I'm trying to make a Java program access a parallel port.  Java's comm
API does not provide me with the control I need.  I need to be able to
write to the data and control pins and read the status pins.  Any Java
people know a good solution?  I'm trying to use JNI and create my own
library, but building the library gives me these errors:

ld: warning: cannot find entry symbol _start; defaulting to
0000000008048094
ParallelPort.o: In function `Java_ParallelPort_setAddress':
ParallelPort.cpp:(.text+0x96): undefined reference to `ioperm'
ParallelPort.cpp:(.text+0xaa): undefined reference to `ioperm'

Can anyone help me?  Source follows.

ParallelPort.java
----------
public class ParallelPort {
    static {
        System.loadLibrary("ParallelPort");
    }

    public ParallelPort() {
        setAddress(0x378); // default to lp0
    }

    public ParallelPort(int addr) {
        setAddress(addr);
    }

    public native void setAddress(int addr);

    public native int getAddress();

    public native void sendData(int data);

    public native int readStatus();

    public native void sendControl(int control);
}

==========

ParallelPort.cpp
----------
#include "ParallelPort.h"
#include <jni.h>
#include <stdio.h>

#define extern static
#define REALLY_SLOW_IO
#include <asm/io.h> // port I/O
#undef extern

#include <sys/io.h> // for ioperm

jint DATA;
jint STATUS;
jint CONTROL;

JNIEXPORT void JNICALL Java_ParallelPort_setAddress(JNIEnv *env,
jobject obj,
                           jint addr) {
   DATA = addr;
   STATUS = addr + 1;
   CONTROL = addr +2;

   ioperm(DATA, 3, 1);
   ioperm(0x80, 1, 1);
}

JNIEXPORT jint JNICALL Java_ParallelPort_getAddress(JNIEnv *env,
jobject obj) {
   return DATA;
}

JNIEXPORT void JNICALL Java_ParallelPort_sendData(JNIEnv *env, jobject
obj,
                         jint data) {
   outb(data, DATA);
}

JNIEXPORT jint JNICALL Java_ParallelPort_readStatus(JNIEnv *env,
                           jobject obj) {
   return inb(STATUS);
}

JNIEXPORT void JNICALL Java_ParallelPort_sendControl(JNIEnv *env,
jobject obj,
                            jint control) {
   outb(control, CONTROL);
}

==========

ParallelPort.h (Auto-generated with javah)
----------
/* DO NOT EDIT THIS FILE - it is machine generated */
#include <jni.h>
/* Header for class ParallelPort */

#ifndef _Included_ParallelPort
#define _Included_ParallelPort
#ifdef __cplusplus
extern "C" {
#endif
/*
* Class:     ParallelPort
* Method:    setAddress
* Signature: (I)V
*/
JNIEXPORT void JNICALL Java_ParallelPort_setAddress
 (JNIEnv *, jobject, jint);

/*
* Class:     ParallelPort
* Method:    getAddress
* Signature: ()I
*/
JNIEXPORT jint JNICALL Java_ParallelPort_getAddress
 (JNIEnv *, jobject);

/*
* Class:     ParallelPort
* Method:    sendData
* Signature: (I)V
*/
JNIEXPORT void JNICALL Java_ParallelPort_sendData
 (JNIEnv *, jobject, jint);

/*
* Class:     ParallelPort
* Method:    readStatus
* Signature: ()I
*/
JNIEXPORT jint JNICALL Java_ParallelPort_readStatus
 (JNIEnv *, jobject);

/*
* Class:     ParallelPort
* Method:    sendControl
* Signature: (I)V
*/
JNIEXPORT void JNICALL Java_ParallelPort_sendControl
 (JNIEnv *, jobject, jint);

#ifdef __cplusplus
}
#endif
#endif