nachos.machine
Class Coff

java.lang.Object
  nachos.machine.Coff

public class Coff
extends Object

A COFF (common object file format) loader.

Field Summary

protected int	entryPoint The virtual address of the first instruction of the program.
protected CoffSection[]	sections The sections in this COFF executable.

Constructor Summary

protected	Coff() Allocate a new Coff object.
	Coff(OpenFile file) Load the COFF executable in the specified file.

Method Summary

void	close() Close the executable file and release any resources allocated by this loader.
int	getEntryPoint() Return the program entry point.
int	getNumSections() Return the number of sections in the executable.
CoffSection	getSection(int sectionNumber) Return an object that can be used to access the specified section.

Methods inherited from class java.lang.Object

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

Field Detail

entryPoint

protected int entryPoint

The virtual address of the first instruction of the program.

sections

protected CoffSection[] sections

The sections in this COFF executable.

Constructor Detail

Coff

protected Coff()

Allocate a new Coff object.

Coff

public Coff(OpenFile file)
     throws EOFException

Load the COFF executable in the specified file.

Notes:

1. If the constructor returns successfully, the file becomes the property of this loader, and should not be accessed any further.
2. The autograder expects this loader class to be used. Do not load sections through any other mechanism.
3. This loader will verify that the file is backed by a file system, by asserting that read() operations take non-zero simulated time to complete. Do not supply a file backed by a simulated cache (the primary purpose of this restriction is to prevent sections from being loaded instantaneously while handling page faults).

Parameters:

file - the file containing the executable.

Throws:

EOFException - if the executable is corrupt.

Method Detail

getNumSections

public int getNumSections()

Return the number of sections in the executable.

Returns:

the number of sections in the executable.

getSection

public CoffSection getSection(int sectionNumber)

Return an object that can be used to access the specified section. Valid section numbers include 0 through getNumSections() - 1.

Parameters:

sectionNumber - the section to select.

Returns:

an object that can be used to access the specified section.

getEntryPoint

public int getEntryPoint()

Return the program entry point. This is the value that to which the PC register should be initialized to before running the program.

Returns:

the program entry point.

close

public void close()

Close the executable file and release any resources allocated by this loader.