[linux.git] / include / linux / idr.h

/*
 * include/linux/idr.h
 * 
 * 2002-10-18  written by Jim Houston [email protected]
 *	Copyright (C) 2002 by Concurrent Computer Corporation
 *	Distributed under the GNU GPL license version 2.
 *
 * Small id to pointer translation service avoiding fixed sized
 * tables.
 */

#ifndef __IDR_H__
#define __IDR_H__

#include <linux/types.h>
#include <linux/bitops.h>

#if BITS_PER_LONG == 32
# define IDR_BITS 5
# define IDR_FULL 0xfffffffful
/* We can only use two of the bits in the top level because there is
   only one possible bit in the top level (5 bits * 7 levels = 35
   bits, but you only use 31 bits in the id). */
# define TOP_LEVEL_FULL (IDR_FULL >> 30)
#elif BITS_PER_LONG == 64
# define IDR_BITS 6
# define IDR_FULL 0xfffffffffffffffful
/* We can only use two of the bits in the top level because there is
   only one possible bit in the top level (6 bits * 6 levels = 36
   bits, but you only use 31 bits in the id). */
# define TOP_LEVEL_FULL (IDR_FULL >> 62)
#else
# error "BITS_PER_LONG is not 32 or 64"
#endif

#define IDR_SIZE (1 << IDR_BITS)
#define IDR_MASK ((1 << IDR_BITS)-1)

#define MAX_ID_SHIFT (sizeof(int)*8 - 1)
#define MAX_ID_BIT (1U << MAX_ID_SHIFT)
#define MAX_ID_MASK (MAX_ID_BIT - 1)

/* Leave the possibility of an incomplete final layer */
#define MAX_LEVEL (MAX_ID_SHIFT + IDR_BITS - 1) / IDR_BITS

/* Number of id_layer structs to leave in free list */
#define IDR_FREE_MAX MAX_LEVEL + MAX_LEVEL

struct idr_layer {
	unsigned long		 bitmap; /* A zero bit means "space here" */
	struct idr_layer	*ary[1<<IDR_BITS];
	int			 count;	 /* When zero, we can release it */
};

struct idr {
	struct idr_layer *top;
	struct idr_layer *id_free;
	int		  layers;
	int		  id_free_cnt;
	spinlock_t	  lock;
};

#define IDR_INIT(name)						\
{								\
	.top		= NULL,					\
	.id_free	= NULL,					\
	.layers 	= 0,					\
	.id_free_cnt	= 0,					\
	.lock		= __SPIN_LOCK_UNLOCKED(name.lock),	\
}
#define DEFINE_IDR(name)	struct idr name = IDR_INIT(name)

/*
 * This is what we export.
 */

void *idr_find(struct idr *idp, int id);
int idr_pre_get(struct idr *idp, gfp_t gfp_mask);
int idr_get_new(struct idr *idp, void *ptr, int *id);
int idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id);
void *idr_replace(struct idr *idp, void *ptr, int id);
void idr_remove(struct idr *idp, int id);
void idr_destroy(struct idr *idp);
void idr_init(struct idr *idp);

#endif /* __IDR_H__ */
Commit	Line	Data
1da177e4 LT	1	/*
	2	* include/linux/idr.h
	3	*
	4	* 2002-10-18 written by Jim Houston [email protected]
	5	* Copyright (C) 2002 by Concurrent Computer Corporation
	6	* Distributed under the GNU GPL license version 2.
	7	*
	8	* Small id to pointer translation service avoiding fixed sized
	9	* tables.
	10	*/
f668ab1a LT	11
	12	#ifndef __IDR_H__
	13	#define __IDR_H__
	14
1da177e4 LT	15	#include <linux/types.h>
	16	#include <linux/bitops.h>
	17
	18	#if BITS_PER_LONG == 32
	19	# define IDR_BITS 5
	20	# define IDR_FULL 0xfffffffful
	21	/* We can only use two of the bits in the top level because there is
	22	only one possible bit in the top level (5 bits * 7 levels = 35
	23	bits, but you only use 31 bits in the id). */
	24	# define TOP_LEVEL_FULL (IDR_FULL >> 30)
	25	#elif BITS_PER_LONG == 64
	26	# define IDR_BITS 6
	27	# define IDR_FULL 0xfffffffffffffffful
	28	/* We can only use two of the bits in the top level because there is
	29	only one possible bit in the top level (6 bits * 6 levels = 36
	30	bits, but you only use 31 bits in the id). */
	31	# define TOP_LEVEL_FULL (IDR_FULL >> 62)
	32	#else
	33	# error "BITS_PER_LONG is not 32 or 64"
	34	#endif
	35
	36	#define IDR_SIZE (1 << IDR_BITS)
	37	#define IDR_MASK ((1 << IDR_BITS)-1)
	38
	39	#define MAX_ID_SHIFT (sizeof(int)*8 - 1)
	40	#define MAX_ID_BIT (1U << MAX_ID_SHIFT)
	41	#define MAX_ID_MASK (MAX_ID_BIT - 1)
	42
	43	/* Leave the possibility of an incomplete final layer */
	44	#define MAX_LEVEL (MAX_ID_SHIFT + IDR_BITS - 1) / IDR_BITS
	45
	46	/* Number of id_layer structs to leave in free list */
	47	#define IDR_FREE_MAX MAX_LEVEL + MAX_LEVEL
	48
	49	struct idr_layer {
	50	unsigned long bitmap; /* A zero bit means "space here" */
	51	struct idr_layer *ary[1<<IDR_BITS];
	52	int count; /* When zero, we can release it */
	53	};
	54
	55	struct idr {
	56	struct idr_layer *top;
	57	struct idr_layer *id_free;
	58	int layers;
	59	int id_free_cnt;
	60	spinlock_t lock;
	61	};
	62
	63	#define IDR_INIT(name) \
	64	{ \
	65	.top = NULL, \
	66	.id_free = NULL, \
	67	.layers = 0, \
	68	.id_free_cnt = 0, \
e4d91918	69	.lock = __SPIN_LOCK_UNLOCKED(name.lock), \
1da177e4 LT	70	}
	71	#define DEFINE_IDR(name) struct idr name = IDR_INIT(name)
	72
	73	/*
	74	* This is what we export.
	75	*/
	76
	77	void idr_find(struct idr idp, int id);
fd4f2df2	78	int idr_pre_get(struct idr *idp, gfp_t gfp_mask);
1da177e4 LT	79	int idr_get_new(struct idr idp, void ptr, int *id);
1da177e4 LT	80	int idr_get_new_above(struct idr idp, void ptr, int starting_id, int *id);
5806f07c	81	void idr_replace(struct idr idp, void *ptr, int id);
1da177e4	82	void idr_remove(struct idr *idp, int id);
8d3b3591	83	void idr_destroy(struct idr *idp);
1da177e4	84	void idr_init(struct idr *idp);
f668ab1a LT	85
f668ab1a LT	86	#endif /* __IDR_H__ */