lttng: offset alignment header

#ifndef _LTTNG_ALIGN_H

#define _LTTNG_ALIGN_H

/*

 * lib/align.h

 *

 * (C) Copyright 2010-2011 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

 *

 * Dual LGPL v2.1/GPL v2 license.

 */

#ifdef __KERNEL__

#include <linux/types.h>

#include "bug.h"

#define ALIGN_FLOOR(x, a)	__ALIGN_FLOOR_MASK(x, (typeof(x)) (a) - 1)

#define __ALIGN_FLOOR_MASK(x, mask)	((x) & ~(mask))

#define PTR_ALIGN_FLOOR(p, a) \

			((typeof(p)) ALIGN_FLOOR((unsigned long) (p), a))

/*

 * Align pointer on natural object alignment.

 */

#define object_align(obj)	PTR_ALIGN(obj, __alignof__(*(obj)))

#define object_align_floor(obj)	PTR_ALIGN_FLOOR(obj, __alignof__(*(obj)))

/**

 * offset_align - Calculate the offset needed to align an object on its natural

 *                alignment towards higher addresses.

 * @align_drift:  object offset from an "alignment"-aligned address.

 * @alignment:    natural object alignment. Must be non-zero, power of 2.

 *

 * Returns the offset that must be added to align towards higher

 * addresses.

 */

#define offset_align(align_drift, alignment)				       \

	({								       \

		BUILD_RUNTIME_BUG_ON((alignment) == 0			       \

				   || ((alignment) & ((alignment) - 1)));      \

		(((alignment) - (align_drift)) & ((alignment) - 1));	       \

	})

/**

 * offset_align_floor - Calculate the offset needed to align an object

 *                      on its natural alignment towards lower addresses.

 * @align_drift:  object offset from an "alignment"-aligned address.

 * @alignment:    natural object alignment. Must be non-zero, power of 2.

 *

 * Returns the offset that must be substracted to align towards lower addresses.

 */

#define offset_align_floor(align_drift, alignment)			       \

	({								       \

		BUILD_RUNTIME_BUG_ON((alignment) == 0			       \

				   || ((alignment) & ((alignment) - 1)));      \

		(((align_drift) - (alignment)) & ((alignment) - 1);	       \

	})

#endif /* __KERNEL__ */

#endif