de.michab.simulator.mos6502
Class Cpu6510

java.lang.Object
  de.michab.simulator.DefaultChip
      de.michab.simulator.mos6502.Cpu6510

All Implemented Interfaces:

Addressable, Chip, Processor

public class Cpu6510

extends DefaultChip

implements Processor

Implements a MOS6510 processor as built into the C64. For the implementation the following documentation was used:

• http://www.6502.org/tutorials/6502opcodes.htm
• www.digitpress.com/the_digs/vic20/melick/6502b.txt

Version:

$Revision: 1.37 $

Author:

Michael Binz

Field Summary

static int	IRQ_VECTOR
static int	NMI_VECTOR
static int	RESET_VECTOR Processor specific constants.
static int	STATUS_FLAG_BREAK
static int	STATUS_FLAG_CARRY
static int	STATUS_FLAG_DECIMAL
static int	STATUS_FLAG_INTERRUPT
static int	STATUS_FLAG_NEGATIVE
static int	STATUS_FLAG_OVERFLOW
static int	STATUS_FLAG_ZERO

Fields inherited from interface de.michab.simulator.Processor

BIT_0, BIT_1, BIT_2, BIT_3, BIT_4, BIT_5, BIT_6, BIT_7, BIT_8, DEC_0, DEC_1, DEC_2, DEC_3, DEC_4, DEC_5, DEC_6, DEC_7, DEC_8, DEC_9

Constructor Summary

Cpu6510(Memory mem, Clock clock)
Create a processor tied to the passed memory.

Method Summary

int	getAccu() Read the accu.
Memory	getMemory() Get the Memory this CPU is attached to.
int	getPC() Read the program counter.
Port[]	getPorts() Get this processors ports.
byte	getStatusRegister() Get our status flags into a byte value.
int	getX() Read the x register.
int	getY() Read the y register.
void	IRQ() Handles the IRQ interrupt.
boolean	isStatusFlagSet(int statusEnum) Test a single status register flag.
void	NMI() Handles the NMI interrupt.
byte	read(int i) Read this processor's ports.
void	reset() Initialises the program counter from the reset vector.
void	setAccu(int a) Sets the accu register.
void	setDebugger(Debugger d) Sets a debugger on this processor instance.
void	setPC(int pc) Set the program counter to a new address.
void	setPortListener(int portId, Forwarder listener) Sets a listener on the passed port.
void	setStatusRegister(byte status) Set our status flags from a byte value.
void	setX(int x) Sets the x register.
void	setY(int y) Sets the y register.
void	stealCycles(int count) experimental TODO
java.lang.String	toString() Returns a string representation of this processor for debug purposes.
void	write(int i, byte b) Write this processor's ports.

Methods inherited from class de.michab.simulator.DefaultChip

createPorts

Methods inherited from class java.lang.Object

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

Field Detail

STATUS_FLAG_CARRY

public static final int STATUS_FLAG_CARRY

See Also:

Constant Field Values

STATUS_FLAG_ZERO

public static final int STATUS_FLAG_ZERO

See Also:

Constant Field Values

STATUS_FLAG_INTERRUPT

public static final int STATUS_FLAG_INTERRUPT

See Also:

Constant Field Values

STATUS_FLAG_DECIMAL

public static final int STATUS_FLAG_DECIMAL

See Also:

Constant Field Values

STATUS_FLAG_BREAK

public static final int STATUS_FLAG_BREAK

See Also:

Constant Field Values

STATUS_FLAG_OVERFLOW

public static final int STATUS_FLAG_OVERFLOW

See Also:

Constant Field Values

STATUS_FLAG_NEGATIVE

public static final int STATUS_FLAG_NEGATIVE

See Also:

Constant Field Values

RESET_VECTOR

public static final int RESET_VECTOR

Processor specific constants.

See Also:

Constant Field Values

IRQ_VECTOR

public static final int IRQ_VECTOR

See Also:

Constant Field Values

NMI_VECTOR

public static final int NMI_VECTOR

See Also:

Constant Field Values

Constructor Detail

Cpu6510

public Cpu6510(Memory mem,
               Clock clock)

Create a processor tied to the passed memory. Note that this memory has to contain some valid instruction sequences. Especially a valid reset vector has to be included to successfully start the emulation.

Parameters:

mem - The memory to attach to the new processor instance.

clock - A reference to the system clock.

Method Detail

getMemory

public Memory getMemory()

Get the Memory this CPU is attached to.

Returns:

The Memory this CPU is attached to.

write

public void write(int i,
                  byte b)

Write this processor's ports.

Specified by:

write in interface Addressable

Parameters:

i - The port number to write.

b - The value to write.

read

public byte read(int i)

Read this processor's ports.

Specified by:

read in interface Addressable

Parameters:

i - The port number.

Returns:

The value read from the port.

setPortListener

public void setPortListener(int portId,
                            Forwarder listener)

Sets a listener on the passed port.

Parameters:

portId - The port the listener is assigned to.

listener - The listener for the port.

getPorts

public Port[] getPorts()

Get this processors ports.

Specified by:

getPorts in interface Chip

Returns:

An array of ports.

getX

public int getX()

Read the x register. Result is normalised into range [0..255].

Returns:

The contents of the x register.

setX

public void setX(int x)

Sets the x register. Note that this must be called from the thread running the processor. This is not enforced because of performance reasons.

Parameters:

x - The new content for the x register.

getY

public int getY()

Read the y register.

Returns:

The contents of the y register.

setY

public void setY(int y)

Sets the y register. Note that this must be called from the thread running the processor. This is not enforced because of performance reasons.

Parameters:

y - The new value for the y register.

getAccu

public int getAccu()

Read the accu.

Returns:

The current contents of the accumulator register.

setAccu

public void setAccu(int a)

Sets the accu register. Note that this must be called from the thread running the processor. This is not enforced because of performance reasons.

Parameters:

a - The new value for the accumulator.

setPC

public void setPC(int pc)

Set the program counter to a new address.

Parameters:

pc - The new address for the program counter.

getPC

public int getPC()

Read the program counter.

Returns:

the current PC.

IRQ

public void IRQ()

Handles the IRQ interrupt. This method will be the entry point for threads controlling other chips in the simulation, hence needs to be synchronised.

NMI

public void NMI()

Handles the NMI interrupt.

stealCycles

public void stealCycles(int count)

experimental TODO

Parameters:

count -

getStatusRegister

public final byte getStatusRegister()

Get our status flags into a byte value.

Returns:

The contents of the status register.

See Also:

setStatusRegister(byte)

setStatusRegister

public final void setStatusRegister(byte status)

Set our status flags from a byte value.

Parameters:

status - The new value of the status register.

isStatusFlagSet

public boolean isStatusFlagSet(int statusEnum)

Test a single status register flag.

Parameters:

statusEnum - One of the status register constants, e.g. STATUS_FLAG_BREAK.

Returns:

The boolean value of the status flag.

See Also:

STATUS_FLAG_BREAK, STATUS_FLAG_CARRY, STATUS_FLAG_DECIMAL, STATUS_FLAG_INTERRUPT, STATUS_FLAG_NEGATIVE, STATUS_FLAG_OVERFLOW, STATUS_FLAG_ZERO

reset

public void reset()

Initialises the program counter from the reset vector.

Specified by:

reset in interface Chip

toString

public java.lang.String toString()

Returns a string representation of this processor for debug purposes.

Returns:

A string representation of this processor for debug purposes.

setDebugger

public void setDebugger(Debugger d)

Sets a debugger on this processor instance. To switch off debugging set this to null.

Specified by:

setDebugger in interface Processor

Parameters:

d - The debugger to be set.

See Also:

Processor.setDebugger( Debugger )