Working linked memory structure on linux.

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Maxime Bloch 2020-01-28 04:18:03 +01:00
parent 43bab5ff4f
commit ea9f4c6e49
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kernel/linked_list.c Normal file
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#ifndef LINKED_LIST_C
#define LINKED_LIST_C
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
typedef struct ll_node {
void *data;
int size;
bool used;
struct ll_node *previous;
struct ll_node *next;
} ll_node;
ll_node *__new_node() {
ll_node *new_node = malloc(sizeof(ll_node));
new_node->data = NULL;
new_node->size = 0;
new_node->used = false;
new_node->previous = NULL;
new_node->next = NULL;
return new_node;
}
ll_node *__search_ll_node(ll_node *heap_head, void *data) {
ll_node *curr_node = heap_head;
while (!curr_node->used || curr_node->data != data) {
curr_node = curr_node->next;
}
return curr_node;
}
void *__alloc(ll_node *ll_head, int size) {
ll_node *curr_node = ll_head;
ll_node *new_node = __new_node();
new_node->used = true;
new_node->size = size;
while (curr_node->next != NULL) {
curr_node = curr_node->next;
if (!curr_node->used && curr_node->size >= size) {
curr_node->size -= size;
// xxx -> <new_node> -> empty block -> yyy
// link new_node to xxx
curr_node->previous->next = new_node;
new_node->previous = curr_node->previous;
// link new_node to empty_block or yyy
if (curr_node->size == 0) {
new_node->next = curr_node->next;
curr_node->next->previous = new_node;
free(curr_node);
} else {
new_node->next = curr_node;
curr_node->previous = new_node;
}
void *data = new_node->previous->data + new_node->previous->size;
new_node->data = data;
return new_node->data;
}
}
new_node->previous = curr_node;
curr_node->next = new_node;
void *data = new_node->previous->data + new_node->previous->size;
new_node->data = data;
return new_node->data;
}
void __free(ll_node *ll_head, void *data) {
// Search the corresponding block of memory
// TODO This can be held in a table for quicker lookup
ll_node *empty_node = __search_ll_node(ll_head, data);
empty_node->used = false;
// Free the node
if (!empty_node->previous->used) {
empty_node->size += empty_node->previous->size;
empty_node->previous->previous->next = empty_node;
ll_node* previous = empty_node->previous;
empty_node->previous = empty_node->previous->previous;
free(previous);
}
if (!empty_node->next->used) {
empty_node->size += empty_node->next->size;
empty_node->next->next->previous = empty_node;
ll_node* next = empty_node->next;
empty_node->next = empty_node->next->next;
free(next);
}
}
void print(ll_node *ll_head) {
printf("==== MEM DUMP ====\n");
ll_node *curr_node = ll_head;
while (curr_node != NULL) {
if (!curr_node->used) {
printf("empty");
} else {
printf("%p", curr_node->data);
}
printf(" (%d)\n", curr_node->size);
curr_node = curr_node->next;
}
printf("-------------------\n\n");
}
void test_allocs(){
ll_node *ll_head = __new_node();
ll_head->data = malloc(sizeof(size_t) * 1000);
ll_head->used = true;
ll_head->size = 1;
void* ptr0 = __alloc(ll_head, 5);
void* ptr1 = __alloc(ll_head, 5);
void* ptr4 = __alloc(ll_head, 5);
print(ll_head);
printf("Free nr 3\n");
__free(ll_head, ptr1);
print(ll_head);
printf("Alloc 3 bytes\n");
void* ptr2 = __alloc(ll_head, 3);
print(ll_head);
printf("Alloc 3 bytes\n");
__alloc(ll_head, 3);
print(ll_head);
printf("Alloc 2 bytes\n");
void* ptr3 = __alloc(ll_head, 2);
print(ll_head);
__free(ll_head, ptr2);
print(ll_head);
__free(ll_head, ptr4);
print(ll_head);
__free(ll_head, ptr3);
print(ll_head);
__free(ll_head, ptr0);
print(ll_head);
}
int main() {
test_allocs();
}
#endif // LINKED_LIST_C