private static IGate ConsolidateList(List<IGate> list)
{
IGate gate;
if (!list.Any())
{
// empty sum => FALSE
gate = new FalseGate();
}
else if (list.Count == 1)
{
gate = list.First();
}
else
{
var or = new ORGate();
or.AddInputRange(list);
gate = or;
}
return gate;
}
private static IGate ConsolidateList(List <IGate> list)
{
IGate gate;
if (!list.Any())
{
// empty sum => FALSE
gate = new FalseGate();
}
else if (list.Count == 1)
{
gate = list.First();
}
else
{
var or = new ORGate();
or.AddInputRange(list);
gate = or;
}
return(gate);
}
/// <summary>
/// Returns a gate that represents the inverted output of another gate.
/// </summary>
/// <param name="a">The gate to be inverted.</param>
/// <returns>The inverted gate.</returns>
public static IGate Invert(IGate g)
{
IGate result;
IGate a = Decompose(g);
if (a.Type == GateType.OR)
{
var it = a.GetInputs().GetEnumerator();
it.MoveNext();
var r = Invert(it.Current);
while (it.MoveNext())
{
r = ComposeAND(r, Invert(it.Current));
}
result = r;
}
else if (a.Type == GateType.AND)
{
var it = a.GetInputs().GetEnumerator();
it.MoveNext();
var r = Invert(it.Current);
while (it.MoveNext())
{
r = ComposeOR(r, Invert(it.Current));
}
result = r;
}
else if (a.Type == GateType.Input)
{
result = ((IInput)a).Invert();
}
else if(a.Type == GateType.Fixed)
{
if(a is TrueGate)
{
result = new FalseGate();
}
else
{
result = new TrueGate();
}
}
else
{
throw new ArgumentException();
}
result = Simplify(result);
TraceCompose(g, result, "invert");
return result;
}
public static IGate ComposeOR(IEnumerable<IGate> gates)
{
IGate r = new FalseGate();
var it = gates.GetEnumerator();
while (it.MoveNext())
{
r = ComposeOR(r, it.Current);
}
return r;
}
/// <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;
}
private bool SimplifyRule1(ref IGate gate)
{
var original = gate;
var garg = gate as ORGate;
if(null == garg) return false;
// handle the rules:
// A + !A B = A + B
// A + A B = A
var gset = garg.GetSOP();
int changes = 0;
var gplan = gset.OrderBy(e => e.Inputs.Count()).ToList();
for (int j = 0; j < gplan.Count; ++j)
{
var glist = gplan[j];
if (glist.IsEmpty) continue;
TraceSimplify(" product [{0}] : {1}", glist.Signature, glist.ToGate());
for (int k = j + 1; k < gplan.Count; ++k)
{
var olist = gplan[k];
switch (olist.ContainsFactor(glist))
{
case 1:
// contains the sequence => eliminate entry?
TraceSimplify(" is contained in {0} ...", olist.ToGate());
olist.Clear();
changes++;
break;
case 2:
// contains negation => remove negations
TraceSimplify(" negation is contained in {0} ...", olist.ToGate());
olist.Remove(glist);
if(olist.IsEmpty)
{
// full negation ==> ALL
glist.Clear();
gset.Fixed = new TrueGate();
}
changes++;
break;
}
}
}
gset.Purge();
if (gset.Fixed != null)
{
gate = gset.Fixed;
}
else
{
// construct an OR expression containing the ordered factors
var or = new ORGate();
foreach (var glist in gset.OrderBy(e => e.Signature, StringComparer.Ordinal))
{
or.AddInput(glist.ToGate().Simplify());
}
if (or.Inputs.Count() == 0)
{
gate = new FalseGate();
}
else if (or.Inputs.Count() == 1)
{
gate = or.Inputs.First();
}
else
{
gate = or;
}
}
if (changes > 0)
{
TraceSimplify(original, gate, "simplify OR (1)");
}
return changes > 0;
}
private bool SimplifyRule1(ref IGate gate)
{
var original = gate;
var garg = gate as ORGate;
if (null == garg)
{
return(false);
}
// handle the rules:
// A + !A B = A + B
// A + A B = A
var gset = garg.GetSOP();
int changes = 0;
var gplan = gset.OrderBy(e => e.Inputs.Count()).ToList();
for (int j = 0; j < gplan.Count; ++j)
{
var glist = gplan[j];
if (glist.IsEmpty)
{
continue;
}
TraceSimplify(" product [{0}] : {1}", glist.Signature, glist.ToGate());
for (int k = j + 1; k < gplan.Count; ++k)
{
var olist = gplan[k];
switch (olist.ContainsFactor(glist))
{
case 1:
// contains the sequence => eliminate entry?
TraceSimplify(" is contained in {0} ...", olist.ToGate());
olist.Clear();
changes++;
break;
case 2:
// contains negation => remove negations
TraceSimplify(" negation is contained in {0} ...", olist.ToGate());
olist.Remove(glist);
if (olist.IsEmpty)
{
// full negation ==> ALL
glist.Clear();
gset.Fixed = new TrueGate();
}
changes++;
break;
}
}
}
gset.Purge();
if (gset.Fixed != null)
{
gate = gset.Fixed;
}
else
{
// construct an OR expression containing the ordered factors
var or = new ORGate();
foreach (var glist in gset.OrderBy(e => e.Signature, StringComparer.Ordinal))
{
or.AddInput(glist.ToGate().Simplify());
}
if (or.Inputs.Count() == 0)
{
gate = new FalseGate();
}
else if (or.Inputs.Count() == 1)
{
gate = or.Inputs.First();
}
else
{
gate = or;
}
}
if (changes > 0)
{
TraceSimplify(original, gate, "simplify OR (1)");
}
return(changes > 0);
}
