tabs/kernel/linked_list.c

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C
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#ifndef LINKED_LIST_C
#define LINKED_LIST_C
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
typedef struct page_tag {
size_t size;
struct page_tag *prev;
struct page_tag *next;
} page_tag;
page_tag *start;
page_tag *__searchPage(void *data) {
page_tag *curr_page = start;
while (curr_page + (sizeof(page_tag)) != data) {
curr_page = curr_page->next;
}
return curr_page;
}
///**
// * @param alignment
// * @param size
// * @return A block aligned with the alignment parameter.
// */
//void* aligned_alloc(int alignment, int size){
// // TODO
// return NULL;
//}
void *__alloc(size_t size) {
page_tag *curr_page = start;
while (curr_page->next != NULL) {
page_tag *new_page = ((void *) curr_page) + sizeof(page_tag) + curr_page->size;
if ((void *) new_page + sizeof(page_tag) + size <= curr_page->next) {
new_page->size = size;
curr_page->next->prev = new_page;
new_page->next = curr_page->next;
curr_page->next = new_page;
new_page->prev = curr_page;
return new_page + 1;
}
curr_page = curr_page->next;
}
page_tag *new_page = ((void *) curr_page) + sizeof(page_tag) + curr_page->size;
new_page->size = size;
curr_page->next = new_page;
new_page->prev = curr_page;
return new_page + 1;
}
void __free(void *data) {
page_tag *data_tag = data - sizeof(page_tag);
printf("found tag at %p\n", data_tag);
data_tag->prev->next = data_tag->next;
data_tag->next->prev = data_tag->prev;
}
void print() {
printf("==== MEM DUMP ====\n");
page_tag *curr_page = start;
int i = 0;
while (curr_page != NULL) {
printf("%d: [%p (%zu)] [%p (%zu)]\n",
i,
curr_page, sizeof(page_tag),
curr_page + 1, curr_page->size);
void *empty_start = (void *) curr_page + sizeof(page_tag) + curr_page->size;
if (empty_start + sizeof(page_tag) < (void *) curr_page->next) {
printf("empty_page (%ld, %ld)\n",
sizeof(page_tag),
(void *) curr_page->next -
(empty_start + sizeof(page_tag)));
} else if (empty_start < (void *) curr_page->next) {
printf("not enough room (%ld)\n",
(void *) curr_page->next - empty_start);
}
curr_page = curr_page->next;
i++;
}
printf("-------------------\n\n");
}
void test_allocs() {
void *ptr0 = __alloc(64);
void *ptr1 = __alloc(64);
void *ptr4 = __alloc(64);
print();
printf("Free nr 2 -> %p\n", ptr1);
__free(ptr1);
print();
printf("Alloc 32 bytes\n");
void *ptr2 = __alloc(32);
print();
printf("Alloc 32 bytes\n");
__alloc(32);
print();
printf("Alloc 8 bytes\n");
void *ptr3 = __alloc(8);
print();
__free(ptr2);
print();
__free(ptr4);
print();
__free(ptr3);
print();
__free(ptr0);
print();
printf("#########\nTry almost fill\n");
__alloc(160);
print();
__alloc(50);
print();
}
int main() {
start = malloc(sizeof(size_t) * 1000);
start->next = NULL;
start->prev = NULL;
test_allocs();
}
#endif // LINKED_LIST_C