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atomic.h

/*
 *  linux/include/asm-arm/atomic.h
 *
 *  Copyright (c) 1996 Russell King.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 *  Changelog:
 *   27-06-1996   RMK   Created
 *   13-04-1997   RMK   Made functions atomic!
 *   07-12-1997   RMK   Upgraded for v2.1.
 *   26-08-1998   PJB   Added #ifdef __KERNEL__
 */
#ifndef __ASM_ARM_ATOMIC_H
#define __ASM_ARM_ATOMIC_H

#include <linux/config.h>

#ifdef CONFIG_SMP
#error SMP not supported
#endif

typedef struct { volatile int counter; } atomic_t;

#define ATOMIC_INIT(i)  { (i) }

#ifdef __KERNEL__
#include <asm/proc/system.h>

#define atomic_read(v)  ((v)->counter)
#define atomic_set(v,i) (((v)->counter) = (i))

static inline void atomic_add(int i, volatile atomic_t *v)
{
      unsigned long flags;

      local_irq_save(flags);
      v->counter += i;
      local_irq_restore(flags);
}

static inline void atomic_sub(int i, volatile atomic_t *v)
{
      unsigned long flags;

      local_irq_save(flags);
      v->counter -= i;
      local_irq_restore(flags);
}

static inline void atomic_inc(volatile atomic_t *v)
{
      unsigned long flags;

      local_irq_save(flags);
      v->counter += 1;
      local_irq_restore(flags);
}

static inline void atomic_dec(volatile atomic_t *v)
{
      unsigned long flags;

      local_irq_save(flags);
      v->counter -= 1;
      local_irq_restore(flags);
}

static inline int atomic_dec_and_test(volatile atomic_t *v)
{
      unsigned long flags;
      int val;

      local_irq_save(flags);
      val = v->counter;
      v->counter = val -= 1;
      local_irq_restore(flags);

      return val == 0;
}

static inline int atomic_add_negative(int i, volatile atomic_t *v)
{
      unsigned long flags;
      int val;

      local_irq_save(flags);
      val = v->counter;
      v->counter = val += i;
      local_irq_restore(flags);

      return val < 0;
}

static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr)
{
      unsigned long flags;

      local_irq_save(flags);
      *addr &= ~mask;
      local_irq_restore(flags);
}

/* Atomic operations are already serializing on ARM */
#define smp_mb__before_atomic_dec() barrier()
#define smp_mb__after_atomic_dec()  barrier()
#define smp_mb__before_atomic_inc() barrier()
#define smp_mb__after_atomic_inc()  barrier()

#endif
#endif

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