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/*
* include/linux/idr.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 <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, \
}
#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, unsigned 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_remove(struct idr *idp, int id);
void idr_init(struct idr *idp);
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