avrora.sim
Class Segment

java.lang.Object
  avrora.sim.Segment

Direct Known Subclasses:

CodeSegment

public class Segment

extends java.lang.Object

The Segment class represents a segment of byte-addressable memory that supports probing. It is used to represent the SRAM, the flash, and the EEPROM. For efficiency, it sharing of the underlying byte array representing the memory.

Nested Class Summary

class	Segment.AddressOutOfBoundsException The AddressOutOfBoundsException class represents an error when using the get() and set() methods where the user specifies an address that is out of the bounds of the segment.
static interface	Segment.ErrorReporter The ErrorReporter class is used to intercept errors caused by trying to either read or write outside the bounds of this segment.
static interface	Segment.Sharer The Sharer interface must be implemented by a class that needs to share the underlying data representation for efficiency reasons.

Field Summary

protected Segment.ErrorReporter	errorReporter
protected BaseInterpreter	interpreter
protected java.lang.String	name
protected byte[]	segment_data
protected MulticastWatch[]	segment_watches
protected Segment.Sharer	sharer
protected int	size
protected byte	value

Constructor Summary

Segment(java.lang.String name, int size, byte defvalue, BaseInterpreter bi, Segment.ErrorReporter er)
The constructor for the Segment class creates an object that represents this segment.

Method Summary

byte	get(int address) The get() method simply retrieves the value of a byte at a particular location in the segment.
void	insertWatch(int data_addr, Simulator.Watch p) The insertWatch() allows user code to insert a watch on a particular memory location.
byte	read(int address) The read() method of the segment reads a byte from a location in the segment, firing any watches on the address before and after the read.
void	removeWatch(int data_addr, Simulator.Watch p) The removeWatch() removes a watch on a particular memory location.
void	set(int address, byte val) The set() method simply sets the value of a byte at a particular location in the segment.
byte[]	share(Segment.Sharer s) The share() method allows sharing of the underlying array representing the values of memory.
void	write(int address, byte val) The write() method of the segment writes a byte to a location in the segment, firing any watches on the address before and after the write.

Methods inherited from class java.lang.Object

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

Field Detail

interpreter

protected final BaseInterpreter interpreter

name

protected final java.lang.String name

size

protected final int size

value

protected final byte value

segment_data

protected byte[] segment_data

errorReporter

protected final Segment.ErrorReporter errorReporter

segment_watches

protected MulticastWatch[] segment_watches

sharer

protected Segment.Sharer sharer

Constructor Detail

Segment

public Segment(java.lang.String name,
               int size,
               byte defvalue,
               BaseInterpreter bi,
               Segment.ErrorReporter er)

The constructor for the Segment class creates an object that represents this segment. The segment is byte-addressable and allows watches to be placed on individual bytes in memory.

Parameters:

name - the name of the segment as a string

size - the size of the segment in bytes

defvalue - the default value of bytes in this segment

er - an object that is notified when an attempt is made to read or write outside of the bounds of this segment

Method Detail

share

public byte[] share(Segment.Sharer s)

The share() method allows sharing of the underlying array representing the values of memory. This is used for performance.

Parameters:

s - the sharer to allow access to this segment's internal data

Returns:

the byte array that is the underlying representation of the memory

read

public byte read(int address)

The read() method of the segment reads a byte from a location in the segment, firing any watches on the address before and after the read. This is intended to be called ONLY by the interpreter and device implementations, and NOT by other parts of the simulation that simply want to inspect the state of simulation. A call to the read() method will result in a call to the readError() method of the ErrorReporter object associated with this segment if the access is not within the bounds of the segment.

Parameters:

address - the address in the segment from which to read the byte

Returns:

the byte value at this location

get

public byte get(int address)

The get() method simply retrieves the value of a byte at a particular location in the segment. This method will NOT result in triggering any watches installed for this address. This method is intended for use by user code outside of the simulation (such as probes and watches) to inspect the values in this segment.

Parameters:

address - the address in the segment for which to retrieve the value

Returns:

the value of the byte at the specified location, without triggering any monitors on this location

Throws:

Segment.AddressOutOfBoundsException - if the specified address is not within the bounds of this segment

write

public void write(int address,
                  byte val)

The write() method of the segment writes a byte to a location in the segment, firing any watches on the address before and after the write. This is intended to be called ONLY by the interpreter and device implementations, and NOT by other parts of the simulation that want to alter the state of the simulation. A call to the write() method will result in a call to the writeError() method of the ErrorReporter object associated with this segment if the access is not within the bounds of the segment.

Parameters:

address - the address in the segment which should be written

val - the value to write to the location in the segment

set

public void set(int address,
                byte val)

The set() method simply sets the value of a byte at a particular location in the segment. This method will NOT result in triggering any watches installed for this address. This method is intended for use by code outside of the simulation (such as probes and watches) to alter the state of the memory segment, which should not be done by user code.

Parameters:

address - the address in the segment which should be written

val - the value to write to this byte in memory

Throws:

Segment.AddressOutOfBoundsException - if the specified address is not within the bounds of this segment

insertWatch

public void insertWatch(int data_addr,
                        Simulator.Watch p)

The insertWatch() allows user code to insert a watch on a particular memory location. The watch will be triggered when a read() or write() to the memory location occurs in during simulation.

Parameters:

data_addr - the address of the byte in memory for which to insert the watch

p - the watch to insert on the memory byte

removeWatch

public void removeWatch(int data_addr,
                        Simulator.Watch p)

The removeWatch() removes a watch on a particular memory location. The watch will no longer be triggered for subseqent read()s or write()s occur in during simulation. Reference equality is used to match watches, and NOT Object.equals().

Parameters:

data_addr - the address of the byte in memory for which to remove the watch

p - the watch to remove