1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
|
/* Priority queue functions.
* Copyright (C) 2003 Yasuhiro Ohara
*
* This file is part of GNU Zebra.
*
* GNU Zebra is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published
* by the Free Software Foundation; either version 2, or (at your
* option) any later version.
*
* GNU Zebra is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; see the file COPYING; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <zebra.h>
#include "memory.h"
#include "pqueue.h"
DEFINE_MTYPE_STATIC(LIB, PQUEUE, "Priority queue")
DEFINE_MTYPE_STATIC(LIB, PQUEUE_DATA, "Priority queue data")
/* priority queue using heap sort */
/* pqueue->cmp() controls the order of sorting (i.e, ascending or
descending). If you want the left node to move upper of the heap
binary tree, make cmp() to return less than 0. for example, if cmp
(10, 20) returns -1, the sorting is ascending order. if cmp (10,
20) returns 1, the sorting is descending order. if cmp (10, 20)
returns 0, this library does not do sorting (which will not be what
you want). To be brief, if the contents of cmp_func (left, right)
is left - right, dequeue () returns the smallest node. Otherwise
(if the contents is right - left), dequeue () returns the largest
node. */
#define DATA_SIZE (sizeof (void *))
#define PARENT_OF(x) ((x - 1) / 2)
#define LEFT_OF(x) (2 * x + 1)
#define RIGHT_OF(x) (2 * x + 2)
#define HAVE_CHILD(x,q) (x < (q)->size / 2)
void trickle_up(int index, struct pqueue *queue)
{
void *tmp;
/* Save current node as tmp node. */
tmp = queue->array[index];
/* Continue until the node reaches top or the place where the parent
node should be upper than the tmp node. */
while (index > 0
&& (*queue->cmp)(tmp, queue->array[PARENT_OF(index)]) < 0) {
/* actually trickle up */
queue->array[index] = queue->array[PARENT_OF(index)];
if (queue->update != NULL)
(*queue->update)(queue->array[index], index);
index = PARENT_OF(index);
}
/* Restore the tmp node to appropriate place. */
queue->array[index] = tmp;
if (queue->update != NULL)
(*queue->update)(tmp, index);
}
void trickle_down(int index, struct pqueue *queue)
{
void *tmp;
int which;
/* Save current node as tmp node. */
tmp = queue->array[index];
/* Continue until the node have at least one (left) child. */
while (HAVE_CHILD(index, queue)) {
/* If right child exists, and if the right child is more proper
to be moved upper. */
if (RIGHT_OF(index) < queue->size
&& (*queue->cmp)(queue->array[LEFT_OF(index)],
queue->array[RIGHT_OF(index)])
> 0)
which = RIGHT_OF(index);
else
which = LEFT_OF(index);
/* If the tmp node should be upper than the child, break. */
if ((*queue->cmp)(queue->array[which], tmp) > 0)
break;
/* Actually trickle down the tmp node. */
queue->array[index] = queue->array[which];
if (queue->update != NULL)
(*queue->update)(queue->array[index], index);
index = which;
}
/* Restore the tmp node to appropriate place. */
queue->array[index] = tmp;
if (queue->update != NULL)
(*queue->update)(tmp, index);
}
struct pqueue *pqueue_create(void)
{
struct pqueue *queue;
queue = XCALLOC(MTYPE_PQUEUE, sizeof(struct pqueue));
queue->array =
XCALLOC(MTYPE_PQUEUE_DATA, DATA_SIZE * PQUEUE_INIT_ARRAYSIZE);
queue->array_size = PQUEUE_INIT_ARRAYSIZE;
/* By default we want nothing to happen when a node changes. */
queue->update = NULL;
return queue;
}
void pqueue_delete(struct pqueue *queue)
{
XFREE(MTYPE_PQUEUE_DATA, queue->array);
XFREE(MTYPE_PQUEUE, queue);
}
static int pqueue_expand(struct pqueue *queue)
{
void **newarray;
newarray =
XCALLOC(MTYPE_PQUEUE_DATA, queue->array_size * DATA_SIZE * 2);
if (newarray == NULL)
return 0;
memcpy(newarray, queue->array, queue->array_size * DATA_SIZE);
XFREE(MTYPE_PQUEUE_DATA, queue->array);
queue->array = newarray;
queue->array_size *= 2;
return 1;
}
void pqueue_enqueue(void *data, struct pqueue *queue)
{
if (queue->size + 2 >= queue->array_size && !pqueue_expand(queue))
return;
queue->array[queue->size] = data;
if (queue->update != NULL)
(*queue->update)(data, queue->size);
trickle_up(queue->size, queue);
queue->size++;
}
void *pqueue_dequeue(struct pqueue *queue)
{
void *data = queue->array[0];
queue->array[0] = queue->array[--queue->size];
trickle_down(0, queue);
return data;
}
void pqueue_remove_at(int index, struct pqueue *queue)
{
queue->array[index] = queue->array[--queue->size];
if (index > 0
&& (*queue->cmp)(queue->array[index],
queue->array[PARENT_OF(index)])
< 0) {
trickle_up(index, queue);
} else {
trickle_down(index, queue);
}
}
void pqueue_remove(void *data, struct pqueue *queue)
{
for (int i = 0; i < queue->size; i++)
if (queue->array[i] == data)
pqueue_remove_at(i, queue);
}
|
