blob: 0444f78b8f7be0816dcc5764b6eaae0ec1dbc257 (
plain) (
blame)
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
|
#include "talloc.h"
extern void print_s(char *);
extern void print_i(size_t);
extern void print_f(float);
typedef struct Block Block;
struct Block {
void *addr;
Block *next;
size_t size;
};
typedef struct {
Block *free; // first free block
Block *used; // first used block
Block *avail; // first available blank block
size_t top; // top free addr
size_t limit; // heap limit
Block blocks[TA_HEAP_BLOCKS];
} Heap;
static Heap *heap = (Heap *)TA_BASE;
/**
* Insert block into free list, sorted by addr.
*/
static void insert_block(Block *block) {
Block *ptr = heap->free;
Block *prev = NULL;
while (ptr != NULL) {
if ((size_t)block->addr <= (size_t)ptr->addr) {
print_s("insert");
print_i((size_t)ptr);
break;
}
prev = ptr;
ptr = ptr->next;
}
if (prev != NULL) {
if (ptr == NULL) {
print_s("new tail");
}
prev->next = block;
} else {
print_s("new head");
heap->free = block;
}
block->next = ptr;
}
static void release_blocks(Block *scan, Block *to) {
Block *scan_next;
while (scan != to) {
print_s("release");
print_i((size_t)scan);
scan_next = scan->next;
scan->next = heap->avail;
scan->addr = 0;
scan->size = 0;
heap->avail = scan;
scan = scan_next;
}
}
static void compress() {
Block *ptr = heap->free;
Block *prev = NULL;
Block *scan;
while (ptr != NULL) {
prev = ptr;
scan = ptr->next;
size_t base = (size_t)ptr->addr;
while (scan != NULL &&
(size_t)prev->addr + prev->size == (size_t)scan->addr) {
print_s("merge");
print_i((size_t)scan);
prev = scan;
scan = scan->next;
}
if (prev != ptr) {
size_t new_size = prev->addr + prev->size - ptr->addr;
print_s("new size");
print_i(new_size);
ptr->size = new_size;
Block *next = prev->next;
// make merged blocks available
release_blocks(ptr->next, prev->next);
// relink
ptr->next = next;
ptr = next;
} else {
ptr = ptr->next;
}
}
}
bool talloc_init() {
heap->free = NULL;
heap->used = NULL;
heap->avail = heap->blocks;
heap->top = TA_BASE + sizeof(Heap);
heap->limit = TA_HEAP_LIMIT;
Block *block = heap->blocks;
for (size_t i = TA_HEAP_BLOCKS - 1; i > 0; i--) {
block->next = block + 1;
block++;
}
return true;
}
bool talloc_free(void *free) {
Block *block = heap->used;
Block *prev = NULL;
while (block != NULL) {
if (free == block->addr) {
if (prev) {
prev->next = block->next;
} else {
heap->used = block->next;
}
insert_block(block);
compress();
return true;
}
prev = block;
block = block->next;
}
return false;
}
void *talloc(size_t num) {
Block *ptr = heap->free;
Block *prev = NULL;
size_t top = heap->top;
num = (num + TA_ALIGN - 1) & -TA_ALIGN;
while (ptr != NULL) {
const int is_top = (size_t)ptr->addr + ptr->size >= top;
if (is_top || ptr->size >= num) {
if (prev != NULL) {
prev->next = ptr->next;
} else {
heap->free = ptr->next;
}
ptr->next = heap->used;
heap->used = ptr;
if (is_top) {
print_s("resize top block");
ptr->size = num;
heap->top = (size_t)ptr->addr + num;
} else if (heap->avail != NULL) {
size_t excess = ptr->size - num;
if (excess >= TA_ALIGN) {
ptr->size = num;
Block *split = heap->avail;
heap->avail = split->next;
split->addr = ptr->addr + num;
print_s("split");
print_i((size_t)split->addr);
split->size = excess;
insert_block(split);
compress();
}
}
return ptr->addr;
}
prev = ptr;
ptr = ptr->next;
}
// no matching free blocks
// see if any other blocks available
size_t new_top = top + num;
if (heap->avail != NULL && new_top <= heap->limit) {
ptr = heap->avail;
heap->avail = ptr->next;
ptr->addr = (void *)top;
ptr->next = heap->used;
ptr->size = num;
heap->used = ptr;
heap->top = new_top;
return ptr->addr;
}
return NULL;
}
static size_t count_blocks(Block *ptr) {
size_t num = 0;
while (ptr != NULL) {
num++;
ptr = ptr->next;
}
return num;
}
size_t talloc_num_free() {
return count_blocks(heap->free);
}
size_t talloc_num_used() {
return count_blocks(heap->used);
}
size_t talloc_num_avail() {
return count_blocks(heap->avail);
}
bool talloc_check() {
return TA_HEAP_BLOCKS ==
talloc_num_free() + talloc_num_used() + talloc_num_avail();
}
|
