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