File: prio-queue.c

package info (click to toggle)
git 1:2.20.1-2+deb10u3
  • links: PTS, VCS
  • area: main
  • in suites: buster
  • size: 45,676 kB
  • sloc: ansic: 210,769; sh: 180,432; perl: 29,102; tcl: 21,663; python: 6,143; makefile: 3,700; sed: 189; php: 120; asm: 98; csh: 45; ruby: 24; lisp: 12
file content (96 lines) | stat: -rw-r--r-- 2,057 bytes parent folder | download | duplicates (7)
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
#include "cache.h"
#include "prio-queue.h"

static inline int compare(struct prio_queue *queue, int i, int j)
{
	int cmp = queue->compare(queue->array[i].data, queue->array[j].data,
				 queue->cb_data);
	if (!cmp)
		cmp = queue->array[i].ctr - queue->array[j].ctr;
	return cmp;
}

static inline void swap(struct prio_queue *queue, int i, int j)
{
	SWAP(queue->array[i], queue->array[j]);
}

void prio_queue_reverse(struct prio_queue *queue)
{
	int i, j;

	if (queue->compare != NULL)
		BUG("prio_queue_reverse() on non-LIFO queue");
	for (i = 0; i < (j = (queue->nr - 1) - i); i++)
		swap(queue, i, j);
}

void clear_prio_queue(struct prio_queue *queue)
{
	FREE_AND_NULL(queue->array);
	queue->nr = 0;
	queue->alloc = 0;
	queue->insertion_ctr = 0;
}

void prio_queue_put(struct prio_queue *queue, void *thing)
{
	int ix, parent;

	/* Append at the end */
	ALLOC_GROW(queue->array, queue->nr + 1, queue->alloc);
	queue->array[queue->nr].ctr = queue->insertion_ctr++;
	queue->array[queue->nr].data = thing;
	queue->nr++;
	if (!queue->compare)
		return; /* LIFO */

	/* Bubble up the new one */
	for (ix = queue->nr - 1; ix; ix = parent) {
		parent = (ix - 1) / 2;
		if (compare(queue, parent, ix) <= 0)
			break;

		swap(queue, parent, ix);
	}
}

void *prio_queue_get(struct prio_queue *queue)
{
	void *result;
	int ix, child;

	if (!queue->nr)
		return NULL;
	if (!queue->compare)
		return queue->array[--queue->nr].data; /* LIFO */

	result = queue->array[0].data;
	if (!--queue->nr)
		return result;

	queue->array[0] = queue->array[queue->nr];

	/* Push down the one at the root */
	for (ix = 0; ix * 2 + 1 < queue->nr; ix = child) {
		child = ix * 2 + 1; /* left */
		if (child + 1 < queue->nr &&
		    compare(queue, child, child + 1) >= 0)
			child++; /* use right child */

		if (compare(queue, ix, child) <= 0)
			break;

		swap(queue, child, ix);
	}
	return result;
}

void *prio_queue_peek(struct prio_queue *queue)
{
	if (!queue->nr)
		return NULL;
	if (!queue->compare)
		return queue->array[queue->nr - 1].data;
	return queue->array[0].data;
}