void * dkbtalloc(size_t n){
/*
* The memory we search for has to include the memory control header, but
* the user of malloc doesn't need to know this, so we'll just add it in
* for them.
*/
n=n+sizeof(node_t);
node_t *p= AVAIL->nlink; /* from the free list head */
node_t * q=NULL; /* to store the block after spliting */
while(p!=NULL){
if (p->size==n){ /* exaclly the same size */
block_remove(p); /* remove p from dll */
set_block_used(p); /* mark p as allocated */
set_prev_used(get_block_pnxt(p));/* set p's next physical block */
return (void*) p; /* return block p */
}
if (p->size>n){ /* suitable block is bigger than n */
q=block_split(p,n); /* splict p, q is the new block(right part) */
set_block_free(q); /* set new left block as free */
set_prev_used(q); /* the previous of q is used */
set_block_used(p);
block_remove(p);
return (void*)p;
}
p=p->nlink; /* move step further */
}
return NULL;
}
static int recurse_helper(block_if bi, block_no b, int nlevels, int *n_blocks) {
block_t read_block;
struct ufs_state *us = bi->state;
if(*n_blocks == 0) {
return 0;
}
//Nlevels = 0, reached a data block - set it to zero
if(nlevels == 0) {
if((*us->below->write)(us->below, b, &null_block) < 0) {
return -1;
}
set_block_free(bi, b);
(*n_blocks)--;
return 0;
}
//Indirect block, read it
if((*us->below->read)(us->below, b, &read_block) < 0) {
return -1;
}
//Call the function recursively on every reference in the indirect block
int j = 0;
struct ufs_indirblock *indir = (struct ufs_indirblock *) &read_block;
while(j < REFS_PER_BLOCK) {
if(indir->refs[j] != 0)
recurse_helper(bi, indir->refs[j], nlevels - 1, n_blocks);
else
(*n_blocks)--;
j++;
}
//Set the block to 0
if((*us->below->write)(us->below, b, &null_block) < 0) {
return -1;
}
else {
set_block_free(bi, b);
}
return 0;
}
/* relase po with size N to AVAIL list */
void dkbtfree(void * x){
assert(x!=NULL);
node_t * po=x;
node_t * block;
block=block_merge_left(get_block_pprv(po), po);
block=block_merge_right(block, get_block_pnxt(block));/* return new block */
set_block_free(block);
set_prev_free(get_block_pnxt(block));
set_prev_used(block);
block_insert(block); /*insert into dll */
}
/* initially, AVAIL points to a free block */
void dkbtinit( ){
node_t * p= (node_t*) malloc((MAX_WORDS)*( sizeof(void *)));
AVAIL= (node_t* )(void*)malloc(sizeof(node_t));
AVAIL->size=sizeof(node_t);
AVAIL->nlink=p;
AVAIL->plink=NULL;
p->nlink=NULL;
p->plink=AVAIL;
p->pprv=AVAIL;
p->size=MAX_WORDS;
set_block_free(p); /* set block as free*/
// p->psize=0;
}
