linux/include/asm-x86/bitops_32.h

#ifndef _I386_BITOPS_H
#define _I386_BITOPS_H

/*
 * Copyright 1992, Linus Torvalds.
 */

#ifndef _LINUX_BITOPS_H
#error only <linux/bitops.h> can be included directly
#endif

#include <linux/compiler.h>
#include <asm/alternative.h>

/*
 * These have to be done with inline assembly: that way the bit-setting
 * is guaranteed to be atomic. All bit operations return 0 if the bit
 * was cleared before the operation and != 0 if it was not.
 *
 * bit 0 is the LSB of addr; bit 32 is the LSB of (addr+1).
 */

#define ADDR (*(volatile long *) addr)

/**
 * 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: there are no guarantees that this function will not be reordered
 * on non x86 architectures, so if you are writing portable code,
 * make sure not to rely on its reordering 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 unsigned long *addr)
{
	__asm__ __volatile__( LOCK_PREFIX
		"btsl %1,%0"
		:"+m" (ADDR)
		:"Ir" (nr));
}

/**
 * __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)
{
	__asm__(
		"btsl %1,%0"
		:"+m" (ADDR)
		:"Ir" (nr));
}

/**
 * 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 unsigned long *addr)
{
	__asm__ __volatile__( LOCK_PREFIX
		"btrl %1,%0"
		:"+m" (ADDR)
		:"Ir" (nr));
}

/*
 * clear_bit_unlock - Clears a bit in memory
 * @nr: Bit to clear
 * @addr: Address to start counting from
 *
 * clear_bit() is atomic and implies release semantics before the memory
 * operation. It can be used for an unlock.
 */
static inline void clear_bit_unlock(unsigned long nr, volatile unsigned long *addr)
{
	barrier();
	clear_bit(nr, addr);
}

static inline void __clear_bit(int nr, volatile unsigned long *addr)
{
	__asm__ __volatile__(
		"btrl %1,%0"
		:"+m" (ADDR)
		:"Ir" (nr));
}

/*
 * __clear_bit_unlock - Clears a bit in memory
 * @nr: Bit to clear
 * @addr: Address to start counting from
 *
 * __clear_bit() is non-atomic and implies release semantics before the memory
 * operation. It can be used for an unlock if no other CPUs can concurrently
 * modify other bits in the word.
 *
 * No memory barrier is required here, because x86 cannot reorder stores past
 * older loads. Same principle as spin_unlock.
 */
static inline void __clear_bit_unlock(unsigned long nr, volatile unsigned long *addr)
{
	barrier();
	__clear_bit(nr, addr);
}

#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 unsigned long *addr)
{
	__asm__ __volatile__(
		"btcl %1,%0"
		:"+m" (ADDR)
		:"Ir" (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. It may be
 * reordered on other architectures than x86.
 * 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 unsigned long *addr)
{
	__asm__ __volatile__( LOCK_PREFIX
		"btcl %1,%0"
		:"+m" (ADDR)
		:"Ir" (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 may be reordered on other architectures than x86.
 * It also implies a memory barrier.
 */
static inline int test_and_set_bit(int nr, volatile unsigned long *addr)
{
	int oldbit;

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

/**
 * test_and_set_bit_lock - Set a bit and return its old value for lock
 * @nr: Bit to set
 * @addr: Address to count from
 *
 * This is the same as test_and_set_bit on x86.
 */
static inline int test_and_set_bit_lock(int nr, volatile unsigned long *addr)
{
	return test_and_set_bit(nr, addr);
}

/**
 * __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)
{
	int oldbit;

	__asm__(
		"btsl %2,%1\n\tsbbl %0,%0"
		:"=r" (oldbit),"+m" (ADDR)
		:"Ir" (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 can be reorderdered on other architectures other than x86.
 * It also implies a memory barrier.
 */
static inline int test_and_clear_bit(int nr, volatile unsigned long *addr)
{
	int oldbit;

	__asm__ __volatile__( LOCK_PREFIX
		"btrl %2,%1\n\tsbbl %0,%0"
		:"=r" (oldbit),"+m" (ADDR)
		:"Ir" (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 unsigned long *addr)
{
	int oldbit;

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

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

	__asm__ __volatile__(
		"btcl %2,%1\n\tsbbl %0,%0"
		:"=r" (oldbit),"+m" (ADDR)
		:"Ir" (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 unsigned long *addr)
{
	int oldbit;

	__asm__ __volatile__( LOCK_PREFIX
		"btcl %2,%1\n\tsbbl %0,%0"
		:"=r" (oldbit),"+m" (ADDR)
		:"Ir" (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 __always_inline int constant_test_bit(int nr, const volatile unsigned long *addr)
{
	return ((1UL << (nr & 31)) & (addr[nr >> 5])) != 0;
}

static inline int variable_test_bit(int nr, const volatile unsigned long *addr)
{
	int oldbit;

	__asm__ __volatile__(
		"btl %2,%1\n\tsbbl %0,%0"
		:"=r" (oldbit)
		:"m" (ADDR),"Ir" (nr));
	return oldbit;
}

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

#undef ADDR

/**
 * find_first_zero_bit - find the first zero bit in a memory region
 * @addr: The address to start the search at
 * @size: The maximum size to search
 *
 * Returns the bit number of the first zero bit, not the number of the byte
 * containing a bit.
 */
static inline int find_first_zero_bit(const unsigned long *addr, unsigned size)
{
	int d0, d1, d2;
	int res;

	if (!size)
		return 0;
	/* This looks at memory. Mark it volatile to tell gcc not to move it around */
	__asm__ __volatile__(
		"movl $-1,%%eax\n\t"
		"xorl %%edx,%%edx\n\t"
		"repe; scasl\n\t"
		"je 1f\n\t"
		"xorl -4(%%edi),%%eax\n\t"
		"subl $4,%%edi\n\t"
		"bsfl %%eax,%%edx\n"
		"1:\tsubl %%ebx,%%edi\n\t"
		"shll $3,%%edi\n\t"
		"addl %%edi,%%edx"
		:"=d" (res), "=&c" (d0), "=&D" (d1), "=&a" (d2)
		:"1" ((size + 31) >> 5), "2" (addr), "b" (addr) : "memory");
	return res;
}

/**
 * find_next_zero_bit - find the first zero bit in a memory region
 * @addr: The address to base the search on
 * @offset: The bit number to start searching at
 * @size: The maximum size to search
 */
int find_next_zero_bit(const unsigned long *addr, int size, int offset);

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

/**
 * find_first_bit - find the first set bit in a memory region
 * @addr: The address to start the search at
 * @size: The maximum size to search
 *
 * Returns the bit number of the first set bit, not the number of the byte
 * containing a bit.
 */
static inline unsigned find_first_bit(const unsigned long *addr, unsigned size)
{
	unsigned x = 0;

	while (x < size) {
		unsigned long val = *addr++;
		if (val)
			return __ffs(val) + x;
		x += (sizeof(*addr)<<3);
	}
	return x;
}

/**
 * find_next_bit - find the first set bit in a memory region
 * @addr: The address to base the search on
 * @offset: The bit number to start searching at
 * @size: The maximum size to search
 */
int find_next_bit(const unsigned long *addr, int size, int offset);

/**
 * 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__("bsfl %1,%0"
		:"=r" (word)
		:"r" (~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"
		"jnz 1f\n\t"
		"movl $-1,%0\n"
		"1:" : "=r" (r) : "rm" (x));
	return r+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"
		"jnz 1f\n\t"
		"movl $-1,%0\n"
		"1:" : "=r" (r) : "rm" (x));
	return r+1;
}

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

#endif /* __KERNEL__ */

#include <asm-generic/bitops/fls64.h>

#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 /* _I386_BITOPS_H */