using System.Runtime.InteropServices;
namespace Vanara.PInvoke
{
public static partial class Kernel32
{
///
/// Retrieves the current value of the performance counter, which is a high resolution (<1us) time stamp that can be used for
/// time-interval measurements.
///
/// A pointer to a variable that receives the current performance-counter value, in counts.
///
/// If the function succeeds, the return value is nonzero.
///
/// If the function fails, the return value is zero. To get extended error information, call GetLastError. On systems that run
/// Windows XP or later, the function will always succeed and will thus never return zero.
///
///
/// For more info about this function and its usage, see Acquiring high-resolution time stamps.
// https://docs.microsoft.com/en-us/windows/win32/api/profileapi/nf-profileapi-queryperformancecounter BOOL QueryPerformanceCounter(
// LARGE_INTEGER *lpPerformanceCount );
[DllImport(Lib.Kernel32, SetLastError = true, ExactSpelling = true)]
[PInvokeData("profileapi.h")]
[return: MarshalAs(UnmanagedType.Bool)]
public static extern bool QueryPerformanceCounter(out long lpPerformanceCount);
///
/// Retrieves the frequency of the performance counter. The frequency of the performance counter is fixed at system boot and is
/// consistent across all processors. Therefore, the frequency need only be queried upon application initialization, and the result
/// can be cached.
///
///
/// A pointer to a variable that receives the current performance-counter frequency, in counts per second. If the installed hardware
/// doesn't support a high-resolution performance counter, this parameter can be zero (this will not occur on systems that run
/// Windows XP or later).
///
///
/// If the installed hardware supports a high-resolution performance counter, the return value is nonzero.
///
/// If the function fails, the return value is zero. To get extended error information, call GetLastError. On systems that run
/// Windows XP or later, the function will always succeed and will thus never return zero.
///
///
/// For more info about this function and its usage, see Acquiring high-resolution time stamps.
// https://docs.microsoft.com/en-us/windows/win32/api/profileapi/nf-profileapi-queryperformancefrequency BOOL
// QueryPerformanceFrequency( LARGE_INTEGER *lpFrequency );
[DllImport(Lib.Kernel32, SetLastError = true, ExactSpelling = true)]
[PInvokeData("profileapi.h")]
[return: MarshalAs(UnmanagedType.Bool)]
public static extern bool QueryPerformanceFrequency(out long lpFrequency);
}
}