1 files changed, 185 insertions, 0 deletions
diff --git a/src/Classes/UTime.pas b/src/Classes/UTime.pas
new file mode 100644
index 00000000..f8ae91c4
--- /dev/null
+++ b/src/Classes/UTime.pas
@@ -0,0 +1,185 @@
+unit UTime;
+
+interface
+
+{$IFDEF FPC}
+  {$MODE Delphi}
+{$ENDIF}
+
+{$I switches.inc}
+
+type
+  TTime = class
+    public
+      constructor Create;
+      function GetTime(): real;
+  end;
+
+  TRelativeTimer = class
+    private
+      AbsoluteTime: int64;      // system-clock reference time for calculation of CurrentTime
+      RelativeTimeOffset: real;
+      Paused: boolean;
+      TriggerMode: boolean;
+    public
+      constructor Create(TriggerMode: boolean = false);
+      procedure Pause();
+      procedure Resume();
+      function GetTime(): real;
+      function GetAndResetTime(): real;
+      procedure SetTime(Time: real; Trigger: boolean = true);
+      procedure Reset();
+  end;
+
+procedure CountSkipTimeSet;
+procedure CountSkipTime;
+procedure CountMidTime;
+
+var
+  USTime      : TTime;
+  VideoBGTimer: TRelativeTimer;
+
+  TimeNew     : int64;
+  TimeOld     : int64;
+  TimeSkip    : real;
+  TimeMid     : real;
+  TimeMidTemp : int64;
+
+implementation
+
+uses
+  sdl,
+  ucommon;
+  
+const
+  cSDLCorrectionRatio = 1000;
+
+(*
+BEST Option now ( after discussion with whiteshark ) seems to be to use SDL
+timer functions...
+
+SDL_delay
+SDL_GetTicks
+http://www.gamedev.net/community/forums/topic.asp?topic_id=466145&whichpage=1%EE%8D%B7
+*)
+
+
+procedure CountSkipTimeSet;
+begin
+  TimeNew     := SDL_GetTicks();
+end;
+
+procedure CountSkipTime;
+begin
+  TimeOld     := TimeNew;
+  TimeNew     := SDL_GetTicks();
+  TimeSkip    := (TimeNew-TimeOld) / cSDLCorrectionRatio;
+end;
+
+procedure CountMidTime;
+begin
+  TimeMidTemp := SDL_GetTicks();
+  TimeMid     := (TimeMidTemp - TimeNew) / cSDLCorrectionRatio;
+end;
+
+{**
+ * TTime
+ **}
+
+constructor TTime.Create;
+begin
+  inherited;
+  CountSkipTimeSet;
+end;
+
+function TTime.GetTime: real;
+begin
+  Result := SDL_GetTicks() / cSDLCorrectionRatio;
+end;
+
+{**
+ * TRelativeTimer
+ **}
+
+(*
+ * Creates a new timer.
+ * If TriggerMode is false (default), the timer
+ * will immediately begin with counting.
+ * If TriggerMode is true, it will wait until Get/SetTime() or Pause() is called
+ * for the first time.
+ *)
+constructor TRelativeTimer.Create(TriggerMode: boolean);
+begin
+  inherited Create();
+  Self.TriggerMode := TriggerMode;
+  Reset();
+  Paused := false;
+end;
+
+procedure TRelativeTimer.Pause();
+begin
+  RelativeTimeOffset := GetTime();
+  Paused := true;
+end;
+
+procedure TRelativeTimer.Resume();
+begin
+  AbsoluteTime := SDL_GetTicks();
+  Paused := false;
+end;
+
+(*
+ * Returns the counter of the timer.
+ * If in TriggerMode it will return 0 and start the counter on the first call.
+ *)
+function TRelativeTimer.GetTime: real;
+begin
+  // initialize absolute time on first call in triggered mode
+  if (TriggerMode and (AbsoluteTime = 0)) then
+  begin
+    AbsoluteTime := SDL_GetTicks();
+    Result := RelativeTimeOffset;
+    Exit;
+  end;
+
+  if Paused then
+    Result := RelativeTimeOffset
+  else
+    Result := RelativeTimeOffset + (SDL_GetTicks() - AbsoluteTime) / cSDLCorrectionRatio;
+end;
+
+(*
+ * Returns the counter of the timer and resets the counter to 0 afterwards.
+ * Note: In TriggerMode the counter will not be stopped as with Reset().
+ *)
+function TRelativeTimer.GetAndResetTime(): real;
+begin
+  Result := GetTime();
+  SetTime(0);
+end;
+
+(*
+ * Sets the timer to the given time. This will trigger in TriggerMode if
+ * Trigger is set to true. Otherwise the counter's state will not change.
+ *)
+procedure TRelativeTimer.SetTime(Time: real; Trigger: boolean);
+begin
+  RelativeTimeOffset := Time;
+  if ((not TriggerMode) or Trigger) then
+    AbsoluteTime := SDL_GetTicks();
+end;
+
+(*
+ * Resets the counter of the timer to 0.
+ * If in TriggerMode the timer will not start counting until it is triggered again.
+ *)
+procedure TRelativeTimer.Reset();
+begin
+  RelativeTimeOffset := 0;
+  if (TriggerMode) then
+    AbsoluteTime := 0
+  else
+    AbsoluteTime := SDL_GetTicks();
+end;
+
+end.