int main()
{
struct Node * tempNode1, *tempNode2, *tempNode3;
int size = 10;
struct HeadNode * tempHead = buddy_new(size);
if (tempHead!=NULL)
{
//注意申请的空间最大不是2^k, 而是2^k - 1
tempNode1 = buddy_alloc(tempHead,size,511);
buddy_print(tempHead, size);
tempNode2 = buddy_alloc(tempHead,size,10);
buddy_print(tempHead, size);
tempNode3 = buddy_alloc(tempHead,size,10);
buddy_print(tempHead, size);
buddy_combine(tempHead, size, tempNode3);
buddy_print(tempHead, size);
buddy_combine(tempHead, size, tempNode2);
buddy_print(tempHead, size);
buddy_combine(tempHead, size, tempNode1);
buddy_print(tempHead, size);
}
buddy_free(tempHead);
getchar();
return 0;
}
int pfree(ulong pfn)
{
// Obtain the node
struct palloc_node *node = get_node_by_pfn(pfn);
// Get tag and order
int tag = node->tag;
int order = node->order;
int order_count = 0x1 << order;
// Setup the node
node->alloc = 0;
// Lock the bucket
spin_lock_int(&buckets[tag].lock);
// Insert the node back to the list
if (buckets[tag].buddies[order].value) {
node->next = buckets[tag].buddies[order].next;
node->has_next = 1;
} else {
node->next = 0;
node->has_next = 0;
}
buckets[tag].buddies[order].has_next = 1;
buckets[tag].buddies[order].next = pfn;
// Setup the bucket
buckets[tag].avail_pages += order_count;
// Combine the buddy system
buddy_combine(pfn);
// Unlock the bucket
spin_unlock_int(&buckets[tag].lock);
return order_count;
}
static void buddy_combine(ulong pfn)
{
// Obtain the node
struct palloc_node *node = get_node_by_pfn(pfn);
int tag = node->tag;
int order = node->order;
int order_count = 0x1 << order;
// If we already have the highest order, then we are done
if (order == PALLOC_MAX_ORDER) {
return;
}
// Get some info of the higher order
int higher = order + 1;
ulong higher_size = ((ulong)0x1 << higher) * PAGE_SIZE;
ulong higher_pfn = 0;
ulong other_pfn = 0;
ulong cur_addr = PFN_TO_ADDR(pfn);
// Check the other node to see if they can form a buddy
if (0 == cur_addr % higher_size) {
higher_pfn = pfn;
other_pfn = pfn + order_count;
} else {
higher_pfn = pfn - order_count;
other_pfn = pfn - order_count;
}
struct palloc_node *other_node = get_node_by_pfn(other_pfn);
// If the other node doesn't belong to the same bucket as current node,
// or the other node is in use, then we are done, there's no way to combine
if (
!other_node || !other_node->avail || other_node->tag != tag ||
other_node->alloc || order != other_node->order
) {
return;
}
// Remove both nodes from the list
remove_node(pfn, tag, order);
remove_node(other_pfn, tag, order);
// Setup the two nodes
node->has_next = 0;
node->next = 0;
node->order = higher;
node->tag = tag;
node->avail = 1;
other_node->has_next = 0;
other_node->next = 0;
other_node->order = higher;
other_node->tag = tag;
other_node->avail = 1;
// Insert them into the higher order list
insert_node(higher_pfn, tag, higher);
// Combine the higiher order
buddy_combine(higher_pfn);
}
