Refactor to holding linked list data before the alloced blocks.
These "tags" hold the pointers between the alloced blocks.
This commit is contained in:
Maxime Bloch
parent
ea9f4c6e49
commit
fafe06ed2b
2 changed files with 102 additions and 118 deletions
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@ -290,7 +290,7 @@ repnz movsd
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or ax, ax
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jnz .elf_ph_loop
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.start_kernel
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.start_kernel:
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cmp edi, KERNEL_START
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je .invalid_elf
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@ -5,159 +5,143 @@
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#include <stdio.h>
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#include <stdlib.h>
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typedef struct ll_node {
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void *data;
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int size;
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bool used;
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typedef struct page_tag {
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size_t size;
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struct ll_node *previous;
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struct ll_node *next;
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} ll_node;
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struct page_tag *prev;
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struct page_tag *next;
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} page_tag;
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ll_node *__new_node() {
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ll_node *new_node = malloc(sizeof(ll_node));
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new_node->data = NULL;
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new_node->size = 0;
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new_node->used = false;
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new_node->previous = NULL;
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new_node->next = NULL;
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return new_node;
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page_tag *start;
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page_tag *__searchPage(void *data) {
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page_tag *curr_page = start;
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while (curr_page + (sizeof(page_tag)) != data) {
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curr_page = curr_page->next;
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}
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return curr_page;
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}
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ll_node *__search_ll_node(ll_node *heap_head, void *data) {
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ll_node *curr_node = heap_head;
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while (!curr_node->used || curr_node->data != data) {
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curr_node = curr_node->next;
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///**
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// * @param alignment
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// * @param size
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// * @return A block aligned with the alignment parameter.
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// */
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//void* aligned_alloc(int alignment, int size){
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// // TODO
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// return NULL;
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//}
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void *__alloc(size_t size) {
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page_tag *curr_page = start;
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while (curr_page->next != NULL) {
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page_tag *new_page = ((void *) curr_page) + sizeof(page_tag) + curr_page->size;
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if ((void *) new_page + sizeof(page_tag) + size <= curr_page->next) {
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new_page->size = size;
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curr_page->next->prev = new_page;
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new_page->next = curr_page->next;
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curr_page->next = new_page;
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new_page->prev = curr_page;
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return new_page + 1;
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}
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return curr_node;
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curr_page = curr_page->next;
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}
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page_tag *new_page = ((void *) curr_page) + sizeof(page_tag) + curr_page->size;
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new_page->size = size;
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curr_page->next = new_page;
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new_page->prev = curr_page;
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return new_page + 1;
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}
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void *__alloc(ll_node *ll_head, int size) {
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ll_node *curr_node = ll_head;
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ll_node *new_node = __new_node();
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new_node->used = true;
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new_node->size = size;
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void __free(void *data) {
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page_tag *data_tag = data - sizeof(page_tag);
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printf("found tag at %p\n", data_tag);
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while (curr_node->next != NULL) {
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curr_node = curr_node->next;
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if (!curr_node->used && curr_node->size >= size) {
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curr_node->size -= size;
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// xxx -> <new_node> -> empty block -> yyy
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// link new_node to xxx
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curr_node->previous->next = new_node;
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new_node->previous = curr_node->previous;
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// link new_node to empty_block or yyy
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if (curr_node->size == 0) {
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new_node->next = curr_node->next;
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curr_node->next->previous = new_node;
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free(curr_node);
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} else {
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new_node->next = curr_node;
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curr_node->previous = new_node;
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}
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void *data = new_node->previous->data + new_node->previous->size;
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new_node->data = data;
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return new_node->data;
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}
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}
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new_node->previous = curr_node;
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curr_node->next = new_node;
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void *data = new_node->previous->data + new_node->previous->size;
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new_node->data = data;
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return new_node->data;
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data_tag->prev->next = data_tag->next;
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data_tag->next->prev = data_tag->prev;
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}
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void __free(ll_node *ll_head, void *data) {
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// Search the corresponding block of memory
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// TODO This can be held in a table for quicker lookup
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ll_node *empty_node = __search_ll_node(ll_head, data);
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empty_node->used = false;
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// Free the node
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if (!empty_node->previous->used) {
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empty_node->size += empty_node->previous->size;
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empty_node->previous->previous->next = empty_node;
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ll_node* previous = empty_node->previous;
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empty_node->previous = empty_node->previous->previous;
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free(previous);
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}
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if (!empty_node->next->used) {
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empty_node->size += empty_node->next->size;
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empty_node->next->next->previous = empty_node;
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ll_node* next = empty_node->next;
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empty_node->next = empty_node->next->next;
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free(next);
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}
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}
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void print(ll_node *ll_head) {
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void print() {
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printf("==== MEM DUMP ====\n");
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ll_node *curr_node = ll_head;
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while (curr_node != NULL) {
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if (!curr_node->used) {
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printf("empty");
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} else {
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printf("%p", curr_node->data);
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}
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printf(" (%d)\n", curr_node->size);
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page_tag *curr_page = start;
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int i = 0;
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while (curr_page != NULL) {
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printf("%d: [%p (%zu)] [%p (%zu)]\n",
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i,
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curr_page, sizeof(page_tag),
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curr_page + 1, curr_page->size);
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curr_node = curr_node->next;
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void *empty_start = (void *) curr_page + sizeof(page_tag) + curr_page->size;
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if (empty_start + sizeof(page_tag) < (void *) curr_page->next) {
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printf("empty_page (%ld, %ld)\n",
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sizeof(page_tag),
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(void *) curr_page->next -
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(empty_start + sizeof(page_tag)));
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} else if (empty_start < (void *) curr_page->next) {
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printf("not enough room (%ld)\n",
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(void *) curr_page->next - empty_start);
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}
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curr_page = curr_page->next;
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i++;
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}
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printf("-------------------\n\n");
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}
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void test_allocs(){
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ll_node *ll_head = __new_node();
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ll_head->data = malloc(sizeof(size_t) * 1000);
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ll_head->used = true;
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ll_head->size = 1;
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void* ptr0 = __alloc(ll_head, 5);
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void* ptr1 = __alloc(ll_head, 5);
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void* ptr4 = __alloc(ll_head, 5);
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print(ll_head);
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void test_allocs() {
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void *ptr0 = __alloc(64);
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void *ptr1 = __alloc(64);
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void *ptr4 = __alloc(64);
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print();
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printf("Free nr 3\n");
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__free(ll_head, ptr1);
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print(ll_head);
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printf("Free nr 2 -> %p\n", ptr1);
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__free(ptr1);
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print();
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printf("Alloc 3 bytes\n");
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void* ptr2 = __alloc(ll_head, 3);
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print(ll_head);
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printf("Alloc 32 bytes\n");
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void *ptr2 = __alloc(32);
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print();
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printf("Alloc 3 bytes\n");
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__alloc(ll_head, 3);
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print(ll_head);
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printf("Alloc 32 bytes\n");
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__alloc(32);
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print();
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printf("Alloc 2 bytes\n");
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void* ptr3 = __alloc(ll_head, 2);
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print(ll_head);
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printf("Alloc 8 bytes\n");
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void *ptr3 = __alloc(8);
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print();
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__free(ptr2);
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print();
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__free(ptr4);
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print();
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__free(ptr3);
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print();
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__free(ptr0);
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print();
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printf("#########\nTry almost fill\n");
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__alloc(160);
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print();
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__alloc(50);
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print();
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__free(ll_head, ptr2);
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print(ll_head);
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__free(ll_head, ptr4);
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print(ll_head);
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__free(ll_head, ptr3);
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print(ll_head);
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__free(ll_head, ptr0);
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print(ll_head);
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}
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int main() {
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start = malloc(sizeof(size_t) * 1000);
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start->next = NULL;
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start->prev = NULL;
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test_allocs();
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}
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