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
|
/*
* Copyright (C) 2009-2012 the libgit2 contributors
*
* This file is part of libgit2, distributed under the GNU GPL v2 with
* a Linking Exception. For full terms see the included COPYING file.
*/
#include "common.h"
#include "pqueue.h"
#define left(i) ((i) << 1)
#define right(i) (((i) << 1) + 1)
#define parent(i) ((i) >> 1)
int git_pqueue_init(git_pqueue *q, size_t n, git_pqueue_cmp cmppri)
{
assert(q);
/* Need to allocate n+1 elements since element 0 isn't used. */
if ((q->d = git__malloc((n + 1) * sizeof(void *))) == NULL)
return GIT_ENOMEM;
q->size = 1;
q->avail = q->step = (n + 1); /* see comment above about n+1 */
q->cmppri = cmppri;
return GIT_SUCCESS;
}
void git_pqueue_free(git_pqueue *q)
{
git__free(q->d);
q->d = NULL;
}
void git_pqueue_clear(git_pqueue *q)
{
q->size = 1;
}
size_t git_pqueue_size(git_pqueue *q)
{
/* queue element 0 exists but doesn't count since it isn't used. */
return (q->size - 1);
}
static void bubble_up(git_pqueue *q, size_t i)
{
size_t parent_node;
void *moving_node = q->d[i];
for (parent_node = parent(i);
((i > 1) && q->cmppri(q->d[parent_node], moving_node));
i = parent_node, parent_node = parent(i)) {
q->d[i] = q->d[parent_node];
}
q->d[i] = moving_node;
}
static size_t maxchild(git_pqueue *q, size_t i)
{
size_t child_node = left(i);
if (child_node >= q->size)
return 0;
if ((child_node + 1) < q->size &&
q->cmppri(q->d[child_node], q->d[child_node + 1]))
child_node++; /* use right child instead of left */
return child_node;
}
static void percolate_down(git_pqueue *q, size_t i)
{
size_t child_node;
void *moving_node = q->d[i];
while ((child_node = maxchild(q, i)) != 0 &&
q->cmppri(moving_node, q->d[child_node])) {
q->d[i] = q->d[child_node];
i = child_node;
}
q->d[i] = moving_node;
}
int git_pqueue_insert(git_pqueue *q, void *d)
{
void *tmp;
size_t i;
size_t newsize;
if (!q) return 1;
/* allocate more memory if necessary */
if (q->size >= q->avail) {
newsize = q->size + q->step;
if ((tmp = git__realloc(q->d, sizeof(void *) * newsize)) == NULL)
return GIT_ENOMEM;
q->d = tmp;
q->avail = newsize;
}
/* insert item */
i = q->size++;
q->d[i] = d;
bubble_up(q, i);
return GIT_SUCCESS;
}
void *git_pqueue_pop(git_pqueue *q)
{
void *head;
if (!q || q->size == 1)
return NULL;
head = q->d[1];
q->d[1] = q->d[--q->size];
percolate_down(q, 1);
return head;
}
void *git_pqueue_peek(git_pqueue *q)
{
if (!q || q->size == 1)
return NULL;
return q->d[1];
}
|
