4 * 2002-10-18 written by Jim Houston jim.houston@ccur.com
5 * Copyright (C) 2002 by Concurrent Computer Corporation
6 * Distributed under the GNU GPL license version 2.
8 * Small id to pointer translation service avoiding fixed sized
15 #include <linux/types.h>
16 #include <linux/bitops.h>
18 #if BITS_PER_LONG == 32
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
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)
33 # error "BITS_PER_LONG is not 32 or 64"
36 #define IDR_SIZE (1 << IDR_BITS)
37 #define IDR_MASK ((1 << IDR_BITS)-1)
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)
43 /* Leave the possibility of an incomplete final layer */
44 #define MAX_LEVEL (MAX_ID_SHIFT + IDR_BITS - 1) / IDR_BITS
46 /* Number of id_layer structs to leave in free list */
47 #define IDR_FREE_MAX MAX_LEVEL + MAX_LEVEL
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 */
56 struct idr_layer
*top
;
57 struct idr_layer
*id_free
;
63 #define IDR_INIT(name) \
69 .lock = __SPIN_LOCK_UNLOCKED(name.lock), \
71 #define DEFINE_IDR(name) struct idr name = IDR_INIT(name)
74 * This is what we export.
77 void *idr_find(struct idr
*idp
, int id
);
78 int idr_pre_get(struct idr
*idp
, gfp_t gfp_mask
);
79 int idr_get_new(struct idr
*idp
, void *ptr
, int *id
);
80 int idr_get_new_above(struct idr
*idp
, void *ptr
, int starting_id
, int *id
);
81 void *idr_replace(struct idr
*idp
, void *ptr
, int id
);
82 void idr_remove(struct idr
*idp
, int id
);
83 void idr_destroy(struct idr
*idp
);
84 void idr_init(struct idr
*idp
);
86 #endif /* __IDR_H__ */
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