bitops.c

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/*
 * bitops.c: atomic operations which got too long to be inlined all over
 *      the place.
 * 
 * Copyright 1999 Philipp Rumpf ([email protected])
 * Copyright 2000 Grant Grundler ([email protected])
 */

#include <linux/kernel.h>
#include <linux/spinlock.h>
#include <linux/atomic.h>

#ifdef CONFIG_SMP
arch_spinlock_t __atomic_hash[ATOMIC_HASH_SIZE] __lock_aligned = {
    [0 ... (ATOMIC_HASH_SIZE-1)]  = __ARCH_SPIN_LOCK_UNLOCKED
};
#endif

#ifdef CONFIG_64BIT
unsigned long __xchg64(unsigned long x, unsigned long *ptr)
{
    unsigned long temp, flags;

    _atomic_spin_lock_irqsave(ptr, flags);
    temp = *ptr;
    *ptr = x;
    _atomic_spin_unlock_irqrestore(ptr, flags);
    return temp;
}
#endif

unsigned long __xchg32(int x, int *ptr)
{
    unsigned long flags;
    long temp;

    _atomic_spin_lock_irqsave(ptr, flags);
    temp = (long) *ptr; /* XXX - sign extension wanted? */
    *ptr = x;
    _atomic_spin_unlock_irqrestore(ptr, flags);
    return (unsigned long)temp;
}


unsigned long __xchg8(char x, char *ptr)
{
    unsigned long flags;
    long temp;

    _atomic_spin_lock_irqsave(ptr, flags);
    temp = (long) *ptr; /* XXX - sign extension wanted? */
    *ptr = x;
    _atomic_spin_unlock_irqrestore(ptr, flags);
    return (unsigned long)temp;
}


#ifdef CONFIG_64BIT
unsigned long __cmpxchg_u64(volatile unsigned long *ptr, unsigned long old, unsigned long new)
{
    unsigned long flags;
    unsigned long prev;

    _atomic_spin_lock_irqsave(ptr, flags);
    if ((prev = *ptr) == old)
        *ptr = new;
    _atomic_spin_unlock_irqrestore(ptr, flags);
    return prev;
}
#endif

unsigned long __cmpxchg_u32(volatile unsigned int *ptr, unsigned int old, unsigned int new)
{
    unsigned long flags;
    unsigned int prev;

    _atomic_spin_lock_irqsave(ptr, flags);
    if ((prev = *ptr) == old)
        *ptr = new;
    _atomic_spin_unlock_irqrestore(ptr, flags);
    return (unsigned long)prev;
}