/*
* mm_insert - Insert a free block into the Binary Tree and return bp
*/
void *mm_insert(void *root, void* bp)
{
/* Determine if the tree is empty and initiate all nodes to NULL */
if(root == NULL)
{
SETLEFT(bp, NULL);
SETRIGHT(bp, NULL);
return bp;
}
else if(GETSIZE(bp) <= GETSIZE(root))
{
SETLEFT(root, mm_insert(LEFT(root),bp));
return root;
}
else if(GETSIZE(bp) > GETSIZE(root))
{
SETRIGHT(root, mm_insert(RIGHT(root),bp));
return root;
}
/* If there's an error, return -1 */
return -1;
}
/* $begin mminit */
int mm_init(void)
{
void *bp;
tree_root = NULL;
/* Create the initial empty heap */
if ((heap_listp = mem_sbrk(PROLOGSIZE)) == NULL)
return -1;
PUT(heap_listp, 0); /* alignment padding */
PUT(heap_listp+WSIZE, PACK(OVERHEAD, 1)); /* prologue header */
PUT(heap_listp+DSIZE, PACK(OVERHEAD, 1)); /* prologue footer */
PUT(heap_listp+WSIZE+DSIZE, PACK(0, 1)); /* epilogue header */
heap_listp += DSIZE;
/* Extend the empty heap with a free block of CHUNKSIZE bytes */
bp = extend_heap(CHUNKSIZE/WSIZE);
if (bp == NULL)
return -1;
tree_root = mm_insert(tree_root, bp);
return 0;
}
/**
* 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 */
void mm_free(void *bp)
{
size_t size = GET_SIZE(HDRP(bp));
PUT(HDRP(bp), PACK(size, 0));
PUT(FTRP(bp), PACK(size, 0));
tree_root = mm_insert(tree_root,coalesce(bp));
}
/* $begin mmplace-proto */
static void *place(void *bp, size_t asize)
/* $end mmplace-proto */
{
size_t csize = GET_SIZE(HDRP(bp));
size_t split_size = (csize - asize);
if (split_size >= (DSIZE + OVERHEAD)) {
size_t avg = (GETSIZE(NEXT_BLKP(bp)) + GETSIZE(PREV_BLKP(bp)))/2;
void* large;
void* small;
int split_side;
/* Which side should we split on? Let split_side = 0 or 1
0 = Let's split the end
1 = Let's split the front
*/
if(GETSIZE(NEXT_BLKP(bp)) > GETSIZE(PREV_BLKP(bp)))
{
large = NEXT_BLKP(bp);
small = PREV_BLKP(bp);
}
else
{
large = PREV_BLKP(bp);
small = NEXT_BLKP(bp);
}
if(asize > avg)
{
if(PREV_BLKP(bp) == large)
split_side = 0;
else
split_side = 1;
}
else
{
if(PREV_BLKP(bp) == large)
split_side = 1;
else
split_side = 0;
}
if(split_side != 1)
{
PUT(HDRP(bp), PACK(asize, 1));
PUT(FTRP(bp), PACK(asize, 1));
void* split = NEXT_BLKP(bp);
PUT(HDRP(split), PACK(csize-asize, 0));
PUT(FTRP(split), PACK(csize-asize, 0));
tree_root = mm_insert(tree_root,split);
return bp;
}
else
{
PUT(HDRP(bp), PACK(split_size,0));
PUT(FTRP(bp), PACK(split_size,0));
void *blk = NEXT_BLKP(bp);
PUT(HDRP(blk), PACK(asize, 1));
PUT(FTRP(blk), PACK(asize, 1));
tree_root = mm_insert(tree_root,bp);
return blk;
}
}
else
{
PUT(HDRP(bp), PACK(csize, 1));
PUT(FTRP(bp), PACK(csize, 1));
return bp;
}
}
/* 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;
}