char *mem_pool::mem_pool_impl::alloc_page(int &index)
{
assert(inited == 1);
if(free_pages == 0) {
return 0; /* there are no pages to allocate */
}
/*
* find a free page index from bitmap
*/
int page_index;
for(;; ++current_page) {
if(current_page == total_pages) {
current_page = 0;
}
if(TEST_BIT(page_bitmap, current_page) == 0) { /* found */
page_index = current_page++;
break;
}
}
index = page_index;
--free_pages;
SET_BIT(page_bitmap, index);
return index_to_page(index);
}
/*
* Allocate physically contiguous memory region.
* @param ord Block order (2^ord pages)
* @param zero Zero out block content if true
* @return Pointer to linear memory region
*/
void *Buddy::alloc (unsigned short ord, Fill fill)
{
Lock_guard <Spinlock> guard (lock);
for (unsigned short j = ord; j < order; j++) {
if (head[j].next == head + j)
continue;
Block *block = head[j].next;
block->prev->next = block->next;
block->next->prev = block->prev;
block->ord = ord;
block->tag = Block::Used;
while (j-- != ord) {
Block *buddy = block + (1ul << j);
buddy->prev = buddy->next = head + j;
buddy->ord = j;
buddy->tag = Block::Free;
head[j].next = head[j].prev = buddy;
}
mword virt = index_to_page (block_to_index (block));
// Ensure corresponding physical block is order-aligned
assert ((virt_to_phys (virt) & ((1ul << (block->ord + PAGE_BITS)) - 1)) == 0);
if (fill)
memset (reinterpret_cast<void *>(virt), fill == FILL_0 ? 0 : -1, 1ul << (block->ord + PAGE_BITS));
return reinterpret_cast<void *>(virt);
}
Console::panic ("Out of memory");
}
