// This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0.
// If a copy of the MPL was not distributed with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
// Copyright (C) LibreHardwareMonitor and Contributors.
// All Rights Reserved.

using System.Runtime.InteropServices;

// ReSharper disable InconsistentNaming

namespace LibreHardwareMonitor.Interop;

internal class NtDll
{
    private const string DllName = "ntdll.dll";

    [StructLayout(LayoutKind.Sequential)]
    internal struct SYSTEM_PROCESSOR_PERFORMANCE_INFORMATION
    {
        public long IdleTime;
        public long KernelTime;
        public long UserTime;
        public long DpcTime;
        public long InterruptTime;
        public uint InterruptCount;
    }

    [StructLayout(LayoutKind.Sequential)]
    internal struct SYSTEM_PROCESSOR_IDLE_INFORMATION
    {
        public long IdleTime;
        public long C1Time;
        public long C2Time;
        public long C3Time;
        public uint C1Transitions;
        public uint C2Transitions;
        public uint C3Transitions;
        public uint Padding;
    }

    internal enum SYSTEM_INFORMATION_CLASS
    {
        SystemProcessorPerformanceInformation = 8,
        SystemProcessorIdleInformation = 42
    }

    [DllImport(DllName)]
    [DefaultDllImportSearchPaths(DllImportSearchPath.System32)]
    internal static extern int NtQuerySystemInformation(SYSTEM_INFORMATION_CLASS SystemInformationClass, [Out] SYSTEM_PROCESSOR_PERFORMANCE_INFORMATION[] SystemInformation, int SystemInformationLength, out int ReturnLength);

    [DllImport(DllName)]
    [DefaultDllImportSearchPaths(DllImportSearchPath.System32)]
    internal static extern int NtQuerySystemInformation(SYSTEM_INFORMATION_CLASS SystemInformationClass, [Out] SYSTEM_PROCESSOR_IDLE_INFORMATION[] SystemInformation, int SystemInformationLength, out int ReturnLength);
}