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
|
/*
* GRUB -- GRand Unified Bootloader
* Copyright (C) 2011 Free Software Foundation, Inc.
*
* GRUB 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 3 of the License, or
* (at your option) any later version.
*
* GRUB 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 GRUB. If not, see <http://www.gnu.org/licenses/>.
*/
#include <grub/priority_queue.h>
#include <grub/mm.h>
#include <grub/dl.h>
GRUB_MOD_LICENSE ("GPLv3+");
struct grub_priority_queue
{
grub_size_t elsize;
grub_size_t allocated;
grub_size_t used;
grub_comparator_t cmp;
void *els;
};
static inline void *
element (struct grub_priority_queue *pq, grub_size_t k)
{
return ((grub_uint8_t *) pq->els) + k * pq->elsize;
}
static inline void
swap (struct grub_priority_queue *pq, grub_size_t m, grub_size_t n)
{
grub_uint8_t *p1, *p2;
grub_size_t l;
p1 = (grub_uint8_t *) element (pq, m);
p2 = (grub_uint8_t *) element (pq, n);
for (l = pq->elsize; l; l--, p1++, p2++)
{
grub_uint8_t t;
t = *p1;
*p1 = *p2;
*p2 = t;
}
}
static inline grub_size_t
parent (grub_size_t v)
{
return (v - 1) / 2;
}
static inline grub_size_t
left_child (grub_size_t v)
{
return 2 * v + 1;
}
static inline grub_size_t
right_child (grub_size_t v)
{
return 2 * v + 2;
}
void *
grub_priority_queue_top (grub_priority_queue_t pq)
{
if (!pq->used)
return 0;
return element (pq, 0);
}
void
grub_priority_queue_destroy (grub_priority_queue_t pq)
{
grub_free (pq->els);
grub_free (pq);
}
grub_priority_queue_t
grub_priority_queue_new (grub_size_t elsize,
grub_comparator_t cmp)
{
struct grub_priority_queue *ret;
void *els;
els = grub_calloc (8, elsize);
if (!els)
return 0;
ret = (struct grub_priority_queue *) grub_malloc (sizeof (*ret));
if (!ret)
{
grub_free (els);
return 0;
}
ret->elsize = elsize;
ret->allocated = 8;
ret->used = 0;
ret->cmp = cmp;
ret->els = els;
return ret;
}
/* Heap property: pq->cmp (element (pq, p), element (pq, parent (p))) <= 0. */
grub_err_t
grub_priority_queue_push (grub_priority_queue_t pq, const void *el)
{
grub_size_t p;
if (pq->used == pq->allocated)
{
void *els;
els = grub_realloc (pq->els, pq->elsize * 2 * pq->allocated);
if (!els)
return grub_errno;
pq->allocated *= 2;
pq->els = els;
}
pq->used++;
grub_memcpy (element (pq, pq->used - 1), el, pq->elsize);
for (p = pq->used - 1; p; p = parent (p))
{
if (pq->cmp (element (pq, p), element (pq, parent (p))) <= 0)
break;
swap (pq, p, parent (p));
}
return GRUB_ERR_NONE;
}
void
grub_priority_queue_pop (grub_priority_queue_t pq)
{
grub_size_t p;
swap (pq, 0, pq->used - 1);
pq->used--;
for (p = 0; left_child (p) < pq->used; )
{
grub_size_t c;
if (pq->cmp (element (pq, left_child (p)), element (pq, p)) <= 0
&& (right_child (p) >= pq->used
|| pq->cmp (element (pq, right_child (p)), element (pq, p)) <= 0))
break;
if (right_child (p) >= pq->used
|| pq->cmp (element (pq, left_child (p)),
element (pq, right_child (p))) > 0)
c = left_child (p);
else
c = right_child (p);
swap (pq, p, c);
p = c;
}
}
|
