+FGPeriodicalValue::FGPeriodicalValue( SGPropertyNode_ptr root )
+{
+ SGPropertyNode_ptr minNode = root->getChild( "min" );
+ SGPropertyNode_ptr maxNode = root->getChild( "max" );
+ if( minNode == NULL || maxNode == NULL ) {
+ SG_LOG(SG_AUTOPILOT, SG_ALERT, "periodical defined, but no <min> and/or <max> tag. Period ignored." );
+ } else {
+ minPeriod = new FGXMLAutoInput( minNode );
+ maxPeriod = new FGXMLAutoInput( maxNode );
+ }
+}
+
+double FGPeriodicalValue::normalize( double value )
+{
+ if( !(minPeriod && maxPeriod )) return value;
+
+ double p1 = minPeriod->get_value();
+ double p2 = maxPeriod->get_value();
+
+ double min = std::min<double>(p1,p2);
+ double max = std::max<double>(p1,p2);
+ double phase = fabs(max - min);
+
+ if( phase > SGLimitsd::min() ) {
+ while( value < min ) value += phase;
+ while( value > max ) value -= phase;
+ } else {
+ value = min; // phase is zero
+ }
+
+ return value;
+}
+