using System;

namespace VMdemo.Simulation
{
    [Serializable]
    public readonly struct PageTableEntry
    {
        public PageTableEntry(ulong pfn, bool present, bool dirty = false)
        {
            Pfn = pfn;
            Present = present;
            Dirty = dirty;
        }

        public ulong Pfn { get; }
        public bool Present { get; }
        public bool Dirty { get; }

        public static PageTableEntry NotPresent => new PageTableEntry(0UL, false, false);

        public PageTableEntry MarkPresent(ulong pfn, bool dirty = false)
        {
            return new PageTableEntry(pfn, true, dirty);
        }

        public PageTableEntry MarkNotPresent()
        {
            return new PageTableEntry(Pfn, false, Dirty);
        }

        public override string ToString()
        {
            return $"PFN={Pfn}, Present={Present}, Dirty={Dirty}";
        }
    }
}