rpm.c

int delta;
float revs_last;
float RPM;

int scaleFactor;

while(true)
{
  delta = SensorValue[encoder];
  
  revs_last = (float)delta/scaleFactor;
  
  RPM = left_revs_last * 120;
  
  SensorValue[encoder] = 0;
  
  wait1Msec(500);
}