--- a/runtime/plc_common_main.c	Fri Jun 27 09:38:16 2008 +0200
+++ b/runtime/plc_common_main.c	Fri Jun 27 16:21:22 2008 +0200
@@ -1,3 +1,9 @@
+/*
+ * Prototypes for function provided by arch-specific code (main)
+ * concatained after this template
+ ** /
+
+
 /*
  * Functions and variables provied by generated C softPLC
  **/ 
@@ -39,6 +45,9 @@
 {
     %(retrieve_calls)s
     
+	/*
+	printf("run tick = %%d\n", tick + 1);
+	*/
     config_run__(tick++);
     
     %(publish_calls)s
@@ -63,3 +72,88 @@
     %(cleanup_calls)s
 }
 
+
+void PLC_GetTime(IEC_TIME *CURRENT_TIME);
+void PLC_SetTimer(long long next, long long period);
+
+#define CALIBRATED -2
+#define NOT_CALIBRATED -1
+static int calibration_count = NOT_CALIBRATED;
+static IEC_TIME cal_begin;
+static long long Tsync = 0;
+static long long FreqCorr = 0;
+static int Nticks = 0;
+static int  last_tick = 0;
+static long long Ttick = 0;
+#define mod %%
+/*
+ * Call this on each external sync, 
+ **/
+void align_tick(int calibrate)
+{
+	/*
+	printf("align_tick(%%d)\n", calibrate);
+	*/
+	if(calibrate){
+		if(calibration_count == CALIBRATED)
+			/* Re-calibration*/
+			calibration_count = NOT_CALIBRATED;
+		if(calibration_count == NOT_CALIBRATED)
+			/* Calibration start, get time*/
+			PLC_GetTime(&cal_begin);
+		calibration_count++;
+	}else{
+		if(calibration_count >= 0){
+			/* End of calibration */
+			/* Get final time */
+			IEC_TIME cal_end;
+			PLC_GetTime(&cal_end);
+			/*adjust calibration_count*/
+			calibration_count++;
+			/* compute mean of Tsync, over calibration period */	
+			Tsync = ((long long)(cal_end.tv_sec - cal_begin.tv_sec) * (long long)1000000000 +
+					(cal_end.tv_nsec - cal_begin.tv_nsec)) / calibration_count;
+			if( (Nticks = (Tsync / Ttick)) > 0){
+				FreqCorr = (Tsync mod Ttick); /* to be divided by Nticks */
+			}else{
+				FreqCorr = Tsync - (Ttick mod Tsync);
+			}
+			/*
+			printf("Tsync = %%ld\n", Tsync);
+			printf("calibration_count = %%d\n", calibration_count);
+			printf("Nticks = %%d\n", Nticks);
+			*/
+			calibration_count = CALIBRATED;
+		}
+		if(calibration_count == CALIBRATED){
+			/* Get Elapsed time since last PLC tick (__CURRENT_TIME) */
+			IEC_TIME now;
+			long long elapsed;
+			long long Tcorr;
+			long long PhaseCorr;
+			long long PeriodicTcorr;
+			PLC_GetTime(&now);
+			elapsed = (now.tv_sec - __CURRENT_TIME.tv_sec) * 1000000000 + now.tv_nsec - __CURRENT_TIME.tv_nsec;
+			if(Nticks > 0){
+				PhaseCorr = elapsed - (Ttick + FreqCorr/Nticks)*%(sync_align_ratio)d/100; /* to be divided by Nticks */
+				Tcorr = Ttick + (PhaseCorr + FreqCorr) / Nticks;
+				if(Nticks < 2){
+					/* When Sync source period is near Tick time */
+					/* PhaseCorr may not be applied to Periodic time given to timer */
+					PeriodicTcorr = Ttick + FreqCorr / Nticks;
+				}else{
+					PeriodicTcorr = Tcorr; 
+				}
+			}else if(tick > last_tick){
+				last_tick = tick;
+				PhaseCorr = elapsed - (Tsync*%(sync_align_ratio)d/100);
+				PeriodicTcorr = Tcorr = Ttick + PhaseCorr + FreqCorr;
+			}else{
+				/*PLC did not run meanwhile. Nothing to do*/
+				return;
+			}
+			/* DO ALIGNEMENT */
+			PLC_SetTimer(Tcorr - elapsed, PeriodicTcorr);
+		}
+	}
+}