static void FL_remove(char *bp)
//remove block from free list given free block bp
{
ASSERT(bp != NULL) ;
ASSERT(GETALLOC(bp) == 0) ;
ASSERT(bp != epilogue && bp != prologue && bp != heapStart) ;
if(bp == NULL) return ;
else if(DEREF_NEXT(bp) == 0 && DEREF_PREV(bp) == 0) {
// if list has only 1 element make list empty
firstFBP = NULL ;
return ;
}
char *next_bp = GET_NEXT(bp) ;
char *prev_bp = GET_PREV(bp) ;
if(next_bp == heapStart && prev_bp == heapStart) {
firstFBP = NULL ; // empty free list
return ;
}
else if(next_bp == heapStart) { //prev_bp != heapStart
SET_NEXT(prev_bp, 0) ; //if bp is end node in free list next->prev = 0
return ;
}
else if (prev_bp == heapStart) {
SET_PREV(next_bp, 0) ; // if bp is start node, next->prev = 0
firstFBP = next_bp ; // change firstFBP to point to new bp
ASSERT(DEREF_PREV(firstFBP) == 0) ;
return ;
}
// normal case
SET_PREV(next_bp, DEREF_PREV(bp)) ;
SET_NEXT(prev_bp, DEREF_NEXT(bp)) ; // prev->next = curr->next
return ;
}
/*
* place block
*/
void *place(void *bp, size_t size){
void *free_bp;
size_t full_size = GET_SIZE(bp); //size of the free block before place
/* not split the free block for small allocation or small space left */
if ((full_size - size) < FSIZE || size < FSIZE ){
/* reset hdr/ftr the alloc bit */
PUT(HDRP(bp), PACK(full_size, 1));
PUT(FTRP(bp), PACK(full_size, 1));
/* delete from free list */
SET_NEXT(GET_PREV(bp), GET_NEXT(bp));
SET_PREV(GET_NEXT(bp), GET_PREV(bp));
return bp;
}
/* after alloc size bytes,
* the original free block still have bytes in the tail,
* split the free block into two parts: |alloc one|free one| */
free_bp = bp + size;
/* reset ftr/hdr of the new free block*/
PUT(HDRP(free_bp), PACK(full_size-size, 0));
PUT(FTRP(free_bp), PACK(full_size-size, 0));
/* add it to free list, also delete the original free block from list */
SET_NEXT(free_bp, GET_NEXT(bp));
SET_PREV(free_bp, GET_PREV(bp));
SET_NEXT(GET_PREV(bp), free_bp);
SET_PREV(GET_NEXT(bp), free_bp);
/* set hdr/ftr of alloc block */
PUT(HDRP(bp), PACK(size, 1));
PUT(FTRP(bp), PACK(size, 1));
return bp;
}
static void FL_insert(char *bp)
//insert at start of free list
{
ASSERT(bp != NULL) ;
ASSERT(GETALLOC(HDRP(bp)) == 0) ;
ASSERT(isValidBlock(bp)) ;
if(firstFBP == NULL) {
// free list is empty
firstFBP = bp ;
SET_PREV(bp, 0) ;
SET_NEXT(bp, 0) ;
return ;
}
else {
unsigned int offset = firstFBP - heapStart ;
SET_NEXT(bp, offset) ; //bp->next = firstFBP
offset = (unsigned int)(bp - heapStart) ;
// ASSERT(DEREF_PREV(firstFBP) == 0) ;
SET_PREV(firstFBP, offset) ; // firstFBP->prev = bp
//ASSERT(DEREF_PREV(firstFBP) == offset) ;
SET_PREV(bp, 0) ; //bp->prev = NULL
firstFBP = bp ; //set bp as start of list
return ;
}
return ;
}
/* remove a link from the list `list' */
extern t_list * removeElementLink(t_list *list, t_list *element)
{
t_list *current_elem;
/* preconditions */
if (list == NULL || element == NULL)
return list;
if ((LPREV(element) == NULL) && (element != list))
return list;
/* intialize the value of `current_elem' */
current_elem = list;
while( (LDATA(current_elem) != LDATA(element))
|| (LPREV(current_elem) != LPREV(element))
|| (LNEXT(current_elem) != LNEXT(element)) )
{
/* retrieve the next element from the list */
current_elem = LNEXT(current_elem);
/* test if we reached the end of the list */
if (current_elem == NULL)
return list;
}
if (LPREV(element) == NULL)
{
assert(list == element);
if (LNEXT(element) != NULL)
{
list = LNEXT(element);
SET_PREV(LNEXT(element), NULL);
}
else
list = NULL;
/* remove the allocated memory of element */
_FREE_FUNCTION(element);
return list;
}
/* we found the element */
if (LPREV(element) != NULL)
{
/* we found the element, and it is the top of the list */
SET_NEXT(LPREV(element), LNEXT(element));
}
if (LNEXT(element) != NULL)
SET_PREV(LNEXT(element), LPREV(element));
/* remove the allocated memory of element */
_FREE_FUNCTION(element);
/* return the new top of the list */
return list;
}
static void add_free(void *bp)
{
//printf("%d %p %p\n", asize, hp, *hp);
if(free_listp) SET_PREV(free_listp, bp);
SET_PREV(bp, 0);
SET_NEXT(bp, free_listp);
free_listp = bp;
}
/**
* Adds this block to the free list of
* free blocks.
* @param - bp - pointer to a block that is already marked free.
*/
static void mm_insert(void *bp){
/* set bp next to listp */
SET_NEXT(bp, listp);
/* set prev listp to bp */
SET_PREV(listp, bp);
/* set prev bp to NULL */
SET_PREV(bp, NULL);
/* set start of list to bp */
listp = bp;
}
void LLadd(char *bp)
{
char *head = free_list;
SET_NEXT(bp, head);
SET_PREV(bp, NULL);
if(head != NULL)
{
SET_PREV(head, bp);
}
free_list = bp;
}
/*
* realloc
* if realloc size is larger than old one: malloc new space and copy
* if realloc size is smaller: shrink the block,
* and release the space as a free block
*/
void *realloc(void *oldptr, size_t size) {
size_t asize;
size_t oldsize;
void *newptr;
void *free_bp;
/* If size == 0 then this is just free, and we return NULL. */
if(size == 0) {
free(oldptr);
return 0;
}
/* If oldptr is NULL, then this is just malloc. */
if(oldptr == NULL) {
return malloc(size);
}
asize = ALIGN(size + 2*WSIZE);
oldsize = GET_SIZE(oldptr);
if (oldsize < asize){
/* if realloc size is larger than old one: malloc new space and copy*/
newptr = malloc(size);
memcpy(newptr, oldptr, oldsize - 2*WSIZE);
free(oldptr);
return newptr;
}else if (oldsize > asize){
/* realloc a smaller space */
if ((oldsize - asize) < FSIZE || asize < FSIZE ){
/* no changes */
return oldptr;
}else{
free_bp = oldptr + asize;
/* set alloc bit to 0*/
PUT(HDRP(free_bp), PACK(oldsize-asize, 0));
PUT(FTRP(free_bp), PACK(oldsize-asize, 0));
/* add to free list */
SET_NEXT(free_bp, GET_NEXT(free_listp));
SET_PREV(free_bp, free_listp);
SET_NEXT(free_listp, free_bp);
SET_PREV(GET_NEXT(free_bp), free_bp);
/* change the alloced block size to new size*/
PUT(HDRP(oldptr), PACK(asize, 1));
PUT(FTRP(oldptr), PACK(asize, 1));
return oldptr;
}
}else{
/* same size, no changes */
return oldptr;
}
}
/* remove an element from the list */
t_list * removeElement(t_list *list, void * data)
{
t_list *current_elem;
/* preconditions: the list shouldn't be empty */
if (list == NULL)
return NULL;
/* intialize the value of `current_elem' */
current_elem = list;
while ( (current_elem != NULL)
&& (LDATA(current_elem) != data))
{
current_elem = LNEXT(current_elem);
}
/* the value hasn't been found */
if (current_elem == NULL)
return list;
/* the value is found */
if (LPREV(current_elem) != NULL)
{
SET_NEXT(LPREV(current_elem), LNEXT(current_elem));
if (LNEXT(current_elem) != NULL)
SET_PREV(LNEXT(current_elem), LPREV(current_elem));
_FREE_FUNCTION(current_elem);
}
else
{
/* check the preconditions */
assert(list == current_elem);
if (LNEXT(current_elem) != NULL)
{
SET_PREV(LNEXT(current_elem), NULL);
/* update the new head of the list */
list = LNEXT(current_elem);
}
else
list = NULL;
_FREE_FUNCTION(current_elem);
}
/* postconditions: return the new head of the list */
return list;
}
/*
* free
* free a block and add it the the free list, then coalesce
*/
void free (void *ptr) {
size_t size;
if (ptr == NULL)return;
size = GET_SIZE(ptr);
/* reset hdr/ftr of alloc bit */
PUT(HDRP(ptr), PACK(size, 0));
PUT(FTRP(ptr), PACK(size, 0));
/* add to free list */
SET_NEXT(ptr, GET_NEXT(free_listp));
SET_PREV(ptr, free_listp);
SET_PREV(GET_NEXT(ptr), ptr);
SET_NEXT(free_listp, ptr);
coalesce(ptr);
}
static void rm_free(void *bp)
{
//bp->prev->next = bp->next;
//bp->next->prev = bp->prev;
size_t *prev = GET_PREV(bp);
size_t *next = GET_NEXT(bp);
if(prev) SET_NEXT(prev, next);
else free_listp = next;
if(next) SET_PREV(next, prev);
}
/**
* Removes this block from the list of
* free blocks.
* @param - bp - pointer to a block that is on the list of free blocks.
*/
static void mm_remove(void *bp){
/* if prev bp, then set it's next to bp next */
if (PREV_PTR(bp)){
SET_NEXT(PREV_PTR(bp), NEXT_PTR(bp));
}
else{ /* set listp to bp's next */
listp = NEXT_PTR(bp);
}
/* set prev of next after bp to prev of bp */
SET_PREV(NEXT_PTR(bp), PREV_PTR(bp));
}
void LLrem(char *bp)
{
unsigned int next = GET_NEXT(bp);
unsigned int prev = GET_PREV(bp);
if(prev == 0)// bp is head of list
{
free_list = (char *) next;
if(next != 0)
{
SET_PREV((char *)next, NULL);
}
}
else
{
SET_NEXT((char *) prev, next);
if(next != 0)
{
SET_PREV((char *) next, prev);
}
}
}
/*
* coalesce next block with current block
* this method only called by coalesce,
* pre-condistion is bp block is free and its next block in heap is free too,
* so we merge them
*/
void coalesce_next(void *bp){
size_t size = GET_SIZE(bp);
void *next_bp = NEXT_BLKP(bp);
/* delete next_bp from free list */
SET_NEXT(GET_PREV(next_bp), GET_NEXT(next_bp));
SET_PREV(GET_NEXT(next_bp), GET_PREV(next_bp));
/* reset hdr/ftr of the new free block */
size += GET_SIZE(NEXT_BLKP(bp));
PUT(HDRP(bp), PACK(size, 0));
PUT(FTRP(bp), PACK(size, 0));
}
/*
* extend heap
* call mem_sbrk to get a free block
* put the block into free list
*/
void *extend_heap(size_t words){
void *bp;
size_t size;
size = words*WSIZE;
if((bp = mem_sbrk(size)) == (void *)-1) return NULL;
/* initialize free block hdr/ftr */
PUT(HDRP(bp), PACK(size, 0)); //Free block hdr
PUT(FTRP(bp), PACK(size, 0)); //Free block ftr
/* put it in the free list */
SET_NEXT(bp, GET_NEXT(free_listp));
SET_PREV(bp, free_listp);
SET_NEXT(free_listp, bp);
SET_PREV(GET_NEXT(bp), bp);
/* re-init epilogue hdr */
PUT(HDRP(NEXT_BLKP(bp)), PACK(0, 1));
/* coalesce free blocks */
return coalesce(bp);
}
/* remove the first element of the list. Returns the new
* head of the list */
t_list * removeFirst(t_list *list)
{
t_list *first_elem;
if (list == NULL)
return NULL;
first_elem = list;
list = LNEXT(list);
if (list != NULL)
SET_PREV(list, NULL);
_FREE_FUNCTION(first_elem);
/* postconditions: return the new head of the list */
return list;
}
/* add an element at the beginning of the list */
t_list * addFirst(t_list *list, void * data)
{
t_list *result;
/* initialize the value of `result' */
result = newElement(data);
if (list == NULL)
return result;
/* postconditions */
SET_PREV(list, result);
SET_NEXT(result, list);
/* return the new head of the list */
return result;
}
t_list * newElement(void *data)
{
t_list * result;
/* create an instance of t_list in memory */
result = (t_list *) _ALLOC_FUNCTION(sizeof(t_list));
/* verify the out of memory condition */
if (result == NULL)
{
fprintf(stderr, "COLLECTIONS.C:: _ALLOC_FUNCTION returned a NULL pointer \n");
abort();
}
/* set the internal value of the just created t_list element */
SET_DATA(result, data);
SET_PREV(result, NULL);
SET_NEXT(result, NULL);
/* postconditions : return the element */
return result;
}
/*
* * mm_init - Initialize the memory manager
* */
int mm_init(void)
{
/* Create the initial empty heap */
if ((heap_listp = mem_sbrk(5*DSIZE)) == (void *)-1)
return -1;
heap_bot = mem_heap_lo();
PUT(heap_listp, 0); /* Alignment padding */
/* Adds Prologue footer and header */
PUT_HD_FT(heap_listp + (DSIZE), 2*DSIZE, 1);
PUT_HD_FT(heap_listp + (3*DSIZE), 2*DSIZE, 1);
PUT(heap_listp + (9 *WSIZE), PACK(0,1));
//initialization pointers for explicit list
*(int *) (heap_listp + (3*DSIZE)) = -1;
SET_NEXT(heap_listp + (3*DSIZE), heap_listp + (DSIZE));
SET_PREV(heap_listp +(DSIZE), heap_listp + (3*DSIZE));
*(int *) (heap_listp + (DSIZE) + WSIZE) = -1;
heap_listp += (3*DSIZE);
/* Extend the empty heap*/
if(extend_heap(WSIZE + 2) == NULL)
return -1;
return 0;
}
/* add an element `data' to the list `list' at position `pos'. If pos is negative
* , or is larger than the number of elements in the list, the new element is
* added on to the end of the list. Function `addElement' returns a pointer
* to the new head of the list */
t_list * addElement(t_list *list, void * data, int pos)
{
t_list *result;
t_list *current_elem;
t_list *last_elem;
int current_pos;
/* initialize the value of `result' */
result = newElement(data);
if (list == NULL)
return result;
if (pos == 0)
{
/* update the control informations */
SET_NEXT(result, list);
SET_PREV(list, result);
/* return the new head of the list */
return result;
}
/* retrieve the last element of the list */
last_elem = getLastElement(list);
assert(last_elem != NULL);
if (pos < 0)
{
/* update the control informations */
SET_NEXT(last_elem, result);
SET_PREV(result, last_elem);
/* update the value of result */
return list;
}
/* `pos' is a positive integer */
current_pos = 0;
current_elem = list;
while(current_pos < pos)
{
if (current_elem == last_elem)
{
/* update the control informations */
SET_NEXT(last_elem, result);
SET_PREV(result, last_elem);
/* update the value of result */
return list;
}
/* update the loop informations */
current_elem = LNEXT(current_elem);
current_pos++;
}
/* assertions */
assert(current_elem != NULL);
/* update the control informations */
SET_NEXT(result, current_elem);
SET_PREV(result, LPREV(current_elem));
SET_NEXT(LPREV(current_elem), result);
SET_PREV(current_elem, result);
/* return the new head of the list */
return list;
}