/// <summary>
/// Visits a parentheses expression.
/// </summary>
/// <param name="expression">the parentheses expression</param>
protected internal virtual void visitParentheses(Parentheses expression)
{
visit(expression.Expression);
}
/// <summary>
/// Returns the clock signal in an edge condition.
/// If the expression is no edge condition <code>null</code> is returned.
/// <p>Recognized expressions:
/// <code><ul>
/// <li>clock'event and clock = '0'
/// <li>clock'event and clock = '1'
/// <li>clock = '0' and clock'event
/// <li>clock = '1' and clock'event
/// <li>not clock'stable and clock = '0'
/// <li>not clock'stable and clock = '1'
/// <li>clock = '0' and not clock'stable
/// <li>clock = '1' and not clock'stable
/// <li>falling_edge(clock)
/// <li>rising_edge(clock)
/// </ul></code>
/// </summary>
/// <param name="expression">the expression</param>
/// <returns>the clock signal or <code>null</code></returns>
public static Signal getEdgeConditionClock(Expression expression)
{
if (expression is BinaryExpression)
{
BinaryExpression binExpr = toBinaryExpression(expression, ExpressionKind.AND);
if (binExpr == null)
{
return(null);
}
Signal clock = clockLevelToSignal(binExpr.Left);
if (clock != null)
{
return(isEventExpression(binExpr.Right, clock) ? clock : null);
}
clock = clockLevelToSignal(binExpr.Right);
if (clock != null)
{
return(isEventExpression(binExpr.Left, clock) ? clock : null);
}
}
else if (expression is FunctionCall)
{
FunctionCall call = (FunctionCall)expression;
if (call.Function.Equals(StdLogic1164.FALLING_EDGE) || call.Function.Equals(StdLogic1164.RISING_EDGE))
{
if (call.Parameters.Count == 1)
{
AssociationElement ae = call.Parameters[0];
if (ae.Actual is Name)
{
var obj = (ae.Actual as Name).Referenced;
if (obj is Signal)
{
return(obj as Signal);
}
}
}
}
}
else if (expression is Parentheses)
{
Parentheses p = (Parentheses)expression;
return(getEdgeConditionClock(p.Expression));
}
else if (expression is Aggregate)
{
Aggregate a = (Aggregate)expression;
if (a.Associations.Count != 1)
{
return(null);
}
ElementAssociation association = a.Associations[0];
if (association.Choices.Count == 0)
{
return(getEdgeConditionClock(association.Expression));
}
}
return(null);
}