clear
 * @addr: Address to count from
 *
 * This operation is atomic and cannot be reordered.  
 * It also implies a memory barrier.
 */
static __inline__ int test_and_clear_bit(int nr, volatile void * addr)
{
	int oldbit;

	__asm__ __volatile__( LOCK_PREFIX
		"btrl %2,%1\n\tsbbl %0,%0"
		:"=r" (oldbit),ADDR
		:"dIr" (nr) : "memory");
	return oldbit;
}

/**
 * __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 void * addr)
{
	int oldbit;

	__asm__(
		"btrl %2,%1\n\tsbbl %0,%0"
		:"=r" (oldbit),ADDR
		:"dIr" (nr));
	return oldbit;
}

/* WARNING: non atomic and it can be reordered! */
static __inline__ int __test_and_change_bit(int nr, volatile void * addr)
{
	int oldbit;

	__asm__ __volatile__(
		"btcl %2,%1\n\tsbbl %0,%0"
		:"=r" (oldbit),ADDR
		:"dIr" (nr) : "memory");
	return oldbit;
}

/**
 * test_and_change_bit - Change a bit and return its old value
 * @nr: Bit to change
 * @addr: Address to count from
 *
 * This operation is atomic and cannot be reordered.  
 * It also implies a memory barrier.
 */
static __inline__ int test_and_change_bit(int nr, volatile void * addr)
{
	int oldbit;

	__asm__ __volatile__( LOCK_PREFIX
		"btcl %2,%1\n\tsbbl %0,%0"
		:"=r" (oldbit),ADDR
		:"dIr" (nr) : "memory");
	return oldbit;
}

#if 0 /* Fool kernel-doc since it doesn't do macros yet */
/**
 * test_bit - Determine whether a bit is set
 * @nr: bit number to test
 * @addr: Address to start counting from
 */
static int test_bit(int nr, const volatile void * addr);
#endif

static __inline__ int constant_test_bit(int nr, const volatile void * addr)
{
	return ((1UL << (nr & 31)) & (((const volatile unsigned int *) addr)[nr >> 5])) != 0;
}

static __inline__ int variable_test_bit(int nr, volatile const void * addr)
{
	int oldbit;

	__asm__ __volatile__(
		"btl %2,%1\n\tsbbl %0,%0"
		:"=r" (oldbit)
		:"m" (*(volatile long *)addr),"dIr" (nr));
	return oldbit;
}

#define test_bit(nr,addr) \
(__builtin_constant_p(nr) ? \
 constant_test_bit((nr),(addr)) : \
 variable_test_bit((nr),(addr)))

#undef ADDR

extern long find_first_zero_bit(const unsigned long * addr, unsigned long size);
extern long find_next_zero_bit (const unsigned long * addr, long size, long offset);
extern long find_first_bit(const unsigned long * addr, unsigned long size);
extern long find_next_bit(const unsigned long * addr, long size, long offset);

/* return index of first bet set in val or max when no bit is set */
static inline unsigned long __scanbit(unsigned long val, unsigned long max)
{
	asm("bsfq %1,%0 ; cmovz %2,%0" : "=&r" (val) : "r" (val), "r" (max));
	return val;
}

#define find_first_bit(addr,size) \
((__builtin_constant_p(size) && (size) <= BITS_PER_LONG ? \
  (__scanbit(*(unsigned long *)addr,(size))) : \
  find_first_bit(addr,size)))

#define find_next_bit(addr,size,off) \
((__builtin_constant_p(size) && (size) <= BITS_PER_LONG ? 	  \
  ((off) + (__scanbit((*(unsigned long *)addr) >> (off),(size)-(off)))) : \
	find_next_bit(addr,size,off)))

#define find_first_zero_bit(addr,size) \
((__builtin_constant_p(size) && (size) <= BITS_PER_LONG ? \
  (__scanbit(~*(unsigned long *)addr,(size))) : \
  	find_first_zero_bit(addr,size)))
	
#define find_next_zero_bit(addr,size,off) \
((__builtin_constant_p(size) && (size) <= BITS_PER_LONG ? 	  \
  ((off)+(__scanbit(~(((*(unsigned long *)addr)) >> (off)),(size)-(off)))) : \
	find_next_zero_bit(addr,size,off)))

/* 
 * Find string of zero bits in a bitmap. -1 when not found.
 */ 
extern unsigned long 
find_next_zero_string(unsigned long *bitmap, long start, long nbits, int len);

static inline void set_bit_string(unsigned long *bitmap, unsigned long i, 
				  int len) 
{ 
	unsigned long end = i + len; 
	while (i < end) {
		__set_bit(i, bitmap); 
		i++;
	}
} 

static inline void __clear_bit_string(unsigned long *bitmap, unsigned long i, 
				    int len) 
{ 
	unsigned long end = i + len; 
	while (i < end) {
		__clear_bit(i, bitmap); 
		i++;
	}
} 

/**
 * ffz - find first zero in word.
 * @word: The word to search
 *
 * Undefined if no zero exists, so code should check against ~0UL first.
 */
static __inline__ unsigned long ffz(unsigned long word)
{
	__asm__("bsfq %1,%0"
		:"=r" (word)
		:"r" (~word));
	return word;
}

/**
 * __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)
{
	__asm__("bsfq %1,%0"
		:"=r" (word)
		:"rm" (word));
	return word;
}

/*
 * __fls: find last bit set.
 * @word: The word to search
 *
 * Undefined if no zero exists, so code should check against ~0UL first.
 */
static __inline__ unsigned long __fls(unsigned long word)
{
	__asm__("bsrq %1,%0"
		:"=r" (word)
		:"rm" (word));
	return word;
}

#ifdef __KERNEL__

#include <asm-generic/bitops/sched.h>

/**
 * ffs - find first bit set
 * @x: the word to search
 *
 * This is defined the same way as
 * the libc and compiler builtin ffs routines, therefore
 * differs in spirit from the above ffz (man ffs).
 */
static __inline__ int ffs(int x)
{
	int r;

	__asm__("bsfl %1,%0\n\t"
		"cmovzl %2,%0" 
		: "=r" (r) : "rm" (x), "r" (-1));
	return r+1;
}

/**
 * fls64 - find last bit set in 64 bit word
 * @x: the word to search
 *
 * This is defined the same way as fls.
 */
static __inline__ int fls64(__u64 x)
{
	if (x == 0)
		return 0;
	return __fls(x) + 1;
}

/**
 * fls - find last bit set
 * @x: the word to search
 *
 * This is defined the same way as ffs.
 */
static __inline__ int fls(int x)
{
	int r;

	__asm__("bsrl %1,%0\n\t"
		"cmovzl %2,%0"
		: "=&r" (r) : "rm" (x), "rm" (-1));
	return r+1;
}

#define ARCH_HAS_FAST_MULTIPLIER 1

#include <asm-generic/bitops/hweight.h>

#endif /* __KERNEL__ */

#ifdef __KERNEL__

#include <asm-generic/bitops/ext2-non-atomic.h>

#define ext2_set_bit_atomic(lock,nr,addr) \
	        test_and_set_bit((nr),(unsigned long*)addr)
#define ext2_clear_bit_atomic(lock,nr,addr) \
	        test_and_clear_bit((nr),(unsigned long*)addr)

#include <asm-generic/bitops/minix.h>

#endif /* __KERNEL__ */

#endif /* _X86_64_BITOPS_H */