dmmlib/custom_malloc.c

#include <stdio.h>
#include "custom_malloc.h"
#include "posix_lock.h"
#include "other.h"
#include "sys_alloc.h"
#include "block_header.h"

void * custom_malloc(heap_t* heap, size_t size) {
	void *ptr;
	int fixed_list_id, i, found;
	maptable_node_t *current_maptable_node;
	void *current_block, *previous_block;

	ptr = NULL;
	previous_block = NULL;

	posix_lock(heap);

	printf("Searching for a free block of size %d.\n", size);

	fixed_list_id = map_size_to_list(heap, size);
	
	// If a fixed list is found, do a first fit
	if(fixed_list_id != -1) {
		printf("Searching on fixed lists...\n");
		current_maptable_node = heap->maptable_head;
		// traverse through the maptable node list
		if(fixed_list_id != 0) {
			for(i = 1; i < fixed_list_id; i++) {
				current_maptable_node = current_maptable_node->next;
			}
		}
		if(current_maptable_node->fixed_list_head != NULL) {
			ptr = current_maptable_node->fixed_list_head;
			current_maptable_node->fixed_list_head = get_next(ptr);
			set_requested_size(ptr, size);
			set_next(ptr, heap->used_blocks_head);
		 	heap->used_blocks_head = ptr;
		}
	}

	if(ptr == NULL) {
		found = 0;

		// first fit from free list
		printf("Searching on the free list...\n", size);
		for(current_block = heap->free_list_head; current_block != NULL; current_block = get_next(current_block)) {
			if(get_size(current_block) >= size) {
				ptr = current_block;
				set_requested_size(ptr, size);
				set_next(ptr, heap->used_blocks_head);
				heap->used_blocks_head = ptr;
				if(current_block != heap->free_list_head) {
					set_next(previous_block, get_next(ptr));
				} else {
					heap->free_list_head = get_next(ptr);
				}
				posix_unlock(heap);
				printf("Block found in the free list.\n");
				return ptr;
			}
			previous_block = current_block;
		}

		if(!found) {
			printf("No free available chunk was found.\n");
			ptr = sys_alloc(heap, size);
			printf("Chuck was given by the OS.\n");
		}

	}

	posix_unlock(heap);
	return ptr;
}