import ch.psi.pshell.device.PositionerConfig as PositionerConfig
import ch.psi.pshell.device.Speedable as Speedable


class PseudoMotor(PositionerBase, Speedable):    
    def __init__(self, name):
        PositionerBase.__init__(self, name, PositionerConfig())
        self.rbck  = 0.0
        self.setp  = 0.0
        self.settime = time.time()
        
    def doRead(self):     
        return self.setp
        
    def doWrite(self, val):
        self.setp = val
        self.settime = time.time()

    def doReadReadback(self):
         offset = self.setp - self.rbck
         d = (self.speed * (time.time() - self.settime))
         d = min(d, abs(offset))         
         self.rbck = self.rbck + d if offset>0 else self.rbck -d
         self.settime = time.time()
         return self.rbck

    def getSpeed(self):
        return 3.0
        
positioner =  PseudoMotor("PseudoMotor")       
add_device(positioner, True);

show_panel(PseudoMotor)
cscan(positioner, MachineCurrent, 0, 10, 1.0)