/// <summary>
/// try to insert registers in cyclic paths starting at (1) feedbackInputNode's input terminals and (2) RightShiftRegister's output terminal
/// </summary>
private void FixSolutionForComboCycles()
{
foreach (var v in Graph.Vertices.Where(v => v.IsTerminal() &&
!Registered(v) &&
(v.NodeType == DelayGraphNodeType.FeedbackInputNode ||
(v.NodeType == DelayGraphNodeType.RightShiftRegister &&
v.IsOutputTerminal))))
{
foreach (var e in Graph.GetFeedbackOutEdges(v))
{
var next = e.Target;
if (Registered(next))
{
continue;
}
var visited = new HashSet <DelayGraphVertex>();
if (FindForwardPath(next, v, visited))
{
// there is a combo path from v to itself via next - fix the cycle by registering next
if (v.DisallowRegister)
{
if (v.NodeType == DelayGraphNodeType.FeedbackInputNode)
{
// put registers on incoming forward edge's source, unless it is already registered or register is not allowed
foreach (var edge in Graph.GetForwardInEdges(v))
{
// register s iff ok to do so
var s = edge.Source;
if (!s.DisallowRegister && !Registered(s))
{
RegisteredTerminals.Add(s);
}
}
}
}
else
{
RegisteredTerminals.Add(v);
}
break;
}
}
}
}
private void RetimeRegister(DelayGraphVertex v)
{
if (v.IsInputTerminal)
{
// move v's register to incoming edges
foreach (var e in Graph.GetForwardInEdges(v))
{
RegisteredTerminals.Add(e.Source);
}
}
else
{
// move v's register to outgoing edges
foreach (var e in Graph.GetForwardOutEdges(v))
{
RegisteredTerminals.Add(e.Source);
}
}
RegisteredTerminals.Remove(v);
}
/// <summary>
/// fix sibling to be registered if any is registered
/// </summary>
/// <returns>a count of number of nodes that changed</returns>
private int FixSolutionForSiblingVertices()
{
int count = 0;
HashSet <DelayGraphVertex> grouped;
var listOfSiblings = DelayGraphAlgorithms.FindVertexGroups(Graph, out grouped);
foreach (var siblings in listOfSiblings)
{
if (siblings.Any(Registered) && siblings.Count() > 1)
{
// at least one in sibling is registered
var verticesWhichAreNotRegistered = siblings.Where(v => !Registered(v));
count += verticesWhichAreNotRegistered.Count();
foreach (var v in verticesWhichAreNotRegistered)
{
RegisteredTerminals.Add(v);
}
}
}
return(count);
}
private bool Registered(DelayGraphVertex v)
{
return(v.IsRegistered || RegisteredTerminals.Contains(v));
}
