ch.aplu.util
Class LptPort

java.lang.Object
  ch.aplu.util.LptPort

public class LptPort
extends java.lang.Object

Support to write to and read from the LPT port registers on a Windows operating system. Uses the Java Native Interface (JNI) and INPOUT32.DLL by Jan Axelsons. Circumvents Windows protection of I/O-ports on W2K, XP, W2003 OS by installing a driver on the fly (when opening the port). INPOUT32.DLL and JLPTPORT.DLL needed in file system path (distributed with Examples, Chap. 34).

Field Summary

static int	ACKNOWLEDGE Bit value of Acknowledge line in status register of LPT port (at base address + 1).
static int	AUTOLINEFEED Bit value of Auto Linefeed line in control register of LPT port (at base address + 2).
static int	BUSY Bit value of Busy line in status register of LPT port (at base address + 1).
static int	DATA0 Bit value of bit 0 in data register of LPT port (at base address).
static int	DATA1 Bit value of bit 1 in data register of LPT port (at base address).
static int	DATA2 Bit value of bit 2 in data register of LPT port (at base address).
static int	DATA3 Bit value of bit 3 in data register of LPT port (at base address).
static int	DATA4 Bit value of bit 4 in data register of LPT port (at base address).
static int	DATA5 Bit value of bit 5 in data register of LPT port (at base address).
static int	DATA6 Bit value of bit 6 in data register of LPT port (at base address).
static int	DATA7 Bit value of bit 7 in data register of LPT port (at base address).
static int	ERROR Bit value of Error line in status register of LPT port (at base address + 1).
static int	INITRESET Bit value of Init/Reset line in control register of LPT port (at base address + 2).
static int	PAPEREND Bit value of Paper End line in status register of LPT port (at base address + 1).
static int	SELECT Bit value of Select line in status register of LPT port (at base address + 1).
static int	SELECTIN Bit value of Select In line in control register of LPT port (at base address + 2).
static int	STROBE Bit value of Strobe line in control register of LPT port (at base address + 2).

Constructor Summary

LptPort()

Method Summary

void	close() Close port Do nothing, if port is not open.
boolean	isOpen() Return true if port is open, false otherwise.
int	open(int address) Open LPT port at specified base address, e.g. 0x378.
int	readData() Return content of data port (at base address) in lower byte.
int	readStatus() Return content of status port (at base address + 1) in lower byte.
int	writeControl(int data) Write lower byte of data into control port (at base address + 2).
int	writeData(int data) Write lower byte of data into data port (at base address).

Methods inherited from class java.lang.Object

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

Field Detail

DATA0

public static final int DATA0

Bit value of bit 0 in data register of LPT port (at base address). Data may be written (to the external device) or read (from the external device).

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Constant Field Values

DATA1

public static final int DATA1

Bit value of bit 1 in data register of LPT port (at base address). Data may be written (to the external device) or read (from the external device).

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Constant Field Values

DATA2

public static final int DATA2

Bit value of bit 2 in data register of LPT port (at base address). Data may be written (to the external device) or read (from the external device).

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Constant Field Values

DATA3

public static final int DATA3

Bit value of bit 3 in data register of LPT port (at base address). Data may be written (to the external device) or read (from the external device).

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Constant Field Values

DATA4

public static final int DATA4

Bit value of bit 4 in data register of LPT port (at base address). Data may be written (to the external device) or read (from the external device).

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Constant Field Values

DATA5

public static final int DATA5

Bit value of bit 5 in data register of LPT port (at base address). Data may be written (to the external device) or read (from the external device).

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Constant Field Values

DATA6

public static final int DATA6

Bit value of bit 6 in data register of LPT port (at base address). Data may be written (to the external device) or read (from the external device).

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Constant Field Values

DATA7

public static final int DATA7

Bit value of bit 7 in data register of LPT port (at base address). Data may be written (to the external device) or read (from the external device).

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Constant Field Values

ERROR

public static final int ERROR

Bit value of Error line in status register of LPT port (at base address + 1). The external device informs the program about special conditions.

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Constant Field Values

SELECT

public static final int SELECT

Bit value of Select line in status register of LPT port (at base address + 1). The external device informs the program about special conditions.

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Constant Field Values

PAPEREND

public static final int PAPEREND

Bit value of Paper End line in status register of LPT port (at base address + 1). The external device informs the program about special conditions.

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Constant Field Values

ACKNOWLEDGE

public static final int ACKNOWLEDGE

Bit value of Acknowledge line in status register of LPT port (at base address + 1). The external device informs the program about special conditions.

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Constant Field Values

BUSY

public static final int BUSY

Bit value of Busy line in status register of LPT port (at base address + 1). The external device informs the program about special conditions.

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Constant Field Values

STROBE

public static final int STROBE

Bit value of Strobe line in control register of LPT port (at base address + 2). The program sends some special commands to the external device.

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Constant Field Values

AUTOLINEFEED

public static final int AUTOLINEFEED

Bit value of Auto Linefeed line in control register of LPT port (at base address + 2). The program sends some special commands to the external device.

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Constant Field Values

INITRESET

public static final int INITRESET

Bit value of Init/Reset line in control register of LPT port (at base address + 2). The program sends some special commands to the external device.

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Constant Field Values

SELECTIN

public static final int SELECTIN

Bit value of Select In line in control register of LPT port (at base address + 2). The program sends some special commands to the external device.

See Also:

Constant Field Values

Constructor Detail

LptPort

public LptPort()

Method Detail

open

public int open(int address)

Open LPT port at specified base address, e.g. 0x378. Return 0 if successful, -1 otherwise.

isOpen

public boolean isOpen()

Return true if port is open, false otherwise.

writeData

public int writeData(int data)

Write lower byte of data into data port (at base address). Upper byte is ignored. Return -1 if port is not open, 0 otherwise

writeControl

public int writeControl(int data)

Write lower byte of data into control port (at base address + 2). Upper byte is ignored. Return -1 if port is not open, 0 otherwise

readData

public int readData()

Return content of data port (at base address) in lower byte. Upper byte is 0. Return -1 if port is not open.

readStatus

public int readStatus()

Return content of status port (at base address + 1) in lower byte. Upper byte is 0. Return -1 if port is not open.

close

public void close()

Close port Do nothing, if port is not open.