J.java

/*
 * J.java
 *
 *  8th may 2006
 * Instruction J of the MIPS64 Instruction Set
 * (c) 2006 EduMips64 project - Trubia Massimo, Russo Daniele
 *
 * This file is part of the EduMIPS64 project, and is released under the GNU
 * General Public License.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
package org.edumips64.core.is;
import org.edumips64.core.*;
import org.edumips64.utils.*;
/**
 * <pre>
 *      Syntax: J targetJ
 * Description: To branch within the current 256 MB-aligned region
 *               This is a PC-region branch (not PC-relative); the effective
 *              target address is in the “current” 256 MB-aligned region.
 *</pre>
 * @author Trubia Massimo, Russo Daniele
 *
 */

public class J extends FlowControl_JType {
  final String OPCODE_VALUE = "000010";

  /** Creates a new instance of J */
  J() {
    super.OPCODE_VALUE = OPCODE_VALUE;
    this.name = "J";
  }

  public void ID() throws RAWException, IrregularWriteOperationException, IrregularStringOfBitsException, JumpException {
    //converting INSTR_INDEX into a bynary value of 26 bits in length
    String instr_index = Converter.positiveIntToBin(28, params.get(INSTR_INDEX));
    //appending the 35 most significant bits of the program counter on the left of "instr_index"
    Register pc = cpu.getPC();
    String pc_all = pc.getBinString();
    String pc_significant = pc_all.substring(0, 36);
    String pc_new = pc_significant + instr_index;
    pc.setBits(pc_new, 0);
    throw new JumpException();
  }

  public void EX() throws IrregularStringOfBitsException, IntegerOverflowException {
  }

  public void MEM() throws IrregularStringOfBitsException, MemoryElementNotFoundException {
  }

  public void WB() throws IrregularStringOfBitsException {
  }

}