/// <summary>
/// Find the best Bitfield and the best BitfieldSet, and choose whichever has the highest quality.
/// </summary>
/// <param name="maxBits">Maximum number of bits to select.</param>
/// <returns></returns>
private SwitchableNode?FindBestSwitchable(int maxBits)
{
Debug.Assert(maxBits >= 0 && maxBits < spec.NumBits);
// find a single bitfield on which we can switch
Bitfield?bitfield = analyser.FindBestBitfield(spec.Config.MinSwitchBits, maxBits);
if (bitfield == null)
{
// if we can't find even a low-quality single bitfield,
// we won't find a split one, so just fail
return(null);
}
if (spec.Config.Verbose)
{
Console.WriteLine("Best single bitfield has quality {0}", bitfield.Quality);
}
SwitchableNode node = bitfield;
// find a split bitfield
BitfieldSet?bitfieldSet = analyser.FindBestBitfieldSet(spec.Config.MinSwitchBits, maxBits);
if (bitfieldSet != null)
{
if (spec.Config.Verbose)
{
Console.WriteLine("Best bitfield set has quality {0}", bitfieldSet.Quality);
}
// select either the single or the split bitfield, depending on
// which has the highest quality
if (bitfieldSet.Quality > bitfield.Quality)
{
node = bitfieldSet;
}
}
return(node);
}
/// <summary>
/// Actually build the switch node, given the supplied expression.
/// </summary>
/// <param name="expression">Either a bitfield or a bitfield set.</param>
/// <returns>Bitfield node object.</returns>
private SwitchNode BuildSwitch(SwitchableNode expression)
{
if (spec.Config.Verbose)
{
Console.WriteLine("Building switch node for {0}.", expression.ToString());
}
var node = new SwitchNode(spec, expression);
// iterate through every possible value of 'expression'
for (int value = 0; value < expression.NumValues; value++)
{
// store child in switch node's table
node[value] = BuildSwitchCase(node, value);
}
if (spec.Config.Verbose)
{
Console.WriteLine("Switch completed.");
}
return(node);
}
/// <summary>
/// Initializes a new instance of the <see cref="SwitchNode"/> class.
/// </summary>
public SwitchNode(Specification spec, SwitchableNode expression)
: base(spec)
{
this.expression = expression;
children = new Node[expression.NumValues];
}
