avoid multiple running drive tasks for the same object

devexec.c

@@ -279,6 +279,8 @@ int StartDevice(pExeList self, char *name, pObjectDescriptor pDes,
     return 0;
   }
 
+  EndDriveTask(pData); /* BEGIN experimental: stop pending drive task for this objects immediately */
+
   SetDevexecStatus(self,DEVDONE);
   if(self->waitID < 0 && level == RUNDRIVE){
     self->waitID = GetTaskGroupID(pServ->pTasker);

event.h

@@ -70,6 +70,7 @@ typedef struct {
 #define TOKENRELEASE  303
 #define COMLOG        304
 #define CRONFUNC      305
+#define ENDDRIVETASK  306
 
 #line 131 "event.w"
  

interface.c

@@ -224,9 +224,23 @@ static void DriveTaskSignal(void *data, int iSignal, void *pSigData)
       taskData->pDriv->Halt(taskData->obj);
       SCSetInterrupt(taskData->pCon,*interrupt);
     }
+  } else if (iSignal == ENDDRIVETASK) {
+    if (taskData->obj == pSigData) {
+      taskData->pDriv = NULL;  /* tell DriveTaskFunc to quit */
+    }
   }
 }
 /*--------------------------------------------------------------------------*/
+void EndDriveTask(void *obj) {
+  /* End a drive task for obj.
+     Originally in SICS, it was not possible to run an object already running
+     this was relaxed in SEA, but with the downside, that several drive tasks
+     for the same object may be running, removed only when the run succeds.
+     This is called in StartDevice, before creating a new drive task.
+  */
+  TaskSignal(pServ->pTasker, ENDDRIVETASK, obj);
+}
+/*--------------------------------------------------------------------------*/
 static int DriveTaskFunc(void *data)
 {
   DriveTaskData *taskData = (DriveTaskData *)data;
@@ -234,6 +248,7 @@ static int DriveTaskFunc(void *data)
 
   assert(taskData != NULL);
 
+  if (!taskData->pDriv) return 0;
 
   status = taskData->pDriv->CheckStatus(taskData->obj,taskData->pCon);
   if(status == HWBusy){

interface.h

@@ -48,6 +48,8 @@
                                  float *fPos);
 
         long StartDriveTask(void *self, SConnection *pCon, char *name,  float fTarget);
+        void EndDriveTask(void *data);
+        /* end a drive task replaced by a new one with the same object*/
 
 
 #line 438 "interface.w"