2 * Copyright (c) 2011 Intel Corporation. All rights reserved.
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37 #include <sys/types.h>
43 * Indexer - to find a structure given an index
45 * We store pointers using a double lookup and return an index to the
46 * user which is then used to retrieve the pointer. The upper bits of
47 * the index are itself an index into an array of memory allocations.
48 * The lower bits specify the offset into the allocated memory where
49 * the pointer is stored.
51 * This allows us to adjust the number of pointers stored by the index
52 * list without taking a lock during data lookups.
55 static int idx_grow(struct indexer *idx)
57 union idx_entry *entry;
60 if (idx->size >= IDX_ARRAY_SIZE)
63 idx->array[idx->size] = calloc(IDX_ENTRY_SIZE, sizeof(union idx_entry));
64 if (!idx->array[idx->size])
67 entry = idx->array[idx->size];
68 start_index = idx->size << IDX_ENTRY_BITS;
69 entry[IDX_ENTRY_SIZE - 1].next = idx->free_list;
71 for (i = IDX_ENTRY_SIZE - 2; i >= 0; i--)
72 entry[i].next = start_index + i + 1;
74 /* Index 0 is reserved */
77 idx->free_list = start_index;
86 int idx_insert(struct indexer *idx, void *item)
88 union idx_entry *entry;
91 if ((index = idx->free_list) == 0) {
92 if ((index = idx_grow(idx)) <= 0)
96 entry = idx->array[idx_array_index(index)];
97 idx->free_list = entry[idx_entry_index(index)].next;
98 entry[idx_entry_index(index)].item = item;
102 void *idx_remove(struct indexer *idx, int index)
104 union idx_entry *entry;
107 entry = idx->array[idx_array_index(index)];
108 item = entry[idx_entry_index(index)].item;
109 entry[idx_entry_index(index)].next = idx->free_list;
110 idx->free_list = index;
114 void idx_replace(struct indexer *idx, int index, void *item)
116 union idx_entry *entry;
118 entry = idx->array[idx_array_index(index)];
119 entry[idx_entry_index(index)].item = item;
123 static int idm_grow(struct index_map *idm, int index)
125 idm->array[idx_array_index(index)] = calloc(IDX_ENTRY_SIZE, sizeof(void *));
126 if (!idm->array[idx_array_index(index)])
136 int idm_set(struct index_map *idm, int index, void *item)
140 if (index > IDX_MAX_INDEX) {
145 if (!idm->array[idx_array_index(index)]) {
146 if (idm_grow(idm, index) < 0)
150 entry = idm->array[idx_array_index(index)];
151 entry[idx_entry_index(index)] = item;
155 void *idm_clear(struct index_map *idm, int index)
160 entry = idm->array[idx_array_index(index)];
161 item = entry[idx_entry_index(index)];
162 entry[idx_entry_index(index)] = NULL;