/*
 * $Id$
 *
 * Copyright (C) 2003-2015 JNode.org
 *
 * This library is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation; either version 2.1 of the License, or
 * (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful, but 
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 
 * License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library; If not, write to the Free Software Foundation, Inc., 
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */
 
package org.jnode.driver.serial;

import java.nio.ByteBuffer;
import java.nio.channels.ByteChannel;
import java.security.PrivilegedExceptionAction;
import javax.naming.NameNotFoundException;
import org.jnode.driver.Device;
import org.jnode.driver.Driver;
import org.jnode.driver.DriverException;
import org.jnode.driver.character.ChannelAlreadyOwnedException;
import org.jnode.naming.InitialNaming;
import org.jnode.system.resource.IOResource;
import org.jnode.system.resource.ResourceManager;
import org.jnode.system.resource.ResourceNotFreeException;
import org.jnode.system.resource.ResourceOwner;
import org.jnode.util.AccessControllerUtils;

/**
 * @author mgeisse
 */
public class SerialPortDriver extends Driver implements SerialPortAPI,
    ByteChannel {

    private Device channelOwner;

    private IOResource port;

    private int basePort;

    /**
     * Create new driver instance of this driver
     */
    public SerialPortDriver(int basePort) {
        this.channelOwner = null;
        this.port = null;
        this.basePort = basePort;
    }

    protected void startDevice() throws DriverException {
        try {
            final ResourceManager rm = InitialNaming.lookup(ResourceManager.NAME);
            port = claimPorts(rm, getDevice(), basePort, 8);
            configure(BAUD9600);
            getDevice().registerAPI(SerialPortAPI.class, this);
        } catch (NameNotFoundException nnfex) {
            throw new DriverException(nnfex);
        } catch (ResourceNotFreeException rnfex) {
            throw new DriverException(rnfex);
        }
    }

    protected void stopDevice() {
        port.release();
    }

    public ByteChannel getChannel(Device owner)
        throws ChannelAlreadyOwnedException {
        if (channelOwner != null)
            throw new ChannelAlreadyOwnedException(channelOwner);
        channelOwner = owner;
        return this;
    }

    public boolean isOpen() {
        return true;
    }

    public void close() {
    }

    public void configure(int divisor, int bits, boolean longStop,
                          boolean parity, boolean pEven) {
        if (divisor < 1 || divisor > 65535)
            throw new IllegalArgumentException(
                "invalid baud rate divisor: " + divisor);

        int control;
        switch (bits) {
            case 5:
                control = 0;
                break;
            case 6:
                control = 1;
                break;
            case 7:
                control = 2;
                break;
            case 8:
                control = 3;
                break;
            default:
                throw new IllegalArgumentException("invalid data block bits: "
                    + bits);
        }

        if (longStop) control |= 4;
        if (parity) control |= 8;
        if (pEven) control |= 16;

        flush();
        port.outPortByte(basePort + 3, control | 128);
        port.outPortByte(basePort + 0, divisor);
        port.outPortByte(basePort + 1, divisor >> 8);
        port.outPortByte(basePort + 3, control);
    }

    public void configure(int divisor) {
        configure(divisor, 8, false, false, false);
    }

    public int readSingle() {
        // should detect overruns, maybe parity errors, framing errors, and
        // breaks.

        // FIXME: busy waiting for a bit block to arrive
        while ((port.inPortByte(basePort + 5) & 1) == 0)
            ;
        return port.inPortByte(basePort);
    }

    public void writeSingle(int value) {
        // FIXME: busy waiting for the transmitter buffer to be empty
        while ((port.inPortByte(basePort + 5) & 32) == 0)
            ;
        port.outPortByte(basePort, value);
    }

    /**
     * Wait for all physically cached bit blocks to be sent. This flushes only
     * the hardware buffers, but no waiting data from the input channel.
     */
    private void flushHardware() {
        // FIXME: busy waiting for the holding and shift registers to be empty
        int b;
        do
            b = port.inPortByte(basePort + 5); while ((b & 96) != 96);
    }

    public void flush() {
        // FIXME: currently flushes only the hardware as input buffers are not
        // yet used. This is only relevant to non-blocking I/O.
        flushHardware();
    }

    /**
     * @see java.nio.channels.ByteChannel#read(java.nio.ByteBuffer)
     */
    public int read(ByteBuffer dst) {
        int n = dst.remaining();
        for (int i = 0; i < n; i++)
            dst.put((byte) readSingle());
        return n;
    }

    /**
     * @see java.nio.channels.ByteChannel#write(ByteBuffer)
     */
    public int write(ByteBuffer src) {
        int n = src.remaining();
        for (int i = 0; i < n; i++)
            writeSingle(src.get());
        return n;
    }

    private IOResource claimPorts(final ResourceManager rm,
                                  final ResourceOwner owner, final int low, final int length)
        throws ResourceNotFreeException, DriverException {
        try {
            return AccessControllerUtils
                .doPrivileged(new PrivilegedExceptionAction<IOResource>() {

                    public IOResource run() throws ResourceNotFreeException {
                        return rm.claimIOResource(owner, low, length);
                    }
                });
        } catch (ResourceNotFreeException ex) {
            throw ex;
        } catch (Exception ex) {
            throw new DriverException("Unknown exception", ex);
        }

    }
}