/
heap.c
217 lines (173 loc) · 4.83 KB
/
heap.c
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
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
// SPDX-FileCopyrightText: © 2020 Georg Sauthoff <mail@gms.tf>
// SPDX-License-Identifier: BSL-1.0
#include <stdint.h> // SIZE_MAX
#include "heap.h"
enum { CHILD, PARENT };
GMS_HEAP_STATIC size_t gms_heap_parent_k(size_t i, size_t k)
{
return (i - 1) / k;
}
// returns left child
// +1 for the right child, etc.
GMS_HEAP_STATIC size_t gms_heap_child_k(size_t i, size_t k)
{
return k * i + 1;
}
GMS_HEAP_STATIC size_t gms_heap_parent(size_t i)
{
return gms_heap_parent_k(i, 2);
}
// returns left child
// +1 for the right child
GMS_HEAP_STATIC size_t gms_heap_child(size_t i)
{
return gms_heap_child_k(i, 2);
}
GMS_HEAP_STATIC size_t gms_heap_idx(bool lookup_parent, size_t i)
{
if (lookup_parent)
return gms_heap_parent(i);
else
return gms_heap_child(i);
}
// we are assuming sane sizes here, i.e. page_size and element size
// are a power of two
// NB: - page size is specified in #elements that fit into a page
// - i indexes elements (not bytes)
// - for the first page: the last element isn't used
// - for other pages: the first and last element aren't used
GMS_HEAP_STATIC size_t gms_bheap_child(size_t iP, size_t page_size)
{
size_t page = iP / page_size;
size_t page_start = page * page_size;
size_t next_page_start = (page + 1) * page_size;
size_t i = iP - page_start;
size_t c = gms_heap_child(i);
if (c + 1 < next_page_start)
return page_start + c;
// /2 -> we put both siblings into one page
size_t next_level_off = (c - (page_size - 1)) / 2;
// #elements in the last level of the page
size_t page_ways = page_size / 2;
size_t k = gms_heap_child_k(page, page_ways);
// skip root node element in that page
size_t x = (k + next_level_off) * page_size + 1;
return x;
}
GMS_HEAP_STATIC size_t gms_bheap_parent(size_t iP, size_t page_size)
{
size_t page = iP / page_size;
size_t page_start = page * page_size;
size_t i = iP - page_start;
size_t p = gms_heap_parent(i);
if (p || !page)
return page_start + p;
size_t page_ways = page_size / 2;
size_t q = gms_heap_parent_k(page, page_ways);
size_t off = (page - 1) % page_ways;
size_t x = q * page_size + page_size - 1 - page_ways + off;
return x;
}
GMS_HEAP_STATIC size_t gms_heap_next(size_t i)
{
return i + 1;
}
GMS_HEAP_STATIC size_t gms_bheap_next(size_t i, size_t page_size)
{
++i;
size_t k = i % page_size;
if (!k)
++i;
else if (k + 1 == page_size)
i += 2;
return i;
}
GMS_HEAP_STATIC void gms_heap_ify(void *p, size_t i, size_t n,
Gms_Heap_Idx_Func idx,
Gms_Heap_Cmp_Func gt, Gms_Heap_Swap_Func swap, void *user)
{
if (n < 2)
return;
for (;;) {
size_t maxi = i;
size_t l = idx(CHILD, i);
size_t r = l + 1;
if (l < n && gt(p, l, i))
maxi = l;
if (r < n && gt(p, r, maxi))
maxi = r;
if (maxi == i)
return;
swap(p, i, maxi, user);
i = maxi;
}
}
GMS_HEAP_STATIC void gms_heap_ify_up(void *p, size_t i,
Gms_Heap_Idx_Func idx,
Gms_Heap_Cmp_Func gt, Gms_Heap_Swap_Func swap, void *user)
{
while (i > 0) {
size_t j = idx(PARENT, i);
if (gt(p, i, j)) {
swap(p, i, j, user);
i = j;
} else {
break;
}
}
}
GMS_HEAP_STATIC void gms_heap_build(void *p, size_t n,
Gms_Heap_Cmp_Func gt, Gms_Heap_Swap_Func swap, void *user)
{
if (n < 2)
return;
for (size_t i = n / 2 - 1; i != SIZE_MAX; --i)
gms_heap_ify(p, i, n, gms_heap_idx, gt, swap, user);
}
GMS_HEAP_STATIC bool gms_heap_is_heap(void *p, size_t i, size_t n,
Gms_Heap_Cmp_Func gt)
{
if (n < 2)
return true;
size_t first = n / 2 - 1;
if (i > first)
return true;
for (; i < first; ++i) {
size_t l = gms_heap_child(i);
size_t r = l + 1;
if (gt(p, l, i))
return false;
if (gt(p, r, i))
return false;
}
i = first;
size_t l = gms_heap_child(i);
size_t r = l + 1;
if (gt(p, l, i))
return false;
if (r < n && gt(p, r, i))
return false;
return true;
}
GMS_HEAP_STATIC void gms_heap_remove(void *p, size_t i, size_t n,
Gms_Heap_Idx_Func idx,
Gms_Heap_Cmp_Func gt, Gms_Heap_Move_Func mv, Gms_Heap_Swap_Func swap,
void *user)
{
//assert(i < n);
--n;
if (i == n)
return;
bool is_gt = gt(p, n, i);
mv(p, i, n, user);
if (is_gt)
gms_heap_ify_up(p, i, idx, gt, swap, user);
else
gms_heap_ify(p, i, n, idx, gt, swap, user);
}
GMS_HEAP_STATIC void gms_heap_insert(void *p, size_t n,
Gms_Heap_Idx_Func idx,
Gms_Heap_Cmp_Func gt, Gms_Heap_Swap_Func swap, void *user)
{
gms_heap_ify_up(p, n, idx, gt, swap, user);
}