delphi linux11 QueryPerformanceCounter替代

在 Linux 中，可以使用 clock_gettime 函数来获取高精度的时间戳，并计算出时间间隔。具体来说，您可以使用 CLOCK_MONOTONIC 时钟来获取单调递增的时间戳。然后您可以使用 TStopwatch 类型来模拟 QueryPerformanceCounter 函数。以下是一个示例代码片段，展示如何在 Delphi 中计算时间间隔：

{$IFDEF LINUX}
  {$DEFINE _POSIX_C_SOURCE := 199309L} // 定义 _POSIX_C_SOURCE 宏
  {$LINKLIB c} // 链接 C 库
  {$LINKLIB rt} // 链接实时库
{$ENDIF}

uses
  Posix.Time;

type
  TStopwatch = record
  private
    FStartTicks: Int64;
    FStopTicks: Int64;
    FElapsed: Int64;
    FRunning: Boolean;
    FResolution: Int64;
    class function GetTicks: Int64; static; inline;
  public
    procedure Start;
    procedure Stop;
    procedure Reset;
    function ElapsedMilliseconds: Int64;
    function ElapsedTicks: Int64;
    function IsRunning: Boolean;
    class function GetTimeStamp: Int64; static; inline;
    class function Frequency: Int64; static; inline;
  end;

class function TStopwatch.GetTicks: Int64;
var
  ts: TTimeSpec;
begin
  clock_gettime(CLOCK_MONOTONIC, @ts);
  Result := Int64(ts.tv_sec) * 1000000000 + ts.tv_nsec;
end;

procedure TStopwatch.Start;
begin
  if not FRunning then
  begin
    FStartTicks := GetTicks;
    FRunning := True;
  end;
end;

procedure TStopwatch.Stop;
begin
  if FRunning then
  begin
    FStopTicks := GetTicks;
    FElapsed := FElapsed + FStopTicks - FStartTicks;
    FRunning := False;
  end;
end;

procedure TStopwatch.Reset;
begin
  FElapsed := 0;
  FStartTicks := 0;
  FStopTicks := 0;
  FRunning := False;
end;

function TStopwatch.ElapsedMilliseconds: Int64;
begin
  Result := ElapsedTicks * 1000 div Frequency;
end;

function TStopwatch.ElapsedTicks: Int64;
begin
  Result := FElapsed;
  if FRunning then
    Result := Result + GetTicks - FStartTicks;
end;

function TStopwatch.IsRunning: Boolean;
begin
  Result := FRunning;
end;

class function TStopwatch.GetTimeStamp: Int64;
begin
  Result := GetTicks;
end;

class function TStopwatch.Frequency: Int64;
begin
  Result := 1000000000;
end;

在上述代码中，我们定义了一个 TStopwatch 类型来模拟 QueryPerformanceCounter 函数，使用 clock_gettime 函数获取时间戳，并计算出时间间隔。需要注意的是，clock_gettime 函数返回的时间戳是以秒为单位的，因此需要将其转换为纳秒。