avrora.sim
Class BaseInterpreter

java.lang.Object
  avrora.sim.BaseInterpreter

All Implemented Interfaces:

InstrVisitor, IORegisterConstants, State

Direct Known Subclasses:

GenInterpreter

public abstract class BaseInterpreter

extends java.lang.Object

implements State, InstrVisitor

The BaseInterpreter class represents a base class of the legacy interpreter and the generated interpreter(s) that stores the state of the executing program, e.g. registers and flags, etc.

Nested Class Summary

class	BaseInterpreter.AddressOutOfBoundsException
class	BaseInterpreter.NoSuchInstructionException
class	BaseInterpreter.PCAlignmentException
class	BaseInterpreter.PCOutOfBoundsException

Nested classes inherited from class avrora.sim.State

State.IOReg, State.RWIOReg

Field Summary

boolean	C
protected MainClock	clock
int	cyclesConsumed The cyclesConsumed field stores the number of cycles consumed in doing a part of the simulation (e.g. executing an instruction or processing an interrupt).
protected long	delayCycles The delayCycles field tracks the number of cycles that the microcontroller is delayed.
protected byte[]	flash_data
protected Instr[]	flash_instr
protected MulticastProbe	globalProbe The activeProbe field stores a reference to a MulticastProbe that contains all of the probes to be fired before and after the main execution runLoop--i.e. before and after every instruction.
boolean	H
boolean	I
protected boolean	innerLoop The innerLoop field is a boolean that is used internally in the implementation of the interpreter.
protected State.IOReg[]	ioregs
boolean	justReturnedFromInterrupt The justReturnedFromInterrupt field is used internally in maintaining the invariant stated in the hardware manual that at least one instruction following a return from an interrupt is executed before another interrupt can be processed.
boolean	N
int	nextPC The nextPC field is used internally in maintaining the correct execution order of the instructions.
protected int	pc
protected long	postedInterrupts
byte[]	regs
boolean	S
protected boolean	shouldRun The shouldRun flag is used internally in the main execution runLoop to implement the correct semantics of start() and stop() to the clients.
protected Simulator	simulator The simulator field stores a reference to the simulator that this interpreter instance corresponds to.
protected boolean	sleeping The sleeping flag is used internally in the simulator when the microcontroller enters the sleep mode.
protected byte[]	sram
protected int	sram_max
protected MulticastWatch[]	sram_probes
protected int	sram_start
protected State.IOReg	SREG_reg
boolean	T
boolean	V
boolean	Z

Fields inherited from interface avrora.sim.State

RESERVED

Fields inherited from interface avrora.sim.IORegisterConstants

ACSR, ADCH, ADCL, ADCSRA, ADMUX, ASSR, DDRA, DDRB, DDRC, DDRD, DDRE, DDRF, DDRG, EEARH, EEARL, EECR, EEDR, EICRA, EICRB, EIFR, EIMSK, ETIFR, ETIMSK, ICR1H, ICR1L, ICR3H, ICR3L, MCUCR, MCUCSR, NUM_REGS, OCDR, OCR0, OCR1AH, OCR1AL, OCR1BH, OCR1BL, OCR1CH, OCR1CL, OCR2, OCR3AH, OCR3AL, OCR3BH, OCR3BL, OCR3CH, OCR3CL, OSCCAL, PINA, PINB, PINC, PIND, PINE, PINF, PING, PORTA, PORTB, PORTC, PORTD, PORTE, PORTF, PORTG, RAMPZ, SFIOR, SPCR, SPDR, SPH, SPL, SPMCSR, SPSR, SREG, SREG_C, SREG_H, SREG_I, SREG_N, SREG_S, SREG_T, SREG_V, SREG_Z, TCCR0, TCCR1A, TCCR1B, TCCR1C, TCCR2, TCCR3A, TCCR3B, TCCR3C, TCNT0, TCNT1H, TCNT1L, TCNT2, TCNT3H, TCNT3L, TIFR, TIMSK, TWAR, TWBR, TWCR, TWDR, TWSR, UBRR0H, UBRR0L, UBRR1H, UBRR1L, UCSR0A, UCSR0B, UCSR0C, UCSR1A, UCSR1B, UCSR1C, UDR0, UDR1, WDTCR, XDIV, XMCRA, XMCRB

Constructor Summary

BaseInterpreter(Simulator simulator, Program p, int flash_size, int ioreg_size, int sram_size)

Method Summary

protected void	advanceCycles(long delta)
protected void	commit()
protected void	delay(long cycles)
void	disableInterrupts()
void	enableInterrupts()
Instr	getCurrentInstr() The getCurrentInstr() method reads the instruction at the current program counter value (PC).
long	getCycles() The getCycles() method returns the clock cycle count recorded so far in the simulation.
byte	getDataByte(int address) The getDataByte() method reads a byte value from the data memory (SRAM) at the specified address.
boolean	getFlag_C() The getFlag_C() method returns the current value of the C bit in the status register as a boolean.
boolean	getFlag_H() The getFlag_H() method returns the current value of the H bit in the status register as a boolean.
boolean	getFlag_I() The getFlag_I() method returns the current value of the I bit in the status register as a boolean.
boolean	getFlag_N() The getFlag_N() method returns the current value of the N bit in the status register as a boolean.
boolean	getFlag_S() The getFlag_S() method returns the current value of the S bit in the status register as a boolean.
boolean	getFlag_T() The getFlag_T() method returns the current value of the T bit in the status register as a boolean.
boolean	getFlag_V() The getFlag_V() method returns the current value of the V bit in the status register as a boolean.
boolean	getFlag_Z() The getFlag_Z() method returns the current value of the Z bit in the status register as a boolean.
Instr	getInstr(int address) The getInstr() can be used to retrieve a reference to the Instr object representing the instruction at the specified program address.
int	getInstrSize(int npc) The getInstrSize() method reads the size of the instruction at the given program address.
State.IOReg	getIOReg(int ioreg) The getIOReg() method is used to retrieve a reference to the actual IOReg instance stored internally in the state.
byte	getIORegisterByte(int ioreg) The getIORegisterByte() method reads the value of an IO register.
int	getPC() The getPC() retrieves the current program counter.
long	getPostedInterrupts() The getPostedInterrupts() method returns a mask that represents all interrupts that are currently pending (meaning they are ready to be fired in priority order as long as the I flag is on).
protected avrora.sim.BaseInterpreter.ProbedInstr	getProbedInstr(int addr)
byte	getProgramByte(int address) The getProgramByte() method reads a byte value from the program (Flash) memory.
byte	getRegisterByte(int reg)
byte	getRegisterByte(Register reg) Read a general purpose register's current value as a byte.
int	getRegisterUnsigned(int reg)
int	getRegisterUnsigned(Register reg) Read a general purpose register's current value as an integer, without any sign extension.
int	getRegisterWord(int reg)
int	getRegisterWord(Register reg) Read a general purpose register pair as an unsigned word.
int	getSP() The getSP() method reads the current value of the stack pointer.
byte	getSREG() The getSREG() method reads the value of the status register.
byte	getStackByte() The getStackByte() method reads a byte from the address specified by SP+1.
protected void	initializeIORegs()
protected void	insertBreakPoint(int addr)
void	insertProbe(Simulator.Probe p) The insertProbe() method allows a probe to be inserted that is executed before and after every instruction that is executed by the simulator
protected void	insertProbe(Simulator.Probe p, int addr)
protected void	insertWatch(Simulator.Watch p, int data_addr)
boolean	isSleeping() The isSleeping() method returns whether the simulator is currently in a sleep mode.
protected void	makeImpression(Program p)
protected avrora.sim.BaseInterpreter.ProbedInstr	makeProbedInstr(int addr)
byte	popByte() The popByte() method pops a byte from the stack by reading from the address pointed to by SP+1 and incrementing the stack pointer.
void	postInterrupt(int num) The postInterrupt() method is generally only used within the simulator which does pre-processing of interrupts before it posts them into the internal State instance.
void	pushByte(byte val) The pushByte() method pushes a byte onto the stack by writing to the memory address pointed to by the stack pointer and decrementing the stack pointer.
protected void	removeBreakPoint(int addr)
void	removeProbe(Simulator.Probe b) The removeProbe() method removes a probe from the global probe table (the probes executed before and after every instruction).
protected void	removeProbe(Simulator.Probe p, int addr)
protected void	removeWatch(Simulator.Watch p, int data_addr)
protected abstract void	runLoop()
void	setDataByte(int address, byte val) The setDataByte() method writes a value to the data memory (SRAM) of the state.
protected void	setInstr(Instr i, int address)
void	setIOReg(int ioreg, State.IOReg reg) The setIOReg method installs the specified IOReg object to the specified IO register number.
void	setIORegisterByte(int ioreg, byte val) The setIORegisterByte() method writes a value to the specified IO register.
void	setPostedInterrupts(long posted)
void	setRegisterByte(int reg, byte val)
protected void	setRegisterByte(Register reg, byte val) The setRegisterByte() method writes a value to a general purpose register.
void	setRegisterWord(int reg, int val)
protected void	setRegisterWord(Register reg, int val) The setRegisterWord method writes a word value to a general purpose register pair.
protected void	setSP(int val) The setSP() method updates the value of the stack pointer.
protected void	setSREG(byte val) The setSREG() method writes the value of the status register.
protected void	start()
void	stop()
void	unpostInterrupt(int num) The unpostInterrupt() method is generally only used within the simulator which does pre-processing of interrupts before it posts them into the internal State instance.

Methods inherited from class java.lang.Object

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

Methods inherited from interface avrora.core.InstrVisitor

visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit

Field Detail

pc

protected int pc

regs

public final byte[] regs

ioregs

protected final State.IOReg[] ioregs

sram

protected byte[] sram

sram_probes

protected MulticastWatch[] sram_probes

flash_instr

protected Instr[] flash_instr

flash_data

protected byte[] flash_data

postedInterrupts

protected long postedInterrupts

sram_start

protected final int sram_start

sram_max

protected final int sram_max

I

public boolean I

T

public boolean T

H

public boolean H

S

public boolean S

V

public boolean V

N

public boolean N

Z

public boolean Z

C

public boolean C

SREG_reg

protected State.IOReg SREG_reg

globalProbe

protected final MulticastProbe globalProbe

The activeProbe field stores a reference to a MulticastProbe that contains all of the probes to be fired before and after the main execution runLoop--i.e. before and after every instruction.

innerLoop

protected boolean innerLoop

The innerLoop field is a boolean that is used internally in the implementation of the interpreter. When something in the simulation changes (e.g. an interrupt is posted), this field is set to false, and the execution loop (e.g. an interpretation or sleep loop) is broken out of.

nextPC

public int nextPC

The nextPC field is used internally in maintaining the correct execution order of the instructions.

cyclesConsumed

public int cyclesConsumed

The cyclesConsumed field stores the number of cycles consumed in doing a part of the simulation (e.g. executing an instruction or processing an interrupt).

delayCycles

protected long delayCycles

The delayCycles field tracks the number of cycles that the microcontroller is delayed. Delay is needed because some devices pause execution of the program for some number of cycles, and also to implement random delay at the beginning of startup in multiple node scenarios to prevent artificial cycle-level synchronization.

shouldRun

protected boolean shouldRun

The shouldRun flag is used internally in the main execution runLoop to implement the correct semantics of start() and stop() to the clients.

sleeping

protected boolean sleeping

The sleeping flag is used internally in the simulator when the microcontroller enters the sleep mode.

justReturnedFromInterrupt

public boolean justReturnedFromInterrupt

The justReturnedFromInterrupt field is used internally in maintaining the invariant stated in the hardware manual that at least one instruction following a return from an interrupt is executed before another interrupt can be processed.

simulator

protected final Simulator simulator

The simulator field stores a reference to the simulator that this interpreter instance corresponds to. There should be a one-to-one mapping between instances of the Simulator class and instances of the BaseInterpreter class.

clock

protected final MainClock clock

Constructor Detail

BaseInterpreter

public BaseInterpreter(Simulator simulator,
                       Program p,
                       int flash_size,
                       int ioreg_size,
                       int sram_size)

Method Detail

makeImpression

protected void makeImpression(Program p)

start

protected void start()

stop

public void stop()

runLoop

protected abstract void runLoop()

insertProbe

protected void insertProbe(Simulator.Probe p,
                           int addr)

insertProbe

public void insertProbe(Simulator.Probe p)

The insertProbe() method allows a probe to be inserted that is executed before and after every instruction that is executed by the simulator

Parameters:

p - the probe to insert

removeProbe

protected void removeProbe(Simulator.Probe p,
                           int addr)

removeProbe

public void removeProbe(Simulator.Probe b)

The removeProbe() method removes a probe from the global probe table (the probes executed before and after every instruction). The comparison used is reference equality, not .equals().

Parameters:

b - the probe to remove

insertBreakPoint

protected void insertBreakPoint(int addr)

removeBreakPoint

protected void removeBreakPoint(int addr)

insertWatch

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

removeWatch

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

initializeIORegs

protected void initializeIORegs()

advanceCycles

protected void advanceCycles(long delta)

delay

protected void delay(long cycles)

getRegisterByte

public byte getRegisterByte(int reg)

getRegisterUnsigned

public int getRegisterUnsigned(int reg)

getRegisterWord

public int getRegisterWord(int reg)

getRegisterByte

public byte getRegisterByte(Register reg)

Read a general purpose register's current value as a byte.

Specified by:

getRegisterByte in interface State

Parameters:

reg - the register to read

Returns:

the current value of the register

getRegisterUnsigned

public int getRegisterUnsigned(Register reg)

Read a general purpose register's current value as an integer, without any sign extension.

Specified by:

getRegisterUnsigned in interface State

Parameters:

reg - the register to read

Returns:

the current unsigned value of the register

getRegisterWord

public int getRegisterWord(Register reg)

Read a general purpose register pair as an unsigned word. This method will read the value of the specified register and the value of the next register in numerical order and return the two values combined as an unsigned integer The specified register should be less than r31, because r32 (the next register) does not exist.

Specified by:

getRegisterWord in interface State

Parameters:

reg - the low register of the pair to read

Returns:

the current unsigned word value of the register pair

setRegisterByte

protected void setRegisterByte(Register reg,
                               byte val)

The setRegisterByte() method writes a value to a general purpose register. This is a destructive update and should only be called from the appropriate places in the simulator.

Parameters:

reg - the register to write the value to

val - the value to write to the register

setRegisterWord

protected void setRegisterWord(Register reg,
                               int val)

The setRegisterWord method writes a word value to a general purpose register pair. This is a destructive update and should only be called from the appropriate places in the simulator. The specified register and the next register in numerical order are updated with the low-order and high-order byte of the value passed, respectively. The specified register should be less than r31, since r32 (the next register) does not exist.

Parameters:

reg - the low register of the pair to write

val - the word value to write to the register pair

setRegisterByte

public void setRegisterByte(int reg,
                            byte val)

setRegisterWord

public void setRegisterWord(int reg,
                            int val)

getSREG

public byte getSREG()

The getSREG() method reads the value of the status register. The status register contains the I, T, H, S, V, N, Z, and C flags, in order from highest-order to lowest-order.

Specified by:

getSREG in interface State

Returns:

the value of the status register as a byte.

setSREG

protected void setSREG(byte val)

The setSREG() method writes the value of the status register. This method should only be called from the appropriate places in the simulator.

Parameters:

val -

getDataByte

public byte getDataByte(int address)

The getDataByte() method reads a byte value from the data memory (SRAM) at the specified address.

Specified by:

getDataByte in interface State

Parameters:

address - the byte address to read

Returns:

the value of the data memory at the specified address

Throws:

java.lang.ArrayIndexOutOfBoundsException - if the specified address is not the valid memory range

getProgramByte

public byte getProgramByte(int address)

The getProgramByte() method reads a byte value from the program (Flash) memory. The flash memory generally stores read-only values and the instructions of the program. Care should be taken that the program memory at the specified address does not contain an instruction. This is because, in general, programs should not read instructions as data, and secondly, because no assembler is present in Avrora and therefore the actual byte value of an instruction may not be known.

Specified by:

getProgramByte in interface State

Parameters:

address - the byte address at which to read

Returns:

the byte value of the program memory at the specified address

Throws:

java.lang.ArrayIndexOutOfBoundsException - if the specified address is not the valid program memory range

setDataByte

public void setDataByte(int address,
                        byte val)

The setDataByte() method writes a value to the data memory (SRAM) of the state. This is generally meant for the simulator, related classes, and device implementations to use, but could also be used by debuggers and other tools.

Parameters:

address - the byte address at which to write the value

val - the value to write

getCurrentInstr

public Instr getCurrentInstr()

The getCurrentInstr() method reads the instruction at the current program counter value (PC).

Returns:

a reference to the Instr representing the instruction at the current program counter value

getInstrSize

public int getInstrSize(int npc)

The getInstrSize() method reads the size of the instruction at the given program address. This is needed in the interpreter to compute the target of a skip instruction (an instruction that skips over the instruction following it).

Parameters:

npc - the program address of the instruction

Returns:

the size in bytes of the instruction at the specified program address

getIORegisterByte

public byte getIORegisterByte(int ioreg)

The getIORegisterByte() method reads the value of an IO register. Invocation of this method causes an invocatiobn of the .read() method on the corresponding internal IOReg object, and its value returned.

Specified by:

getIORegisterByte in interface State

Parameters:

ioreg - the IO register number

Returns:

the value of the IO register

setIOReg

public void setIOReg(int ioreg,
                     State.IOReg reg)

The setIOReg method installs the specified IOReg object to the specified IO register number. This method is generally only used in the simulator and in device implementations to set up the state correctly during initialization.

Parameters:

ioreg - the IO register number

reg - the IOReg object to install

getIOReg

public State.IOReg getIOReg(int ioreg)

The getIOReg() method is used to retrieve a reference to the actual IOReg instance stored internally in the state. This is generally only used in the simulator and device implementations, and clients should probably not call this memory directly.

Specified by:

getIOReg in interface State

Parameters:

ioreg - the IO register number to retrieve

Returns:

a reference to the IOReg instance of the specified IO register

setIORegisterByte

public void setIORegisterByte(int ioreg,
                              byte val)

The setIORegisterByte() method writes a value to the specified IO register. This is generally only used internally to the simulator and device implementations, and client interfaces should probably not call this method.

Parameters:

ioreg - the IO register number to which to write the value

val - the value to write to the IO register

popByte

public byte popByte()

The popByte() method pops a byte from the stack by reading from the address pointed to by SP+1 and incrementing the stack pointer. This method, like all of the other methods that change the state, should probably only be used within the simulator. This method should not be called with an empty stack, as it will cause an exception consistent with trying to read non-existent memory.

Returns:

the value on the top of the stack

pushByte

public void pushByte(byte val)

The pushByte() method pushes a byte onto the stack by writing to the memory address pointed to by the stack pointer and decrementing the stack pointer. This method, like all of the other methods that change the state, should probably only be used within the simulator.

Parameters:

val - the value to push onto the stack

setSP

protected void setSP(int val)

The setSP() method updates the value of the stack pointer. Generally the stack pointer is stored in two IO registers SPL and SPH. This method should generally only be used within the simulator.

Parameters:

val -

See Also:

IORegisterConstants

getCycles

public long getCycles()

The getCycles() method returns the clock cycle count recorded so far in the simulation.

Specified by:

getCycles in interface State

Returns:

the number of clock cycles elapsed in the simulation

getPostedInterrupts

public long getPostedInterrupts()

The getPostedInterrupts() method returns a mask that represents all interrupts that are currently pending (meaning they are ready to be fired in priority order as long as the I flag is on).

Specified by:

getPostedInterrupts in interface State

Returns:

a mask representing the interrupts which are posted for processing

getPC

public int getPC()

The getPC() retrieves the current program counter.

Specified by:

getPC in interface State

Returns:

the program counter as a byte address

getFlag_I

public boolean getFlag_I()

The getFlag_I() method returns the current value of the I bit in the status register as a boolean.

Specified by:

getFlag_I in interface State

Returns:

the value of the flag

getFlag_T

public boolean getFlag_T()

The getFlag_T() method returns the current value of the T bit in the status register as a boolean.

Specified by:

getFlag_T in interface State

Returns:

the value of the flag

getFlag_H

public boolean getFlag_H()

The getFlag_H() method returns the current value of the H bit in the status register as a boolean.

Specified by:

getFlag_H in interface State

Returns:

the value of the flag

getFlag_S

public boolean getFlag_S()

The getFlag_S() method returns the current value of the S bit in the status register as a boolean.

Specified by:

getFlag_S in interface State

Returns:

the value of the flag

getFlag_V

public boolean getFlag_V()

The getFlag_V() method returns the current value of the V bit in the status register as a boolean.

Specified by:

getFlag_V in interface State

Returns:

the value of the flag

getFlag_N

public boolean getFlag_N()

The getFlag_N() method returns the current value of the N bit in the status register as a boolean.

Specified by:

getFlag_N in interface State

Returns:

the value of the flag

getFlag_Z

public boolean getFlag_Z()

The getFlag_Z() method returns the current value of the Z bit in the status register as a boolean.

Specified by:

getFlag_Z in interface State

Returns:

the value of the flag

getFlag_C

public boolean getFlag_C()

The getFlag_C() method returns the current value of the C bit in the status register as a boolean.

Specified by:

getFlag_C in interface State

Returns:

the value of the flag

getInstr

public Instr getInstr(int address)

The getInstr() can be used to retrieve a reference to the Instr object representing the instruction at the specified program address. Care should be taken that the address in program memory specified does not contain data. This is because Avrora does have a functioning disassembler and assumes that the Instr objects for each instruction in the program are known a priori.

Specified by:

getInstr in interface State

Parameters:

address - the byte address from which to read the instruction

Returns:

a reference to the Instr object representing the instruction at that address in the program

setInstr

protected void setInstr(Instr i,
                        int address)

getStackByte

public byte getStackByte()

The getStackByte() method reads a byte from the address specified by SP+1. This method should not be called with an empty stack, as it will cause an exception consistent with trying to read non-existent memory.

Specified by:

getStackByte in interface State

Returns:

the value on the top of the stack

getSP

public int getSP()

The getSP() method reads the current value of the stack pointer. Since the stack pointer is stored in two IO registers, this method will cause the invocation of the .read() method on each of the IOReg objects that store these values.

Specified by:

getSP in interface State

Returns:

the value of the stack pointer as a byte address

isSleeping

public boolean isSleeping()

The isSleeping() method returns whether the simulator is currently in a sleep mode.

Specified by:

isSleeping in interface State

Returns:

true if the simulator is in a sleep mode; false otherwise

unpostInterrupt

public void unpostInterrupt(int num)

The unpostInterrupt() method is generally only used within the simulator which does pre-processing of interrupts before it posts them into the internal State instance. This method causes the specified interrupt number to be removed from the pending list of interrupts Clients should not use this method directly.

Parameters:

num - the interrupt number to post

setPostedInterrupts

public void setPostedInterrupts(long posted)

postInterrupt

public void postInterrupt(int num)

The postInterrupt() method is generally only used within the simulator which does pre-processing of interrupts before it posts them into the internal State instance. This method causes the specified interrupt number to be added to the pending list of interrupts Clients should not use this method directly.

Parameters:

num - the interrupt number to post

enableInterrupts

public void enableInterrupts()

disableInterrupts

public void disableInterrupts()

getProbedInstr

protected avrora.sim.BaseInterpreter.ProbedInstr getProbedInstr(int addr)

makeProbedInstr

protected avrora.sim.BaseInterpreter.ProbedInstr makeProbedInstr(int addr)

commit

protected void commit()