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/*

 * include/linux/id.h

 *

 * 2002-10-18  written by Jim Houston jim.houston@ccur.com

 *      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.

 */

#include <linux/types.h>

#include <asm/bitops.h>

#define RESERVED_ID_BITS 8

#if BITS_PER_LONG == 32

# define IDR_BITS 5

# define IDR_FULL 0xffffffff

#elif BITS_PER_LONG == 64

# define IDR_BITS 6

# define IDR_FULL 0xffffffffffffffff

#else

# error "BITS_PER_LONG is not 32 or 64"

#endif

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

/* Define the size of the id's */

#define BITS_PER_INT (sizeof(int)*8)

#define MAX_ID_SHIFT (BITS_PER_INT - RESERVED_ID_BITS)

#define MAX_ID_BIT (1 << 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;

        long              count;

        int               layers;

        int               id_free_cnt;

        spinlock_t        lock;

};

/*

 * This is what we export.

 */

void *idr_find(struct idr *idp, int id);

int idr_pre_get(struct idr *idp);

int idr_get_new(struct idr *idp, void *ptr);

void idr_remove(struct idr *idp, int id);

void idr_init(struct idr *idp);

extern kmem_cache_t *idr_layer_cache;