using System;
namespace hwo.bitworks
{
	public class ShiftArithmeticRight : MultipleBitsSource
	{
		int n;

		public ShiftArithmeticRight(LogicBase[] sources,int n)
			:base(sources)
		{
			this.n = n;
		}

		public override bool bitValue(int bit)
		{
			if (bit < (getBits()-this.n)){
				return sources[bit + this.n].value();
			} else if (bit < getBits()){
				return sources[getBits()-1].value();
			};

			throw new IndexOutOfRangeException(String.Format("ShiftRight supplies {0} bits, but bit #{1} requested",getBits(),bit));
		}

		public override identity.BitIdentity getBitIdentity(int bit)
		{
			if (bit < (getBits()-this.n)){
				return sources[bit + this.n].identity();
			} else if (bit < getBits()){
				return sources[getBits()-1].identity();
			};

			throw new IndexOutOfRangeException(String.Format("ShiftRight supplies {0} bits, but bit #{1} requested",getBits(),bit));
		}
	}
}