#pragma once
/// \file page_tree.h
/// Definition of mapped page tracking structure and related definitions

#include <stdint.h>

/// A radix tree node that tracks mapped pages
class page_tree
{
public:
	/// Get the physical address of the page at the given offset.
	/// \arg root    The root node of the tree
	/// \arg offset  Offset into the VMA, in bytes
	/// \arg page    [out] Receives the page physical address, if found
	/// \returns     True if a page was found
	static bool find(const page_tree *root, uint64_t offset, uintptr_t &page);

	/// Get the physical address of the page at the given offset. If one does
	/// not exist yet, allocate a page, insert it, and return that.
	/// \arg root    [inout] The root node of the tree. This pointer may be updated.
	/// \arg offset  Offset into the VMA, in bytes
	/// \arg page    [out] Receives the page physical address, if found
	/// \returns     True if a page was found
	static bool find_or_add(page_tree * &root, uint64_t offset, uintptr_t &page);

private:
	page_tree(uint64_t base, uint8_t level);

	/// Stores the page offset of the start of this node's pages in bits 0:41
	/// and the depth of tree this node represents in bits 42:44 (0-7)
	uint64_t m_base;

	/// For a level 0 node, the entries area all physical page addresses.
	/// Other nodes contain pointers to child tree nodes.
	union {
		uintptr_t entry;
		page_tree *child;
	} m_entries[64];
};