Intel8255 Class Reference

Intel 8255 base emulation class. More...

#include <8255.h>

Inheritance diagram for Intel8255:

List of all members.

Public Types
enum	{ PortA = 0, PortB = 1, PortC = 2 }
Public Member Functions
	Intel8255 ()
	Constructor.
virtual	~Intel8255 ()
	Destructor.
void	reset (void)
	Reset state (as if activating reset signal)
void	ackPortA (void)
	External acknowledgement of port A.
void	ackPortB (void)
	External acknowledgement of port B.
virtual void	strobePortA (void)
	Strobed Input (latch to port A)
virtual void	strobePortB (void)
	Strobed Input (latch to port B)
uint8_t	readPortA (void)
	Called when CPU reads port A.
uint8_t	readPortB (void)
	Called when CPU reads port B.
uint8_t	readPortC (void)
	Called when CPU reads port C.
uint8_t	readControl (void)
	Called when CPU reads control port.
uint8_t	readByPort (const uint8_t p03)
	Called when CPU reads from the chip.
void	writePortA (const uint8_t data, uint8_t mask=0xFFU)
	Called when CPU writes port A.
void	writePortB (const uint8_t data, uint8_t mask=0xFFU)
	Called when CPU writes port B.
void	writePortC (const uint8_t data, uint8_t mask=0xFFU)
	Called when CPU writes port C.
void	writeControl (const uint8_t data)
	Called when CPU writes control port.
void	writeByPort (const uint8_t p03, const uint8_t data)
	Called when CPU writes to the chip.
virtual uint8_t	inPortA (void) const
	Called by 8255 emulation to latch from port A pins.
virtual uint8_t	inPortB (void) const
	Called by 8255 emulation to latch from port B pins.
virtual uint8_t	inPortC (void) const
	Called by 8255 emulation to latch from port C pins.
virtual void	outPortA (const uint8_t mask)
	Called by 8255 emulation when latching to port A pins.
virtual void	outPortB (const uint8_t mask)
	Called by 8255 emulation when latching to port B pins.
virtual void	outPortC (const uint8_t mask)
	Called by 8255 emulation when latching to port C pins.
void	updateINTR_A (void)
	Internal 8255 emulation code to update INTR A signal.
void	updateINTR_B (void)
	Internal 8255 emulation code to update INTR B signal.
void	checkINTR_A (void)
	Internal 8255 emulation code to check INTR A change and dispatch signal.
void	checkINTR_B (void)
	Internal 8255 emulation code to check INTR B change and dispatch signal.
virtual void	sigINTR_A (void)
	Called by 8255 emulation when INTR A signal changes to dispatch signal.
virtual void	sigINTR_B (void)
	Called by 8255 emulation when INTR B signal changes to dispatch signal.
const char *	getName (void) const
	Retrieve the name of this chip (for debug/UI purposes)
const char *	pinName (const unsigned int port, const unsigned int i) const
	Retrieve the name of a pin on the chip related to port A, B, or C (what it's connected to) (for debug/UI purposes)
const char *	portName (const unsigned int port) const
	Retrieve the name of a port (A, B, or C) (for debug/UI purposes)
Public Attributes
uint8_t	portAWriteMask = 0
	Port A write mask. Controls which bits are writeable.
uint8_t	portBWriteMask = 0
	Port B write mask. Controls which bits are writeable.
uint8_t	portCWriteMask = 0
	Port C write mask. Controls which bits are writeable.
const char *	ppiName
	PPI chip name (for debug/UI purposes)
const char *	pinNames [3][8] = {}
	Pin names (for debug/UI purposes)
const char *	portNames [3] = {}
	Port names (for debug/UI purposes)
uint8_t	latchOutPortA = 0
	Port A output latch.
uint8_t	latchOutPortB = 0
	Port B output latch.
uint8_t	latchOutPortC = 0
	Port C output latch.
uint8_t	mode = 0
	PPI mode byte.
bool	IBF_A = false
	Input Buffer Full, port A contains information (port A, Mode 1)
bool	IBF_B = false
	Input Buffer Full, port B contains information (port B, Mode 1)
bool	OBF_A = false
	Output Buffer Full, port A contains information for the external device (port A, Mode 1)
bool	OBF_B = false
	Output Buffer Full, port B contains information for the external device (port B, Mode 1)
bool	INTR_A = false
	Interrupt Request A (to the microprocessor)
bool	INTR_B = false
	Interrupt Request B (to the microprocessor)
bool	pINTR_A = false
	Previous Interrupt Request A state (for change detection)
bool	pINTR_B = false
	Previous Interrupt Request B state (for change detection)
bool	INTE_1 = false
	Interrupt 1 enable (mode 2)
bool	INTE_2 = false
	Interrupt 2 enable (mode 2)
bool	INTE_A = false
	Interrupt A enable.
bool	INTE_B = false
	Interrupt B enable.
Static Protected Member Functions
static const char *	nil_if_null (const char *str)
	Return string "str", or "" (empty string) if str == NULL.

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Detailed Description

Intel 8255 base emulation class.

Intel 8255 Programmable Peripheral Interface emulation class. The base class handles the functions and register I/O to emulate the 8255, while the subclass implements behavior of hardware attached to the 8255.

All emulation is written to follow Intel's datasheet as closely as possible.

Intel 8255A datasheet

NOTE: Mode 2 emulation has NOT been tested yet!

Definition at line 18 of file 8255.h.

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Member Enumeration Documentation

anonymous enum

Port enumeration (A, B, and C)

Enumerator:

PortA	Port A (input or output)
PortB	Port B (input or output)
PortC	Port C (input, output, or half input half output)

Definition at line 23 of file 8255.h.

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The documentation for this class was generated from the following files:

• include/8255.h
• src/hardware/8255.cpp