content: 
  package com.zylin.zpu.simulator;
  
  import com.zylin.zpu.simulator.exceptions.CPUException;
  
  public interface Host
  {
  	/** generic file io error */
  	public final static int  EIO =    5;
  	
      public final static int  SYS_read=    4;
      public final static int  SYS_write=   5;
  	public final static int  SYS_argv   = 13;
  	public final static int SYS_exit=1;
  	public final static int  SYS_open=    2;
  	public final static int  SYS_close=   3;
  	public final static int  SYS_lseek =  6;
  	public final static int  SYS_unlink = 7;
  	public final static int  SYS_getpid = 8;
  	public final static int  SYS_kill  =  9;
  	public final static int  SYS_fstat =      10;
  	/*final static int  SYS_sbrk  11 - not currently a system call, but reserved.  */
  	/* ARGV support.  */
  	public final static int  SYS_argvlen= 12;
  	/* These are extras added for one reason or another.  */
  	public final static int  SYS_chdir  =  14;
  	public final static int  SYS_stat   =  15;
  	public final static int  SYS_chmod  =  16;
  	public final static int  SYS_utime  =  17;
  	public final static int  SYS_time   =  18;
  	public final static int  SYS_gettimeofday =19;
  	public final static int  SYS_times  =  20;
  	public final static int  SYS_link   =  21;
  	public final static int  SYS_ftruncate=3000;
  	public final static int  SYS_isatty=3001;
      public void syscall(Sim s) throws CPUException;
      boolean doneContinue();
      public void writeUART(int val);
      public int readUART() throws CPUException;
      public int readFIFO();
      /** notification that the CPU is halted */
  	public void halted();
  	/** notification that the CPU is running */
  	public void running();
      
  }
  