os/kernel/heap.c

89 lines
1.8 KiB
C

#include <stdint.h>
#include <kernel/heap.h>
#include <debugging.h>
#define HEAP_SIZE (4096)
uint8_t* global_heap_data[HEAP_SIZE + sizeof(struct Heap_Block)];
struct Heap_Metadata global_heap;
void heap_init()
{
global_heap.size = HEAP_SIZE;
global_heap.start = (struct Heap_Block*) global_heap_data;
struct Heap_Block* start = global_heap.start;
start->size = HEAP_SIZE;
start->used = false;
start->data = start + 1;
start->next = 0;
}
void* malloc(size_t size)
{
struct Heap_Block* current = global_heap.start;
while (true) {
if (current->used || current->size < size) {
current = current->next;
continue;
}
if (current == 0) {
return 0;
}
struct Heap_Block* next = current->data + size;
next->next = current->next;
next->size = current->size - size - sizeof(struct Heap_Block);
next->data = next + 1;
current->next = next;
current->size = size;
current->used = true;
return current->data;
}
}
void free(void *ptr)
{
struct Heap_Block* current = global_heap.start;
struct Heap_Block* first_unused;
bool found_unused = false;
while (current->data != ptr) {
if (!current->used && !found_unused) {
first_unused = current;
found_unused = true;
} else {
found_unused = false;
}
current = current->next;
}
if (!found_unused) {
first_unused = current;
}
current->used = false;
if (current->next == 0) {
return;
}
struct Heap_Block* start = first_unused;
current = start;
while (current->used == false && current->next != 0) {
current = current->next;
}
start->next = current;
start->size = (uint32_t)start->next - (uint32_t)start->data;
}