public static IGate ExtractCommonFactors(IGate gate)
{
var original = gate;
if (gate.Type == GateType.OR)
{
// TraceOptimize("extract common factors from {0} ...", gate);
var sop = gate.GetSOP();
// count how many times each factor appears
var inmap = new Dictionary <int, IInput>();
var dict = new SortedList <int, int>();
foreach (var p in sop.GetPrimitiveFactors())
{
// a gate representing the factors (may be multiple per state variable)
var pg = p.ToGate();
foreach (var i in pg.GetInputs().OfType <IInput>())
{
var address = i.Address;
// TraceOptimize("check factor {0} @ {1:X6}", i, address);
if (!inmap.ContainsKey(i.Address))
{
inmap.Add(i.Address, i);
}
if (!dict.ContainsKey(address))
{
dict[address] = 1;
}
else
{
dict[address]++;
}
}
}
var m = dict.Values.Max();
// TraceOptimize("maximum factor count {0}", m);
if (m > 1)
{
// go for it, take the first input with maximum multiplicity, inputs are ordered.
var pivotindex = dict.Where(e => e.Value == m).Select(e => e.Key).First();
var pivot = inmap[pivotindex];
var pivotlist = new List <Product>();
var otherlist = new List <Product>();
TraceOptimize("use pivot {0:X6} ...", pivot);
// split sop into two groups: factor or not
foreach (var p in sop)
{
if (p.ContainsFactor(pivot))
{
p.RemoveInput(pivot);
pivotlist.Add(p);
}
else
{
otherlist.Add(p);
}
}
IGate and = new ANDGate();
and.AddInput(pivot);
IGate inneror = new ORGate();
foreach (var p in pivotlist)
{
var z = p.ToGate().Simplify();
// Debug.Assert(z.GetInputs().Count() > 1);
Trace("adding pivot {0} [{1}]", z, z.GetType().Name);
inneror.AddInput(z);
}
inneror = ExtractCommonFactors(inneror);
and.AddInput(inneror);
if (otherlist.Any())
{
//var rh = ExtractCommonFactors(otherlist);
var or = new ORGate();
or.AddInput(and);
foreach (var p in otherlist)
{
var z = p.ToGate();
or.AddInput(z.Simplify());
}
gate = or;
}
else
{
gate = and;
}
}
}
if (gate != original && TraceFlags.ShowOptimize)
{
Log.TraceGateOp2(original, gate, "optimize AND");
}
return(gate);
}
/// <summary>
/// Composes two gates with the logical AND operator.
/// </summary>
/// <param name="a"></param>
/// <param name="b"></param>
/// <returns>The resulting gate.</returns>
public static IGate ComposeAND(IGate a, IGate b)
{
IGate result;
DecomposeExchange(ref a, ref b);
if (a.Type == GateType.Fixed && b.Type == GateType.Fixed)
{
if (a is TrueGate && b is TrueGate)
{
result = new TrueGate();
}
else
{
result = new FalseGate();
}
}
else if (b.Type == GateType.Fixed)
{
if (b is TrueGate)
{
result = a;
}
else
{
result = new FalseGate();
}
}
else if (a.Type == GateType.OR && b.Type == GateType.OR)
{
result = Multiply(a.GetInputs(), b.GetInputs());
}
else if (a.Type == GateType.OR)
{
result = Multiply(a.GetInputs(), b);
}
else if (a.Type == GateType.AND && b.Type == GateType.AND)
{
// compose
var r = new ANDGate();
r.AddInputRange(a.GetInputs());
r.AddInputRange(b.GetInputs());
result = r;
}
else if (a.Type == GateType.AND)
{
// compose
var r = new ANDGate();
r.AddInputRange(a.GetInputs());
r.AddInput(b);
result = r;
}
else
{
var r = new ANDGate();
r.AddInput(a);
r.AddInput(b);
result = r;
}
// simplify and cache
result = Simplify(result);
TraceCompose(a, b, result, "AND");
return(result);
}