1 /*
2 * Copyright (C) 2016 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include "ufdt_prop_dict.h"
18
19 #include "libfdt.h"
20
21 #include "libufdt_sysdeps.h"
22
23 #define UFDT_PROP_DICT_INIT_SZ 4
24
25 /* Empirical values for hash functions. */
26 #define HASH_BASE 13131
27
28 #define DICT_LIMIT_NUM 2
29 #define DICT_LIMIT_DEN 3
30
_ufdt_prop_dict_str_hash(const char * str)31 static int _ufdt_prop_dict_str_hash(const char *str) {
32 int res = 0;
33
34 for (; *str != '\0'; str++) {
35 res *= HASH_BASE;
36 res += *str;
37 }
38
39 return res;
40 }
41
_ufdt_prop_dict_find_index_by_name(const struct ufdt_prop_dict * dict,const char * name)42 static const struct fdt_property **_ufdt_prop_dict_find_index_by_name(
43 const struct ufdt_prop_dict *dict, const char *name) {
44 /* size should be 2^k for some k */
45 int hash = _ufdt_prop_dict_str_hash(name);
46 int size = dict->mem_size;
47 int idx = hash & (size - 1);
48 /* If collision, use linear probing to find idx in the hash table */
49 for (int i = 0; i < size; i++) {
50 const struct fdt_property **prop_ptr = &dict->props[idx];
51 const struct fdt_property *prop = *prop_ptr;
52 if (prop == NULL) return prop_ptr;
53
54 const char *prop_name = fdt_string(dict->fdtp, fdt32_to_cpu(prop->nameoff));
55 if (dto_strcmp(prop_name, name) == 0) return prop_ptr;
56
57 idx = (idx + 1) & (size - 1);
58 }
59 return NULL;
60 }
61
_ufdt_prop_dict_find_index(struct ufdt_prop_dict * dict,const struct fdt_property * prop)62 static const struct fdt_property **_ufdt_prop_dict_find_index(
63 struct ufdt_prop_dict *dict, const struct fdt_property *prop) {
64 const char *name = fdt_string(dict->fdtp, fdt32_to_cpu(prop->nameoff));
65
66 return _ufdt_prop_dict_find_index_by_name(dict, name);
67 }
68
_ufdt_prop_dict_construct_int(struct ufdt_prop_dict * dict,void * fdtp,int size)69 int _ufdt_prop_dict_construct_int(struct ufdt_prop_dict *dict, void *fdtp,
70 int size) {
71 const size_t entry_size = sizeof(const struct fdt_property *);
72 const struct fdt_property **props =
73 (const struct fdt_property **)dto_malloc(size * entry_size);
74 if (props == NULL) return -1;
75 dto_memset(props, 0, size * entry_size);
76
77 dict->mem_size = size;
78 dict->num_used = 0;
79 dict->fdtp = fdtp;
80 dict->props = props;
81
82 return 0;
83 }
84
ufdt_prop_dict_construct(struct ufdt_prop_dict * dict,void * fdtp)85 int ufdt_prop_dict_construct(struct ufdt_prop_dict *dict, void *fdtp) {
86 return _ufdt_prop_dict_construct_int(dict, fdtp, UFDT_PROP_DICT_INIT_SZ);
87 }
88
ufdt_prop_dict_destruct(struct ufdt_prop_dict * dict)89 void ufdt_prop_dict_destruct(struct ufdt_prop_dict *dict) {
90 if (dict == NULL) return;
91
92 dto_free(dict->props);
93 }
94
_ufdt_prop_dict_enlarge_if_needed(struct ufdt_prop_dict * dict)95 static int _ufdt_prop_dict_enlarge_if_needed(struct ufdt_prop_dict *dict) {
96 if (dict == NULL) return -1;
97
98 /* Enlarge if the used number over than DICT_LIMIT_NUM / DICT_LIMIT_DEN */
99 if (dict->num_used * DICT_LIMIT_DEN <= dict->mem_size * DICT_LIMIT_NUM) {
100 return 0;
101 }
102
103 int new_size = dict->mem_size * 2;
104 struct ufdt_prop_dict temp_dict;
105 _ufdt_prop_dict_construct_int(&temp_dict, dict->fdtp, new_size);
106
107 for (int i = 0; i < dict->mem_size; i++) {
108 const struct fdt_property *prop = dict->props[i];
109 if (prop == NULL) continue;
110 const struct fdt_property **new_prop_ptr =
111 _ufdt_prop_dict_find_index(&temp_dict, prop);
112 if (new_prop_ptr == NULL) {
113 dto_error("ufdt_prop_dict: failed to find new index when enlarging.\n");
114 ufdt_prop_dict_destruct(&temp_dict);
115 return -1;
116 }
117 *new_prop_ptr = prop;
118 }
119
120 dto_free(dict->props);
121
122 dict->mem_size = new_size;
123 dict->props = temp_dict.props;
124
125 return 0;
126 }
127
ufdt_prop_dict_add(struct ufdt_prop_dict * dict,const struct fdt_property * prop)128 int ufdt_prop_dict_add(struct ufdt_prop_dict *dict,
129 const struct fdt_property *prop) {
130 const struct fdt_property **prop_ptr = _ufdt_prop_dict_find_index(dict, prop);
131 if (prop_ptr == NULL) {
132 dto_error("ufdt_prop_dict: failed to find new index when adding.\n");
133 return -1;
134 }
135
136 if (*prop_ptr == NULL) dict->num_used++;
137 *prop_ptr = prop;
138
139 return _ufdt_prop_dict_enlarge_if_needed(dict);
140 }
141
ufdt_prop_dict_find(const struct ufdt_prop_dict * dict,const char * name)142 const struct fdt_property *ufdt_prop_dict_find(const struct ufdt_prop_dict *dict,
143 const char *name) {
144 const struct fdt_property **prop_ptr =
145 _ufdt_prop_dict_find_index_by_name(dict, name);
146 return prop_ptr ? *prop_ptr : NULL;
147 }
148