source: UsbWattMeter/trunk/curl-7.47.1/lib/splay.c@ 164

Last change on this file since 164 was 164, checked in by coas-nagasima, 6 years ago

TOPPERS/ECNLサンプルアプリ「USB充電器電力計」を追加

  • Property svn:eol-style set to native
  • Property svn:keywords set to Id
  • Property svn:mime-type set to text/x-csrc
File size: 7.8 KB
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1/***************************************************************************
2 * _ _ ____ _
3 * Project ___| | | | _ \| |
4 * / __| | | | |_) | |
5 * | (__| |_| | _ <| |___
6 * \___|\___/|_| \_\_____|
7 *
8 * Copyright (C) 1997 - 2015, Daniel Stenberg, <daniel@haxx.se>, et al.
9 *
10 * This software is licensed as described in the file COPYING, which
11 * you should have received as part of this distribution. The terms
12 * are also available at https://curl.haxx.se/docs/copyright.html.
13 *
14 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
15 * copies of the Software, and permit persons to whom the Software is
16 * furnished to do so, under the terms of the COPYING file.
17 *
18 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
19 * KIND, either express or implied.
20 *
21 ***************************************************************************/
22
23#include "curl_setup.h"
24
25#include "splay.h"
26
27/*
28 * This macro compares two node keys i and j and returns:
29 *
30 * negative value: when i is smaller than j
31 * zero : when i is equal to j
32 * positive when : when i is larger than j
33 */
34#define compare(i,j) Curl_splaycomparekeys((i),(j))
35
36/*
37 * Splay using the key i (which may or may not be in the tree.) The starting
38 * root is t.
39 */
40struct Curl_tree *Curl_splay(struct timeval i,
41 struct Curl_tree *t)
42{
43 struct Curl_tree N, *l, *r, *y;
44 long comp;
45
46 if(t == NULL)
47 return t;
48 N.smaller = N.larger = NULL;
49 l = r = &N;
50
51 for(;;) {
52 comp = compare(i, t->key);
53 if(comp < 0) {
54 if(t->smaller == NULL)
55 break;
56 if(compare(i, t->smaller->key) < 0) {
57 y = t->smaller; /* rotate smaller */
58 t->smaller = y->larger;
59 y->larger = t;
60 t = y;
61 if(t->smaller == NULL)
62 break;
63 }
64 r->smaller = t; /* link smaller */
65 r = t;
66 t = t->smaller;
67 }
68 else if(comp > 0) {
69 if(t->larger == NULL)
70 break;
71 if(compare(i, t->larger->key) > 0) {
72 y = t->larger; /* rotate larger */
73 t->larger = y->smaller;
74 y->smaller = t;
75 t = y;
76 if(t->larger == NULL)
77 break;
78 }
79 l->larger = t; /* link larger */
80 l = t;
81 t = t->larger;
82 }
83 else
84 break;
85 }
86
87 l->larger = t->smaller; /* assemble */
88 r->smaller = t->larger;
89 t->smaller = N.larger;
90 t->larger = N.smaller;
91
92 return t;
93}
94
95/* Insert key i into the tree t. Return a pointer to the resulting tree or
96 * NULL if something went wrong.
97 *
98 * @unittest: 1309
99 */
100struct Curl_tree *Curl_splayinsert(struct timeval i,
101 struct Curl_tree *t,
102 struct Curl_tree *node)
103{
104 static const struct timeval KEY_NOTUSED = {-1, -1}; /* will *NEVER* appear */
105
106 if(node == NULL)
107 return t;
108
109 if(t != NULL) {
110 t = Curl_splay(i, t);
111 if(compare(i, t->key)==0) {
112 /* There already exists a node in the tree with the very same key. Build
113 a linked list of nodes. We make the new 'node' struct the new master
114 node and make the previous node the first one in the 'same' list. */
115
116 node->same = t;
117 node->key = i;
118 node->smaller = t->smaller;
119 node->larger = t->larger;
120
121 t->smaller = node; /* in the sub node for this same key, we use the
122 smaller pointer to point back to the master
123 node */
124
125 t->key = KEY_NOTUSED; /* and we set the key in the sub node to NOTUSED
126 to quickly identify this node as a subnode */
127
128 return node; /* new root node */
129 }
130 }
131
132 if(t == NULL) {
133 node->smaller = node->larger = NULL;
134 }
135 else if(compare(i, t->key) < 0) {
136 node->smaller = t->smaller;
137 node->larger = t;
138 t->smaller = NULL;
139
140 }
141 else {
142 node->larger = t->larger;
143 node->smaller = t;
144 t->larger = NULL;
145 }
146 node->key = i;
147
148 node->same = NULL; /* no identical node (yet) */
149 return node;
150}
151
152/* Finds and deletes the best-fit node from the tree. Return a pointer to the
153 resulting tree. best-fit means the node with the given or lower key */
154struct Curl_tree *Curl_splaygetbest(struct timeval i,
155 struct Curl_tree *t,
156 struct Curl_tree **removed)
157{
158 struct Curl_tree *x;
159
160 if(!t) {
161 *removed = NULL; /* none removed since there was no root */
162 return NULL;
163 }
164
165 t = Curl_splay(i, t);
166 if(compare(i, t->key) < 0) {
167 /* too big node, try the smaller chain */
168 if(t->smaller)
169 t=Curl_splay(t->smaller->key, t);
170 else {
171 /* fail */
172 *removed = NULL;
173 return t;
174 }
175 }
176
177 if(compare(i, t->key) >= 0) { /* found it */
178 /* FIRST! Check if there is a list with identical keys */
179 x = t->same;
180 if(x) {
181 /* there is, pick one from the list */
182
183 /* 'x' is the new root node */
184
185 x->key = t->key;
186 x->larger = t->larger;
187 x->smaller = t->smaller;
188
189 *removed = t;
190 return x; /* new root */
191 }
192
193 if(t->smaller == NULL) {
194 x = t->larger;
195 }
196 else {
197 x = Curl_splay(i, t->smaller);
198 x->larger = t->larger;
199 }
200 *removed = t;
201
202 return x;
203 }
204 else {
205 *removed = NULL; /* no match */
206 return t; /* It wasn't there */
207 }
208}
209
210
211/* Deletes the very node we point out from the tree if it's there. Stores a
212 * pointer to the new resulting tree in 'newroot'.
213 *
214 * Returns zero on success and non-zero on errors! TODO: document error codes.
215 * When returning error, it does not touch the 'newroot' pointer.
216 *
217 * NOTE: when the last node of the tree is removed, there's no tree left so
218 * 'newroot' will be made to point to NULL.
219 *
220 * @unittest: 1309
221 */
222int Curl_splayremovebyaddr(struct Curl_tree *t,
223 struct Curl_tree *removenode,
224 struct Curl_tree **newroot)
225{
226 static const struct timeval KEY_NOTUSED = {-1, -1}; /* will *NEVER* appear */
227 struct Curl_tree *x;
228
229 if(!t || !removenode)
230 return 1;
231
232 if(compare(KEY_NOTUSED, removenode->key) == 0) {
233 /* Key set to NOTUSED means it is a subnode within a 'same' linked list
234 and thus we can unlink it easily. The 'smaller' link of a subnode
235 links to the parent node. */
236 if(removenode->smaller == NULL)
237 return 3;
238
239 removenode->smaller->same = removenode->same;
240 if(removenode->same)
241 removenode->same->smaller = removenode->smaller;
242
243 /* Ensures that double-remove gets caught. */
244 removenode->smaller = NULL;
245
246 /* voila, we're done! */
247 *newroot = t; /* return the same root */
248 return 0;
249 }
250
251 t = Curl_splay(removenode->key, t);
252
253 /* First make sure that we got the same root node as the one we want
254 to remove, as otherwise we might be trying to remove a node that
255 isn't actually in the tree.
256
257 We cannot just compare the keys here as a double remove in quick
258 succession of a node with key != KEY_NOTUSED && same != NULL
259 could return the same key but a different node. */
260 if(t != removenode)
261 return 2;
262
263 /* Check if there is a list with identical sizes, as then we're trying to
264 remove the root node of a list of nodes with identical keys. */
265 x = t->same;
266 if(x) {
267 /* 'x' is the new root node, we just make it use the root node's
268 smaller/larger links */
269
270 x->key = t->key;
271 x->larger = t->larger;
272 x->smaller = t->smaller;
273 }
274 else {
275 /* Remove the root node */
276 if(t->smaller == NULL)
277 x = t->larger;
278 else {
279 x = Curl_splay(removenode->key, t->smaller);
280 x->larger = t->larger;
281 }
282 }
283
284 *newroot = x; /* store new root pointer */
285
286 return 0;
287}
288
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