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;
}
void testBlock_splitBlock(CuTest* testCase) {
cactusBlockTestSetup();
Block *leftBlock, *rightBlock;
block_split(block, 2, &leftBlock, &rightBlock);
CuAssertIntEquals(testCase, 2, block_getLength(leftBlock));
CuAssertIntEquals(testCase, 1, block_getLength(rightBlock));
CuAssertIntEquals(testCase, 3, block_getInstanceNumber(leftBlock));
CuAssertIntEquals(testCase, 3, block_getInstanceNumber(rightBlock));
Block *leftLeftBlock, *leftRightBlock;
block_split(leftBlock, 1, &leftLeftBlock, &leftRightBlock);
CuAssertIntEquals(testCase, 1, block_getLength(leftLeftBlock));
CuAssertIntEquals(testCase, 1, block_getLength(leftRightBlock));
CuAssertIntEquals(testCase, 3, block_getInstanceNumber(leftLeftBlock));
CuAssertIntEquals(testCase, 3, block_getInstanceNumber(leftRightBlock));
//doesn't currently check the instances.
cactusBlockTestTeardown();
}
void * kmalloc(size_t n)
{
list_item *cur_node;
block_info *best;
if(n == 0)
{
return NULL;
}
/* Round the size to keep blocks aligned */
n = ((KALLOC_ALIGN * n) + (KALLOC_ALIGN - 1)) / KALLOC_ALIGN;
/* Find the best fitting free block */
cur_node = &(first_block->node);
best = NULL;
while(cur_node)
{
block_info *b;
b = LIST_GET_OBJECT(cur_node, block_info, node);
if((b->state == STATE_FREE) && (usable_block_size(b) >= n))
{
if(best == NULL)
{
best = b;
}
else if(block_size(b) < block_size(best))
{
/* This one fits best */
best = b;
}
}
cur_node = cur_node->next;
}
/* Search is finished */
if(best == NULL)
{
return NULL;
}
/* We have found a block, split it to the requested size */
block_split(best, n);
/* Mark block as used and return the pointer to usable data */
best->state = STATE_USED;
return (best + 1);
}
