ass3_manual - ArmandasRokas/dtu_notes GitHub Wiki

How to begin with assignment 3

  1. First you need to initialize data structure that will represent the memory blocks by using memoryList. It should be done under /* TODO: Initialize memory management structur*/ in the initmem() function in the mymem.c source file. Here's how to create the first node for a double linked list and to assign it to the head:
head = (struct memoryList*) malloc(sizeof (struct memoryList));
head->last = NULL; 
head->next = NULL;
head->size = sz; // initialy the first block size is equals to the memory pool size. 
head->alloc = 0;  // not allocated
head->ptr = myMemory;  // points to the same memory adress as the memory pool
  1. Now you can begin to implement mymalloc function. In order to keep it simple you can just create a new block (a node in double linked list) next to the free block, when mymalloc function is called. Next you need to change the size of the current block to be requested size, while the size of the new block should be set to the remaining size. Lastly you should set the current block to be allocated (currBlock->alloc = 1) . Here's how the double linked list should look initially, after calling mymalloc(100) and after mymalloc(50):
null <- 500(free) -> null // Initialy there is only one head node (a block) which size is equal to the whole memory pool

null <- 100(alloc) <-> 400(free) -> null // Efter mymalloc(100) 

null <- 100(alloc) <-> 50(alloc) <-> 350(free) -> null // Efter mymalloc(50) 

//and so on.
  1. In order to debug your implementation you can run:

  • make

  • ./mem -try first (if you implementing first-fit)

  • Note : it is required that you have implemented at least print_memory(), where you should basically loop the double linked list and print the size of each node and if they are allocated or not.