text: #ifndef _I386_BITOPS_H
  #define _I386_BITOPS_H
  
  /*
   * Copyright 1992, Linus Torvalds.
   */
  
  
  /*
   * 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).
   */
  
  #ifdef CONFIG_SMP
  #define LOCK_PREFIX "lock ; "
  #else
  #define LOCK_PREFIX ""
  #endif
  
  #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 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"
  		:"=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 void * 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 void * addr)
  {
  	__asm__ __volatile__( LOCK_PREFIX
  		"btrl %1,%0"
  		:"=m" (ADDR)
  		:"Ir" (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 set
   * @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"
  		:"=m" (ADDR)
  		:"Ir" (nr));
  }
  
  /**
   * change_bit - Toggle a bit in memory
   * @nr: Bit to clear
   * @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"
  		:"=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 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),"=m" (ADDR)
  		:"Ir" (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),"=m" (ADDR)
  		:"Ir" (nr));
  	return oldbit;
  }
  
  /**
   * test_and_clear_bit - Clear 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_clear_bit(int nr, volatile void * 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 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_clear_bit(int nr, volatile void * 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 void * 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 new 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_change_bit(int nr, volatile void * 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 __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 void * 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)))
  
  /**
   * 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(void * 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));
  	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 bitnumber to start searching at
   * @size: The maximum size to search
   */
  static __inline__ int find_next_zero_bit (void * addr, int size, int offset)
  {
  	unsigned long * p = ((unsigned long *) addr) + (offset >> 5);
  	int set = 0, bit = offset & 31, res;
  
  	if (bit) {
  		/*
  		 * Look for zero in first byte
  		 */
  		__asm__("bsfl %1,%0\n\t"
  			"jne 1f\n\t"
  			"movl $32, %0\n"
  			"1:"
  			: "=r" (set)
  			: "r" (~(*p >> bit)));
  		if (set < (32 - bit))
  			return set + offset;
  		set = 32 - bit;
  		p++;
  	}
  	/*
  	 * No zero yet, search remaining full bytes for a zero
  	 */
  	res = find_first_zero_bit (p, size - 32 * (p - (unsigned long *) addr));
  	return (offset + set + res);
  }
  
  /**
   * 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__
  
  /**
   * 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) : "g" (x));
  	return r+1;
  }
  
  /**
   * hweightN - returns the hamming weight of a N-bit word
   * @x: the word to weigh
   *
   * The Hamming Weight of a number is the total number of bits set in it.
   */
  
  #define hweight32(x) generic_hweight32(x)
  #define hweight16(x) generic_hweight16(x)
  #define hweight8(x) generic_hweight8(x)
  
  #endif /* __KERNEL__ */
  
  #ifdef __KERNEL__
  
  #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 /* _I386_BITOPS_H */
  