[lttng-modules.git] / lib / align.h

#ifndef _LTTNG_ALIGN_H
#define _LTTNG_ALIGN_H

/*
 * lib/align.h
 *
 * Copyright (C) 2010-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; only
 * version 2.1 of the License.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#ifdef __KERNEL__

#include <linux/types.h>
#include <lib/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
Commit	Line	Data
	1	#ifndef _LTTNG_ALIGN_H
	2	#define _LTTNG_ALIGN_H
	3
	4	/*
	5	* lib/align.h
	6	*
	7	* Copyright (C) 2010-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	8	*
	9	* This library is free software; you can redistribute it and/or
	10	* modify it under the terms of the GNU Lesser General Public
	11	* License as published by the Free Software Foundation; only
	12	* version 2.1 of the License.
	13	*
	14	* This library is distributed in the hope that it will be useful,
	15	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	16	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	17	* Lesser General Public License for more details.
	18	*
	19	* You should have received a copy of the GNU Lesser General Public
	20	* License along with this library; if not, write to the Free Software
	21	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
	22	*/
	23
	24	#ifdef __KERNEL__
	25
	26	#include <linux/types.h>
	27	#include <lib/bug.h>
	28
	29	#define ALIGN_FLOOR(x, a) __ALIGN_FLOOR_MASK(x, (typeof(x)) (a) - 1)
	30	#define __ALIGN_FLOOR_MASK(x, mask) ((x) & ~(mask))
	31	#define PTR_ALIGN_FLOOR(p, a) \
	32	((typeof(p)) ALIGN_FLOOR((unsigned long) (p), a))
	33
	34	/*
	35	* Align pointer on natural object alignment.
	36	*/
	37	#define object_align(obj) PTR_ALIGN(obj, __alignof__(*(obj)))
	38	#define object_align_floor(obj) PTR_ALIGN_FLOOR(obj, __alignof__(*(obj)))
	39
	40	/**
	41	* offset_align - Calculate the offset needed to align an object on its natural
	42	* alignment towards higher addresses.
	43	* @align_drift: object offset from an "alignment"-aligned address.
	44	* @alignment: natural object alignment. Must be non-zero, power of 2.
	45	*
	46	* Returns the offset that must be added to align towards higher
	47	* addresses.
	48	*/
	49	#define offset_align(align_drift, alignment) \
	50	({ \
	51	BUILD_RUNTIME_BUG_ON((alignment) == 0 \
	52	\|\| ((alignment) & ((alignment) - 1))); \
	53	(((alignment) - (align_drift)) & ((alignment) - 1)); \
	54	})
	55
	56	/**
	57	* offset_align_floor - Calculate the offset needed to align an object
	58	* on its natural alignment towards lower addresses.
	59	* @align_drift: object offset from an "alignment"-aligned address.
	60	* @alignment: natural object alignment. Must be non-zero, power of 2.
	61	*
	62	* Returns the offset that must be substracted to align towards lower addresses.
	63	*/
	64	#define offset_align_floor(align_drift, alignment) \
	65	({ \
	66	BUILD_RUNTIME_BUG_ON((alignment) == 0 \
	67	\|\| ((alignment) & ((alignment) - 1))); \
	68	(((align_drift) - (alignment)) & ((alignment) - 1)); \
	69	})
	70
	71	#endif /* __KERNEL__ */
	72
	73	#endif