/**
* coalesce - boundary tag coalescing. Return ptr to coalesced block
* Removes adjacent blocks from the free list if either one or both are free.
* Merges block bp with these free adjacent blocks and inserts it onto list.
* @return - bp - pointer to the merged block
*/
static void *coalesce(void *bp){
size_t prev_alloc;
prev_alloc = GET_FALLOC(PREV_BLK(bp)) || PREV_BLK(bp) == bp;
size_t next_alloc = GET_HALLOC(NEXT_BLK(bp));
size_t size = GET_HSIZE(bp);
/* Case 1 next block is free */
if (prev_alloc && !next_alloc) {
size += GET_HSIZE(NEXT_BLK(bp));
mm_remove(NEXT_BLK(bp));
SET_HDRP(bp, PACK(size, 0));
SET_FTRP(bp, PACK(size, 0));
}/* Case 2 prev block is free */
else if (!prev_alloc && next_alloc) {
size += GET_HSIZE(PREV_BLK(bp));
bp = PREV_BLK(bp);
mm_remove(bp);
SET_HDRP(bp, PACK(size, 0));
SET_FTRP(bp, PACK(size, 0));
}/* Case 3 both blocks are free */
else if (!prev_alloc && !next_alloc) {
size += GET_HSIZE(PREV_BLK(bp)) + GET_HSIZE(NEXT_BLK(bp));
mm_remove(PREV_BLK(bp));
mm_remove(NEXT_BLK(bp));
bp = PREV_BLK(bp);
SET_HDRP(bp, PACK(size, 0));
SET_FTRP(bp, PACK(size, 0));
}/* lastly insert bp into free list and return bp */
mm_insert(bp);
return bp;
}
static void *coalesce(void *bp){
size_t previous_alloc = GET_ALLOC(FTRP(PREV_BLKP(bp))) || PREV_BLKP(bp) == bp;
size_t next__alloc = GET_ALLOC(HDRP(NEXT_BLKP(bp)));
size_t size = GET_SIZE(HDRP(bp));
if(previous_alloc && !next__alloc){
size += GET_SIZE(HDRP(NEXT_BLKP(bp)));
mm_remove(NEXT_BLKP(bp));
PUT(HDRP(bp), PACK(size, 0));
PUT(FTRP(bp), PACK(size, 0));
}
else if(!previous_alloc && next__alloc){
size += GET_SIZE(HDRP(PREV_BLKP(bp)));
bp = PREV_BLKP(bp);
mm_remove(bp);
PUT(HDRP(bp), PACK(size, 0));
PUT(FTRP(bp), PACK(size, 0));
}
else if(!previous_alloc && !next__alloc){
size += GET_SIZE(HDRP(PREV_BLKP(bp))) + GET_SIZE(HDRP(NEXT_BLKP(bp)));
mm_remove(PREV_BLKP(bp));
mm_remove(NEXT_BLKP(bp));
bp = PREV_BLKP(bp);
PUT(HDRP(bp), PACK(size, 0));
PUT(FTRP(bp), PACK(size, 0));
}
mm_insert(bp);
return bp;
}
/* $begin mmfree */
static void *coalesce(void *bp)
{
size_t prev_alloc = GET_ALLOC(FTRP(PREV_BLKP(bp)));
size_t next_alloc = GET_ALLOC(HDRP(NEXT_BLKP(bp)));
size_t size = GET_SIZE(HDRP(bp));
if (prev_alloc && next_alloc) { /* Case 1: Neighbors both allocated */
return bp;
}
else if (prev_alloc && !next_alloc) { /* Case 2: Only the previous is allocated*/
size += GET_SIZE(HDRP(NEXT_BLKP(bp)));
/* If only the previous block is allocated, remove the next block */
tree_root = mm_remove(tree_root, NEXT_BLKP(bp));
PUT(HDRP(bp), PACK(size, 0));
PUT(FTRP(bp), PACK(size,0));
return(bp);
}
else if (!prev_alloc && next_alloc) { /* Case 3: Only the next is allocated */
size += GET_SIZE(HDRP(PREV_BLKP(bp)));
/* If only the next block is allocated, remove the previous block */
tree_root = mm_remove(tree_root, PREV_BLKP(bp));
PUT(FTRP(bp), PACK(size, 0));
PUT(HDRP(PREV_BLKP(bp)), PACK(size, 0));
return(PREV_BLKP(bp));
}
else { /* Case 4: Neither are allocated */
size += GET_SIZE(HDRP(PREV_BLKP(bp))) +
GET_SIZE(FTRP(NEXT_BLKP(bp)));
/* If neither blocks are allocated, remove them both */
tree_root = mm_remove(tree_root, NEXT_BLKP(bp));
tree_root = mm_remove(tree_root, PREV_BLKP(bp));
PUT(HDRP(PREV_BLKP(bp)), PACK(size, 0));
PUT(FTRP(NEXT_BLKP(bp)), PACK(size, 0));
return(PREV_BLKP(bp));
}
}
/*
* mm_remove_children - Remove the node from the Binary Tree as long as it has two children
*/
void *mm_remove_children(void *root, void *bp)
{
void *parent_node = mm_parent(root, bp);
void *replacement = mm_replace(LEFT(bp));
void *new_bp;
/* Remove the replacement and store the new bp */
new_bp = mm_remove(LEFT(bp), replacement);
SETLEFT(replacement, new_bp);
SETRIGHT(replacement, RIGHT(bp));
if(parent_node != NULL)
{
if(LEFT(parent_node) == bp)
SETLEFT(parent_node, replacement);
else
SETRIGHT(parent_node, replacement);
return root;
}
else
{
return replacement;
}
}
/* $begin mmmalloc */
void *mm_malloc(size_t size)
{
size_t asize; /* adjusted block size */
size_t extendsize; /* amount to extend heap if no fit */
char *bp;
/* Ignore spurious requests */
if (size <= 0)
return NULL;
/* Adjust block size to include overhead and alignment reqs. */
if (size <= DSIZE)
asize = DSIZE + OVERHEAD;
else
asize = DSIZE * ((size + (OVERHEAD) + (DSIZE-1)) / DSIZE);
/* Search the free list for a fit */
if ((bp = mm_ceiling(tree_root,asize)) != NULL)
{
tree_root = mm_remove(tree_root,bp);
bp = place(bp, asize);
return bp;
}
/* No fit found. Get more memory and place the block */
extendsize = MAX(asize,CHUNKSIZE);
if ((bp = extend_heap(extendsize/WSIZE)) == NULL)
return NULL;
bp = place(bp, asize);
return bp;
}
/**
* Place block of asize bytes at start of free block bp
* and split if remainder would be at least minimum block size
* @param - bp - pointer to a free block, not on the tree of free blocks
* @param - asize - the requested size of free block
*/
static void place(void *bp, size_t asize){
size_t csize = GET_HSIZE(bp);
if ((csize - asize) >= BLKSIZE) {
SET_HDRP(bp, PACK(asize, 1));
SET_FTRP(bp, PACK(asize, 1));
mm_remove(bp);
bp = NEXT_BLK(bp);
SET_HDRP(bp, PACK(csize-asize, 0));
SET_FTRP(bp, PACK(csize-asize, 0));
coalesce(bp);
}
else {
SET_HDRP(bp, PACK(csize, 1));
SET_FTRP(bp, PACK(csize, 1));
mm_remove(bp);
}
}
static void place(void *bp, size_t size){
size_t totalsize = GET_SIZE(HDRP(bp));
if((totalsize - size) >= OVERHEAD){
PUT(HDRP(bp), PACK(size, 1));
PUT(FTRP(bp), PACK(size, 1));
mm_remove(bp);
bp = NEXT_BLKP(bp);
PUT(HDRP(bp), PACK(totalsize - size, 0));
PUT(FTRP(bp), PACK(totalsize - size, 0));
coalesce(bp);
}
else{
PUT(HDRP(bp), PACK(totalsize, 1));
PUT(FTRP(bp), PACK(totalsize, 1));
mm_remove(bp);
}
}
/**
* Return a block of size >= newsize
* that preserves all the data from the
* payload of the block bp.
* @param - a pointer to an allocated block
* @param - size - a new size requested
* @return - pointer to a block size >= newsize
*/
void *mm_realloc(void *bp, size_t size){
if(size <= 0){
mm_free(bp);
return NULL;
}else if(bp == NULL){
bp = mm_malloc(size);
return bp;
}
if(size > 0){
size_t currentsize = GET_HSIZE(bp);
size_t newsize = ALIGN(size + OVERHEAD);
/* newsize is less than currentsize just return bp */
if(newsize <= currentsize){
return bp;
} /* newsize is greater than currentsize */
else {
size_t next_alloc = GET_HALLOC(NEXT_BLK(bp));
size_t csize;
size_t asize;
/* next block is free and the size of the two blocks is greater than or equal the new size */
if(!next_alloc && ((csize = currentsize + GET_HSIZE(NEXT_BLK(bp)))) >= newsize){
mm_remove(NEXT_BLK(bp));
SET_HDRP(bp, PACK(csize, 1));
SET_FTRP(bp, PACK(csize, 1));
return bp;
} /* next block is free and the block is the last block before the epilogue */
else if(!next_alloc && ((GET_HSIZE(NEXT_BLK(NEXT_BLK(bp)))) == 0)){
csize = newsize - currentsize + GET_HSIZE(NEXT_BLK(bp));
void *temp = extend_heap(csize);
asize = currentsize + GET_HSIZE(temp);
SET_HDRP(bp, PACK(asize, 1));
SET_FTRP(bp, PACK(asize, 1));
return bp;
} /* if bp is the last block before epilogue */
else if(GET_HSIZE(NEXT_BLK(bp)) == 0){
csize = newsize - currentsize;
void *temp = extend_heap(csize);
asize = currentsize + GET_HSIZE(temp);
SET_HDRP(bp, PACK(asize, 1));
SET_FTRP(bp, PACK(asize, 1));
return bp;
} /* last ditch attemp try to extend heap for additional size */
else {
void *newbp = mm_malloc(newsize);
place(newbp, newsize);
memcpy(newbp, bp, newsize);
mm_free(bp);
return newbp;
}
} /* return NULL */
}else{
return NULL;
}
}
/* Not implemented. For consistency with 15-213 malloc driver */
void *mm_realloc(void *ptr, size_t size)
{
void *bp;
size_t asize = ADJUSTSIZE(size);
if(!GETSIZE(NEXT_BLKP(ptr)))
{
size_t extendsize = MAX(asize, CHUNKSIZE);
bp = extend_heap(extendsize/4);
size_t nsize = extendsize + GETSIZE(ptr) - asize;
PUT(HDRP(ptr), PACK(asize,1));
PUT(FTRP(ptr), PACK(asize,1));
void *blk = NEXT_BLKP(ptr);
PUT(HDRP(blk), PACK(nsize,0));
PUT(FTRP(blk), PACK(nsize, 0));
tree_root = mm_insert(tree_root, blk);
return ptr;
}
if(!(GET_ALLOC(HDRP(NEXT_BLKP(ptr)))))
{
bp = NEXT_BLKP(ptr);
size_t total = GETSIZE(ptr) + GETSIZE(bp);
if(total >= asize)
{
size_t nsize = total - asize;
tree_root = mm_remove(tree_root,bp);
if(nsize < 16)
{
PUT(HDRP(ptr), PACK(total, 1));
PUT(FTRP(ptr), PACK(total, 1));
return ptr;
}
else
{
PUT(HDRP(ptr), PACK(asize, 1));
PUT(FTRP(ptr), PACK(asize, 1));
void *blk = NEXT_BLKP(ptr);
PUT(HDRP(blk), PACK(nsize,0));
PUT(FTRP(blk), PACK(nsize,0));
tree_root = mm_insert(tree_root, blk);
return ptr;
}
}
else if(!GETSIZE(NEXT_BLKP(bp)))
{
size_t extendsize = MAX(asize, CHUNKSIZE);
extend_heap(extendsize/4);
size_t nsize = extendsize + total - asize;
PUT(HDRP(ptr), PACK(asize,1));
PUT(FTRP(ptr), PACK(asize,1));
void *blk = NEXT_BLKP(ptr);
PUT(HDRP(blk), PACK(nsize,0));
PUT(FTRP(blk), PACK(nsize,0));
tree_root = mm_insert(tree_root, blk);
return ptr;
}
}
bp = mm_malloc(size);
memcpy(bp, ptr, (GETSIZE(ptr) - DSIZE));
mm_free(ptr);
return bp;
}