ReadCoilsResponse.java

/***
 * Copyright 2002-2010 jamod development team
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 ***/

package net.wimpi.modbus.msg;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;

import net.wimpi.modbus.Modbus;
import net.wimpi.modbus.util.BitVector;

/**
 * Class implementing a <tt>ReadCoilsResponse</tt>.
 * The implementation directly correlates with the class 1
 * function <i>read coils (FC 1)</i>. It encapsulates
 * the corresponding response message.
 * <p>
 * Coils are understood as bits that can be manipulated
 * (i.e. set or unset).
 *
 * @author Dieter Wimberger
 * @version @version@ (@date@)
 */
public final class ReadCoilsResponse extends ModbusResponse {

    // instance attributes
    private BitVector m_Coils;

    /**
     * Constructs a new <tt>ReadCoilsResponse</tt>
     * instance.
     */
    public ReadCoilsResponse() {
        super();
        setFunctionCode(Modbus.READ_COILS);
    }// constructor(int)

    /**
     * Constructs a new <tt>ReadCoilsResponse</tt>
     * instance with a given count of coils (i.e. bits).
     * <b>
     *
     * @param count the number of bits to be read.
     */
    public ReadCoilsResponse(int count) {
        super();
        m_Coils = new BitVector(count);
        setFunctionCode(Modbus.READ_COILS);
        setDataLength(m_Coils.byteSize() + 1);
    }// constructor(int)

    /**
     * Returns the number of bits (i.e. coils)
     * read with the request.
     * <p>
     *
     * @return the number of bits that have been read.
     */
    public int getBitCount() {
        if (m_Coils == null) {
            return 0;
        } else {
            return m_Coils.size();
        }
    }// getBitCount

    /**
     * Returns the <tt>BitVector</tt> that stores
     * the collection of bits that have been read.
     * <p>
     *
     * @return the <tt>BitVector</tt> holding the
     *         bits that have been read.
     */
    public BitVector getCoils() {
        return m_Coils;
    }// getCoils

    /**
     * Convenience method that returns the state
     * of the bit at the given index.
     * <p>
     *
     * @param index the index of the coil for which
     *            the status should be returned.
     *
     * @return true if set, false otherwise.
     *
     * @throws IndexOutOfBoundsException if the
     *             index is out of bounds
     */
    public boolean getCoilStatus(int index) throws IndexOutOfBoundsException {

        return m_Coils.getBit(index);
    }// getCoilStatus

    /**
     * Sets the status of the given coil.
     *
     * @param index the index of the coil to be set.
     * @param b true if to be set, false for reset.
     */
    public void setCoilStatus(int index, boolean b) {
        m_Coils.setBit(index, b);
    }// setCoilStatus

    @Override
    public void writeData(DataOutput dout) throws IOException {
        dout.writeByte(m_Coils.byteSize());
        dout.write(m_Coils.getBytes(), 0, m_Coils.byteSize());
    }// writeData

    @Override
    public void readData(DataInput din) throws IOException {
        int count = din.readUnsignedByte();
        byte[] data = new byte[count];
        for (int k = 0; k < count; k++) {
            data[k] = din.readByte();
        }
        // decode bytes into bitvector
        m_Coils = BitVector.createBitVector(data);
        // update data length
        setDataLength(count + 1);
    }// readData

}// class ReadCoilsResponse