Luna/kernel/src/memory/UserVM.h

#pragma once
#include <luna/LinkedList.h>
#include <luna/OwnedPtr.h>
#include <luna/Result.h>

class VMRegion : LinkedListNode<VMRegion>
{
  public:
    u64 start;
    u64 end;
    usize count;
    bool used { true };
    bool persistent { false };
};

class UserVM
{
  public:
    UserVM();
    ~UserVM();

    Result<u64> alloc_region(usize count, bool persistent = false);

    Result<bool> test_and_alloc_region(u64 address, usize count, bool persistent = false)
    {
        return set_region(address, count, true, persistent);
    }

    Result<bool> free_region(u64 address, usize count)
    {
        return set_region(address, count, false, false);
    }

    static Result<OwnedPtr<UserVM>> try_create();

    Result<OwnedPtr<UserVM>> clone();

  private:
    Result<bool> set_region(u64 address, usize count, bool used, bool persistent);
    Result<void> create_default_region();
    Result<void> create_null_region();
    void try_merge_region_with_neighbors(VMRegion* region);
    void merge_contiguous_regions(VMRegion* a, VMRegion* b);
    Result<VMRegion*> split_region(VMRegion* parent, u64 boundary);
    LinkedList<VMRegion> m_regions;
};