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Respect different behaviour of RS and SR flip flops

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No more invalid states here.
According to IEC 61131, RS flip flop have dominant reset and SR have
dominant set. This is now implemented.
This commit is contained in:
Torsten Dreyer 2010-05-27 22:22:01 +02:00
parent 321bbeb2e8
commit 54c964aed5
1 changed files with 15 additions and 5 deletions
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20
src/Autopilot/xmlauto.cxx
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@ -918,9 +918,15 @@ void FGXMLAutoLogic::update(double dt)
} }
class FGXMLAutoRSFlipFlop : public FGXMLAutoFlipFlop { class FGXMLAutoRSFlipFlop : public FGXMLAutoFlipFlop {
private:
bool _rs;
public: public:
FGXMLAutoRSFlipFlop( SGPropertyNode * node ) : FGXMLAutoRSFlipFlop( SGPropertyNode * node ) :
FGXMLAutoFlipFlop( node ) {} FGXMLAutoFlipFlop( node ) {
// type exists here, otherwise we were not constructed
string val = node->getNode( "type" )->getStringValue();
_rs = (val == "RS");
}
void updateState( double dt ) { void updateState( double dt ) {
@ -940,9 +946,13 @@ public:
// s == false && q == false: no change, keep state // s == false && q == false: no change, keep state
if( s || r ) { if( s || r ) {
bool q = false; bool q = false;
if( s ) q = true; // set if( _rs ) { // RS: reset is dominant
if( r ) q = false; // reset if( s ) q = true; // set
// s && q: race condition. we let r win if( r ) q = false; // reset
} else { // SR: set is dominant
if( r ) q = false; // reset
if( s ) q = true; // set
}
if( inverted ) q = !q; if( inverted ) q = !q;
if ( debug ) cout << "Updating " << get_name() << ":" if ( debug ) cout << "Updating " << get_name() << ":"
@ -1374,7 +1384,7 @@ bool FGXMLAutopilot::build( SGPropertyNode_ptr config_props ) {
string val; string val;
if( typeNode != NULL ) val = typeNode->getStringValue(); if( typeNode != NULL ) val = typeNode->getStringValue();
val = simgear::strutils::strip(val); val = simgear::strutils::strip(val);
if( val == "RS" || val =="SR" ) flipFlop = new FGXMLAutoRSFlipFlop( node ); if( val == "RS" || val =="SR" ) flipFlop = new FGXMLAutoRSFlipFlop( node );
else if( val == "JK" ) flipFlop = new FGXMLAutoJKFlipFlop( node ); else if( val == "JK" ) flipFlop = new FGXMLAutoJKFlipFlop( node );
else if( val == "T" ) flipFlop = new FGXMLAutoTFlipFlop( node ); else if( val == "T" ) flipFlop = new FGXMLAutoTFlipFlop( node );
else if( val == "D" ) flipFlop = new FGXMLAutoDFlipFlop( node ); else if( val == "D" ) flipFlop = new FGXMLAutoDFlipFlop( node );