Method alloc_fromrgn

src/allocator/lnls.rs:104–125

Attempt to allocate using a specific region, with a specifc size and alignment:

(region: &ListNode, size: usize, align: usize)

	// Attempt to allocate using a specific region, with a specifc size and alignment:
	fn alloc_fromrgn(region: &ListNode, size: usize, align: usize) -> Result<usize, ()>
	{
		let alloc_start = alignup(region.addr_start(), align);
		let alloc_end = alloc_start.checked_add(size).ok_or(())?;

		if alloc_end > region.addr_end()
		{
			// If memory region is too small:
			return Err(());
		}

		let excess_size = region.addr_end() - alloc_end;

		if excess_size > 0 && excess_size < mem::size_of::<ListNode>()
		{
			// If the remaining region is insufficient in size to hold a ListNode:
			return Err(());
		}

		// If memory region is viable for allocation:
		Ok(alloc_start)
	}

	// Modify specified layout so that the allocated memory region can also hold a ListNode:
	// NOTE: This will return a tuple, consisting of the adjusted size, and the alignment (size, align).