pagetable.java

只是一个简单模拟操作系统

/*
 * PageTable.java
 *
 * Created on 2006年3月15日, 下午9:57
 *
 */

package os.memory;

/**
 *
 * @author Vernkin
 */
import java.util.LinkedList;


/**
 * 页表页，包含程序上下文
 */
public class PageTable
{
	/**
	 * Store the orig-real reflection table
	 */
	private LinkedList store = new LinkedList();
        /**
         * The PSW space(Process Context)
         */
        private int contextPage = 0;//the first index of contextPrt
	/**
	 * A PageTable refers a MyProcess
	 */
	private os.process.MyProcess pro;
	
	/**
	 * Constructor
	 * @param id A new Process
	 * @param context The context space
	 */
	public PageTable(os.process.MyProcess id,int context){
		pro = id;
                contextPage = context;
	}
	
	/**
	 * Whether the param pp is the same as the pro in thisPageTable
	 * @param pp other Process
	 * @return whether the param pp is the same as the pro in thisPageTable
	 */
	public boolean sameProcess(os.process.MyProcess pp){
            return pro == pp;
        }
	
	/**
	 * 看该物理页是否 属于该进程
	 * @param page the physical page
	 * @return whether this physical page belongs to this process
	 */
	public boolean isBelonged(int page){
		PageUnit pu;
		for(int i=0;i<store.size();i++){
			pu = (PageUnit)store.get(i);
			if(pu.real == page)
				return true;
		}
		return false;
	}
	
	
	/**
	 * get all the momory page that current process occupied
	 * including the context page
	 * @return all the momory page that current process occupied
	 */
	public int[] getAllUsedPage(){
            int[] ret = new int[store.size()+1];	
            for(int i=0;i<store.size();i++){
		ret[i] = ((PageUnit)store.get(i)).real;
            }
            ret[store.size()] = contextPage;
            return ret;
	}
	
	/**
	 * Get the process ID
	 * @return process ID
	 */
	public int getID(){
            return pro.getID();	
	}
	
	
	/**
	 * add a new orig-real pair to store
	 * @param orig logic page
	 * @param real physical page
	 */
	public void add(int orig,int real){
   //         System.out.println(pro+" orig: "+orig+" real: "+real);
            store.add(new PageUnit(orig,real));
	}
	
	
	/**获得逻辑页数对应的物理页数**/
	/**
	 * Get the real page indicate by a logic page
	 * @param orig the logic page
	 * @return the physical page
	 */
	public int getPhysicalPage(int orig){
		PageUnit pu;
		for(int i=0;i<store.size();i++){
			pu = (PageUnit)store.get(i);
			if(pu.orig == orig)
				return pu.real;
		}
		return -1;
	}
        
        
        /**
         * Get the process context page
         * @return the process context page
         */
        public int getContextPage(){
            return contextPage;
        }
        
        public int getSize(){
            return store.size() + 1;
        }
        
        
        public os.process.MyProcess getProcess(){
            return pro;
        }



	/**
	 * A base page unit
	 */
	private class PageUnit{
		int orig = -1;
		int real = -1;
		private PageUnit(int orig,int real){
			this.orig = orig;
			this.real = real;
		}
		
		/**
		 * convert to String form
		 */
		public String toString(){
			return "Orig "+orig+" :Real "+real;
		}
		
	}
}