Machine.java

package swen90006.machine;

import java.util.Arrays;
import java.util.List;

public class Machine 
{
  /** arithmetic instructions each take three registers as arguments with the
   *  destination register appearing first
   */

  /** add rd rs1 rs2   =~   rd = rs1 + rs2 */
  public static final String INSTRUCTION_ADD = "add";

  /** sub rd rs1 rs2   =~   rd = rs1 - rs2 */    
  public static final String INSTRUCTION_SUBTRACT = "sub";

  /** mul rd rs1 rs2   =~   rd = rs1 * rs2 */        
  public static final String INSTRUCTION_MULT = "mul";

  /** div rd rs1 rs2   =~   rd = rs1 / rs2 */            
  public static final String INSTRUCTION_DIVIDE = "div";

  /** ret rs           =~   return rs */
  public static final String INSTRUCTION_RETURN = "ret";

  /** ldr rd rs offs  =~    rd = rs[offs] */
  public static final String INSTRUCTION_LOAD = "ldr";

  /** str ra offs rb   =~    ra[offs] = rb */
  public static final String INSTRUCTION_STORE = "str";

  /** mov rd val       =~    rd = val */
  public static final String INSTRUCTION_MOVE = "mov";

  /** jmp offs         =~    pc = pc + offs */
  public static final String INSTRUCTION_JUMP = "jmp";

  /** jz ra offs       =~   if (ra == 0) pc = pc + offs else pc = pc + 1 */
  public static final String INSTRUCTION_JZ = "jz";
    
  public static final int NUM_REGS = 32;
  public static final int MAX_REG = (NUM_REGS - 1);
  public static final int MEMORY_SIZE = 65536; /* 4 x as much memory as a 64 */
  public static final int MAX_ADDR = MEMORY_SIZE-1;
    
  private int[] memory;
  private int[] regs;

  private int count = 0; /* counts number of instructions executed so far */
    
  public Machine()
  {
    memory = new int[MEMORY_SIZE];
    regs = new int[NUM_REGS];
    count = 0;
  }

  private void do_add(int dest, int src1, int src2)
  {
    regs[dest] = regs[src1] + regs[src2];
  }
    
  private void do_sub(int dest, int src1, int src2)
  {
    regs[dest] = regs[src1] - regs[src2];
  }
    
  private void do_mult(int dest, int src1, int src2)
  {