linux/include/asm-generic/atomic.h

#ifndef _ASM_GENERIC_ATOMIC_H
#define _ASM_GENERIC_ATOMIC_H
/*
 * Copyright (C) 2005 Silicon Graphics, Inc.
 *	Christoph Lameter <clameter@sgi.com>
 *
 * Allows to provide arch independent atomic definitions without the need to
 * edit all arch specific atomic.h files.
 */

#include <asm/types.h>

/*
 * Suppport for atomic_long_t
 *
 * Casts for parameters are avoided for existing atomic functions in order to
 * avoid issues with cast-as-lval under gcc 4.x and other limitations that the
 * macros of a platform may have.
 */

#if BITS_PER_LONG == 64

typedef atomic64_t atomic_long_t;

#define ATOMIC_LONG_INIT(i)	ATOMIC64_INIT(i)

static inline long atomic_long_read(atomic_long_t *l)
{
	atomic64_t *v = (atomic64_t *)l;

	return (long)atomic64_read(v);
}

static inline void atomic_long_set(atomic_long_t *l, long i)
{
	atomic64_t *v = (atomic64_t *)l;

	atomic64_set(v, i);
}

static inline void atomic_long_inc(atomic_long_t *l)
{
	atomic64_t *v = (atomic64_t *)l;

	atomic64_inc(v);
}

static inline void atomic_long_dec(atomic_long_t *l)
{
	atomic64_t *v = (atomic64_t *)l;

	atomic64_dec(v);
}

static inline void atomic_long_add(long i, atomic_long_t *l)
{
	atomic64_t *v = (atomic64_t *)l;

	atomic64_add(i, v);
}

static inline void atomic_long_sub(long i, atomic_long_t *l)
{
	atomic64_t *v = (atomic64_t *)l;

	atomic64_sub(i, v);
}

#else

typedef atomic_t atomic_long_t;

#define ATOMIC_LONG_INIT(i)	ATOMIC_INIT(i)
static inline long atomic_long_read(atomic_long_t *l)
{
	atomic_t *v = (atomic_t *)l;

	return (long)atomic_read(v);
}

static inline void atomic_long_set(atomic_long_t *l, long i)
{
	atomic_t *v = (atomic_t *)l;

	atomic_set(v, i);
}

static inline void atomic_long_inc(atomic_long_t *l)
{
	atomic_t *v = (atomic_t *)l;

	atomic_inc(v);
}

static inline void atomic_long_dec(atomic_long_t *l)
{
	atomic_t *v = (atomic_t *)l;

	atomic_dec(v);
}

static inline void atomic_long_add(long i, atomic_long_t *l)
{
	atomic_t *v = (atomic_t *)l;

	atomic_add(i, v);
}

static inline void atomic_long_sub(long i, atomic_long_t *l)
{
	atomic_t *v = (atomic_t *)l;

	atomic_sub(i, v);
}

#endif
#endif