Sar.java

package builtin.operator;

import builtin.BuiltinSub;
import java.math.BigInteger;
import gui.Constants;
import gui.Heap;
import gui.MintException;
import gui.Pointer;
import gui.PointerTools;
import gui.SmartList;

/**
 *
 * @author Oliver Chu
 */
public class Sar extends BuiltinSub {

    @Override
    public Pointer apply(SmartList<Pointer> args) throws MintException {
        Pointer arg0 = args.get(0);
        Pointer arg1 = args.get(1);
        if (arg0.type == Constants.BIG_INT_TYPE &&
            arg1.type == Constants.BIG_INT_TYPE) {
            BigInteger bi0 = PointerTools.dereferenceBigInt(arg0);
            BigInteger bi1 = PointerTools.dereferenceBigInt(arg1);
            return Heap.allocateBigInt(bi0.shiftRight(bi1.intValue()));
        }
        if (arg0.type == Constants.INT_TYPE && arg1.type == Constants.INT_TYPE)
        {
            int operand0 = PointerTools.dereferenceInt(arg0);
            int operand1 = PointerTools.dereferenceInt(arg1);
            return Heap.allocateInt(operand0 >> operand1);
        } else {
            throw new MintException("Sign-propagating shift right can only " + 
                                    "be applied to integers.");
        }
    }
    
}