ryujinx/Ryujinx.HLE/HOS/Services/Mii/UtilityImpl.cs

using Ryujinx.Common.Utilities;
using Ryujinx.Cpu;
using Ryujinx.HLE.HOS.Services.Mii.Types;
using Ryujinx.HLE.HOS.Services.Time;
using Ryujinx.HLE.HOS.Services.Time.Clock;
using System;

namespace Ryujinx.HLE.HOS.Services.Mii
{
    class UtilityImpl
    {
        private uint _x;
        private uint _y;
        private uint _z;
        private uint _w;

        public UtilityImpl(ITickSource tickSource)
        {
            _x = 123456789;
            _y = 362436069;

            TimeSpanType time = TimeManager.Instance.TickBasedSteadyClock.GetCurrentRawTimePoint(tickSource);

            _w = (uint)(time.NanoSeconds & uint.MaxValue);
            _z = (uint)((time.NanoSeconds >> 32) & uint.MaxValue);
        }

        private uint GetRandom()
        {
            uint t = (_x ^ (_x << 11));

            _x = _y;
            _y = _z;
            _z = _w;
            _w = (_w ^ (_w >> 19)) ^ (t ^ (t >> 8));

            return _w;
        }

        public int GetRandom(int end)
        {
            return (int)GetRandom((uint)end);
        }

        public uint GetRandom(uint end)
        {
            uint random = GetRandom();

            return random - random / end * end;
        }

        public uint GetRandom(uint start, uint end)
        {
            uint random = GetRandom();

            return random - random / (1 - start + end) * (1 - start + end) + start;
        }

        public int GetRandom(int start, int end)
        {
            return (int)GetRandom((uint)start, (uint)end);
        }

        public CreateId MakeCreateId()
        {
            UInt128 value = UInt128Utils.CreateRandom();

            // Ensure the random ID generated is valid as a create id.
            value &= ~new UInt128(0xC0, 0);
            value |= new UInt128(0x80, 0);

            return new CreateId(value);
        }
    }
}