ReadMultipleRegistersResponse.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.ModbusCoupler;
import net.wimpi.modbus.procimg.ProcessImageFactory;
import net.wimpi.modbus.procimg.Register;

/**
 * Class implementing a <tt>ReadMultipleRegistersResponse</tt>.
 * The implementation directly correlates with the class 0
 * function <i>read multiple registers (FC 3)</i>. It encapsulates
 * the corresponding response message.
 *
 * @author Dieter Wimberger
 * @version @version@ (@date@)
 */
public final class ReadMultipleRegistersResponse extends ModbusResponse {

    // instance attributes
    private int m_ByteCount;
    private Register[] m_Registers;

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

    /**
     * Constructs a new <tt>ReadInputRegistersResponse</tt>
     * instance.
     *
     * @param registers the Register[] holding response registers.
     */
    public ReadMultipleRegistersResponse(Register[] registers) {
        super();
        m_Registers = registers;
        m_ByteCount = registers.length * 2;
        setFunctionCode(Modbus.READ_MULTIPLE_REGISTERS);
        // set correct data length excluding unit id and fc
        setDataLength(m_ByteCount + 1);
    }// constructor

    /**
     * Returns the number of bytes that have been read.
     * <p>
     *
     * @return the number of bytes that have been read
     *         as <tt>int</tt>.
     */
    public int getByteCount() {
        return m_ByteCount;
    }// getByteCount

    /**
     * Returns the number of words that have been read.
     * The returned value should be half of the
     * the byte count of this
     * <tt>ReadMultipleRegistersResponse</tt>.
     * <p>
     *
     * @return the number of words that have been read
     *         as <tt>int</tt>.
     */
    public int getWordCount() {
        return m_ByteCount / 2;
    }// getWordCount

    /**
     * Sets the number of bytes that have been returned.
     * <p>
     *
     * @param count the number of bytes as <tt>int</tt>.
     */
    private void setByteCount(int count) {
        m_ByteCount = count;
    }// setByteCount

    /**
     * Returns the value of the register at
     * the given position (relative to the reference
     * used in the request) interpreted as unsigned short.
     * <p>
     *
     * @param index the relative index of the register
     *            for which the value should be retrieved.
     *
     * @return the value as <tt>int</tt>.
     *
     * @throws IndexOutOfBoundsException if
     *             the index is out of bounds.
     */
    public int getRegisterValue(int index) throws IndexOutOfBoundsException {
        return m_Registers[index].toUnsignedShort();
    }// getRegisterValue

    /**
     * Returns the <tt>Register</tt> at
     * the given position (relative to the reference
     * used in the request).
     * <p>
     *
     * @param index the relative index of the <tt>Register</tt>.
     *
     * @return the register as <tt>Register</tt>.
     *
     * @throws IndexOutOfBoundsException if
     *             the index is out of bounds.
     */
    public Register getRegister(int index) throws IndexOutOfBoundsException {

        if (index >= getWordCount()) {
            throw new IndexOutOfBoundsException();
        } else {
            return m_Registers[index];
        }
    }// getRegister

    /**
     * Returns a reference to the array of registers
     * read.
     *
     * @return a <tt>Register[]</tt> instance.
     */
    public Register[] getRegisters() {
        return m_Registers;
    }// getRegisters

    @Override
    public void writeData(DataOutput dout) throws IOException {
        dout.writeByte(m_ByteCount);
        for (int k = 0; k < getWordCount(); k++) {
            dout.write(m_Registers[k].toBytes());
        }
    }// writeData

    @Override
    public void readData(DataInput din) throws IOException {
        setByteCount(din.readUnsignedByte());

        m_Registers = new Register[getWordCount()];
        ProcessImageFactory pimf = ModbusCoupler.getReference().getProcessImageFactory();

        for (int k = 0; k < getWordCount(); k++) {
            m_Registers[k] = pimf.createRegister(din.readByte(), din.readByte());
        }

        // update data length
        setDataLength(getByteCount() + 1);
    }// readData

}// class ReadMultipleRegistersResponse