sync_bitops.h

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#ifndef _ASM_X86_SYNC_BITOPS_H
#define _ASM_X86_SYNC_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).
 */

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

static inline void sync_set_bit(int nr, volatile unsigned long *addr)
{
    asm volatile("lock; btsl %1,%0"
             : "+m" (ADDR)
             : "Ir" (nr)
             : "memory");
}

static inline void sync_clear_bit(int nr, volatile unsigned long *addr)
{
    asm volatile("lock; btrl %1,%0"
             : "+m" (ADDR)
             : "Ir" (nr)
             : "memory");
}

static inline void sync_change_bit(int nr, volatile unsigned long *addr)
{
    asm volatile("lock; btcl %1,%0"
             : "+m" (ADDR)
             : "Ir" (nr)
             : "memory");
}

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

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

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

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

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

    asm volatile("lock; btcl %2,%1\n\tsbbl %0,%0"
             : "=r" (oldbit), "+m" (ADDR)
             : "Ir" (nr) : "memory");
    return oldbit;
}

#define sync_test_bit(nr, addr) test_bit(nr, addr)

#undef ADDR

#endif /* _ASM_X86_SYNC_BITOPS_H */