blob: ff5dd9e876ccdea147de9aa642979fc4722d3971 (
plain)
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
|
/**
* @file heap.c
* A basic memory manager
*
* Copyright (C) 2018 Clyne Sullivan
*
* This program 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.
*
* This program 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 this program. If not, see <https://www.gnu.org/licenses/>.
*/
#include "heap.h"
#define HEAP_ALIGN 4
typedef struct {
uint32_t size;
void *next;
} __attribute__ ((packed)) alloc_t;
static alloc_t *free_blocks;
static void *heap_end;
void heap_init(void *buf)
{
heap_end = buf;
free_blocks = 0;
}
uint32_t heap_free(void)
{
uint32_t total = 0;
for (alloc_t *node = free_blocks; node != 0; node = node->next)
total += node->size;
return total + (0x20018000 - (uint32_t)heap_end);
}
void *malloc(uint32_t size)
{
if (size == 0)
return 0;
size = (size + sizeof(alloc_t) + HEAP_ALIGN) & ~(HEAP_ALIGN - 1);
alloc_t *node = free_blocks;
alloc_t *prev = 0;
while (node != 0) {
if (node->size >= size) {
// get out of the free chain
if (prev != 0)
prev->next = node->next;
else
free_blocks = node->next;
node->next = 0;
// split alloc if too big
if (node->size > size + 64) {
alloc_t *leftover = (alloc_t *)((uint32_t)node
+ sizeof(alloc_t) + size);
leftover->size = node->size - size - sizeof(alloc_t);
leftover->next = 0;
free((uint8_t *)leftover + sizeof(alloc_t));
node->size = size;
return (void *)((uint8_t *)node + sizeof(alloc_t));
}
return (void *)((uint8_t *)node + sizeof(alloc_t));
}
prev = node;
node = node->next;
}
node = (alloc_t *)heap_end;
node->size = size;
node->next = 0;
heap_end = (void *)((uint8_t *)heap_end + size);
return (void *)((uint8_t *)node + sizeof(alloc_t));
}
void *calloc(uint32_t count, uint32_t size)
{
uint8_t *buf = malloc(count * size);
for (uint32_t i = 0; i < count * size; i++)
buf[i] = 0;
return buf;
}
void free(void *buf)
{
if (buf == 0)
return;
alloc_t *alloc = (alloc_t *)((uint8_t *)buf - sizeof(alloc_t));
if (alloc->next != 0)
return;
// check for adjacent free'd blocks
int merged = 0;
for (alloc_t *prev = 0, *node = free_blocks; node != 0; prev = node, node = node->next) {
if ((uint32_t)node + sizeof(alloc_t) + node->size == (uint32_t)alloc) {
// block before
merged |= 1;
node->size += sizeof(alloc_t) + alloc->size;
break;
//alloc = node;
} else if ((uint32_t)buf + alloc->size == (uint32_t)node) {
// block after
merged |= 1;
alloc->size += sizeof(alloc_t) + node->size;
alloc->next = node->next;
if (prev != 0)
prev->next = alloc;
else
free_blocks = alloc;
break;
}
}
if (merged == 0) {
alloc->next = free_blocks;
free_blocks = alloc;
}
}
|
