nachos.machine
Class TranslationEntry

java.lang.Object
  nachos.machine.TranslationEntry

public final class TranslationEntry
extends Object

A single translation between a virtual page and a physical page.

Field Summary

boolean	dirty This flag is set to true every time the page is written by a user program.
int	ppn The physical page number.
boolean	readOnly If this flag is true, the user pprogram is not allowed to modify the contents of this virtual page.
boolean	used This flag is set to true every time the page is read or written by a user program.
boolean	valid If this flag is false, this translation entry is ignored.
int	vpn The virtual page number.

Constructor Summary

TranslationEntry()
Allocate a new invalid translation entry.

TranslationEntry(int vpn, int ppn, boolean valid, boolean readOnly, boolean used, boolean dirty)
Allocate a new translation entry with the specified initial state.

TranslationEntry(TranslationEntry entry)
Allocate a new translation entry, copying the contents of an existing one.

Method Summary

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

vpn

public int vpn

The virtual page number.

ppn

public int ppn

The physical page number.

valid

public boolean valid

If this flag is false, this translation entry is ignored.

readOnly

public boolean readOnly

If this flag is true, the user pprogram is not allowed to modify the contents of this virtual page.

used

public boolean used

This flag is set to true every time the page is read or written by a user program.

dirty

public boolean dirty

This flag is set to true every time the page is written by a user program.

Constructor Detail

TranslationEntry

public TranslationEntry()

Allocate a new invalid translation entry.

TranslationEntry

public TranslationEntry(int vpn,
                        int ppn,
                        boolean valid,
                        boolean readOnly,
                        boolean used,
                        boolean dirty)

Allocate a new translation entry with the specified initial state.

Parameters:

vpn - the virtual page numben.

ppn - the physical page number.

valid - the valid bit.

readOnly - the read-only bit.

used - the used bit.

dirty - the dirty bit.

TranslationEntry

public TranslationEntry(TranslationEntry entry)

Allocate a new translation entry, copying the contents of an existing one.

Parameters:

entry - the translation entry to copy.