avrora.sim
Class CodeSegment

java.lang.Object
  avrora.sim.Segment
      avrora.sim.CodeSegment

Direct Known Subclasses:

ReprogrammableCodeSegment

public class CodeSegment

extends Segment

The CodeSegment class represents a segment of memory that stores executable code. The program memory on the AVR chips, for example, is a flash segment.

Nested Class Summary

static interface	CodeSegment.CodeSharer The CodeSharer interface is used to allow sharing of the underlying array representing the code.
static class	CodeSegment.DefaultFactory The DefaultFactory class represents a factory capable of creating a simple code segment that is not reprogrammable.
static interface	CodeSegment.Factory The CodeSegment.Factory class is used to create a new code segment for a new interpreter.
protected class	CodeSegment.ProbedInstr The ProbedInstr class represents a wrapper around an instruction in the program that executes the probes before executing the instruction and after the instruction.

Nested classes inherited from class avrora.sim.Segment

Segment.AddressOutOfBoundsException, Segment.ErrorReporter, Segment.Sharer

Field Summary

protected CodeSegment.CodeSharer	codeSharer
static byte	DEFAULT_VALUE The DEFAULT_VALUE field stores the default value that is used to initialize the flash memory.
protected avrora.sim.CodeSegment.MisalignedInstr	MISALIGNED_INSTR
protected avrora.sim.CodeSegment.NoInstr	NO_INSTR
protected Instr[]	segment_instr The segment_instr field stores a reference to an array that contains the disassembled instructions that correspond to the machine code.

Fields inherited from class avrora.sim.Segment

errorReporter, interpreter, name, segment_data, segment_watches, sharer, size, value

Constructor Summary

CodeSegment(java.lang.String name, int size, BaseInterpreter bi, Segment.ErrorReporter er)
The constructor for the CodeSegment class creates a new code segment, complete with binary and instruction representations.

Method Summary

Instr	getInstr(int address) The getInstr() method reads an Instr from the specified address in the flash.
void	insertProbe(int address, Simulator.Probe p) The insertProbe() method inserts a probe on an instruction at the specified address.
void	load(Program p) The load() method loads a program into the flash memory, writing the binary machine code and the disassembled instructions.
Instr	readInstr(int address) The readInstr() method reads an Instr from the specified address in the flash.
void	removeProbe(int address, Simulator.Probe p) The removeProbe() method removes a probe from a particular instruction in the program.
protected void	replaceInstr(int address, Instr i) The replaceInstr() method is used internally to update an instruction in the flash segment without losing all of its attached instrumentation (i.e. probes and watches).
Instr[]	shareCode(CodeSegment.CodeSharer s)
void	update() The update() method is called when the program attempts an update to the flash memory through the SPM instruction.
protected void	writeInstr(int address, Instr i)

Methods inherited from class avrora.sim.Segment

get, insertWatch, read, removeWatch, set, share, write

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_VALUE

public static final byte DEFAULT_VALUE

The DEFAULT_VALUE field stores the default value that is used to initialize the flash memory.

See Also:

Constant Field Values

segment_instr

protected Instr[] segment_instr

The segment_instr field stores a reference to an array that contains the disassembled instructions that correspond to the machine code.

NO_INSTR

protected final avrora.sim.CodeSegment.NoInstr NO_INSTR

MISALIGNED_INSTR

protected final avrora.sim.CodeSegment.MisalignedInstr MISALIGNED_INSTR

codeSharer

protected CodeSegment.CodeSharer codeSharer

Constructor Detail

CodeSegment

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

The constructor for the CodeSegment class creates a new code segment, complete with binary and instruction representations.

Parameters:

name - the name of the segment as a string

size - the size of the segment in bytes

bi - the interpreter that will use this segment

er - the error reporter consulted on accesses out of bounds

Method Detail

replaceInstr

protected void replaceInstr(int address,
                            Instr i)

The replaceInstr() method is used internally to update an instruction in the flash segment without losing all of its attached instrumentation (i.e. probes and watches).

Parameters:

address - the address in the code segment of the instruction

i - the new instruction to place at this location in the flash

update

public void update()

The update() method is called when the program attempts an update to the flash memory through the SPM instruction. This is only supported on some flash memory types.

shareCode

public Instr[] shareCode(CodeSegment.CodeSharer s)

load

public void load(Program p)

The load() method loads a program into the flash memory, writing the binary machine code and the disassembled instructions. This should only be done once for a FlashMemory object, before any instrumentation is added.

Parameters:

p - the program to be loaded into the flash memory

readInstr

public Instr readInstr(int address)

The readInstr() method reads an Instr from the specified address in the flash. For misaligned accesses and accesses to places in the flash where there are no valid instructions, this method returns null. This method does not return ProbedInstr or DisassembleInstr objects which are used internally to accomplish probing and dynamically updated code.

Parameters:

address - the address in the flash from which to read the instruction

Returns:

a reference to the Instr object at this address in the flash; null if there is no instruction at this address.

getInstr

public Instr getInstr(int address)

The getInstr() method reads an Instr from the specified address in the flash. For misaligned accesses and accesses to places in the flash where there are no valid instructions, this method may return instances of MisalignedInstr or DisassembleInstr objects which are used internally to check for errors and support dynamically updated code. Additionally, this method may return instances of ProbedInstr that are used internally to support probing of instructions.

Parameters:

address - the address in the flash from which to read the instruction

Returns:

a reference to the Instr object at this address in the flash; null if there is no instruction at this address.

insertProbe

public void insertProbe(int address,
                        Simulator.Probe p)

The insertProbe() method inserts a probe on an instruction at the specified address. No equality testing is done; i.e. inserting the same probe on the same address more than once will result in it being triggered more than once when the instruction executes.

Parameters:

address - the address of the instruction on which to insert the probe

p - the probe to insert on this instruction

removeProbe

public void removeProbe(int address,
                        Simulator.Probe p)

The removeProbe() method removes a probe from a particular instruction in the program. The probe will no longer be triggered for subsequent executions of this instruction. Reference equality is used for testing whether the probe should be removed; i.e. the Object.equals() method is not consulted.

Parameters:

address - the address of the instructiobn on which to insert the probe

p - the probe to isnert on this instruction

writeInstr

protected void writeInstr(int address,
                          Instr i)