nachos.machine
Class TranslationEntry

java.lang.Object
  extended by nachos.machine.TranslationEntry

public final class TranslationEntry
extends java.lang.Object

This class defines an entry in a translation table -- either in a page table or a TLB. Each entry defines a mapping from one virtual page to one physical page. In addition, there are some extra bits for access control (valid and read-only) and some bits for usage information (use and dirty).


Field Summary
 boolean dirty
          This bit is set by the hardware every time the page is modified.
 int physicalPage
          The page number in real memory (relative to the start of "mainMemory")
 boolean readOnly
          If this bit is set, the user program is not allowed to modify the contents of the page.
 boolean use
          This bit is set by the hardware every time the page is referenced or modified.
 boolean valid
          If this bit is not set, the translation is ignored.
 int virtualPage
          The page number in virtual memory.
 
Constructor Summary
TranslationEntry()
           
 
Method Summary
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

virtualPage

public int virtualPage
The page number in virtual memory.


physicalPage

public int physicalPage
The page number in real memory (relative to the start of "mainMemory")


valid

public boolean valid
If this bit is not set, the translation is ignored. (In other words, the entry hasn't been initialized.)


readOnly

public boolean readOnly
If this bit is set, the user program is not allowed to modify the contents of the page.


use

public boolean use
This bit is set by the hardware every time the page is referenced or modified.


dirty

public boolean dirty
This bit is set by the hardware every time the page is modified.

Constructor Detail

TranslationEntry

public TranslationEntry()