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JCA is an EPICS Channel Access library for Java. For more information concerning EPICS or Channel Access please refer to the <a href="http://www.aps.anl.gov/epics">EPICS Web pages</a> or read the <a href="http://www.aps.anl.gov/epics/base/R3-14/8-docs/CAref.html">Channel Access manual (3.14)</a>. <p>This module also includes CAJ, A 100% pure Java implementation of the EPICS Channel Access library.</p>

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/*
 * Copyright (c) 2004 by Cosylab
 *
 * The full license specifying the redistribution, modification, usage and other
 * rights and obligations is included with the distribution of this project in
 * the file "LICENSE-CAJ". If the license is not included visit Cosylab web site,
 * .
 *
 * THIS SOFTWARE IS PROVIDED AS-IS WITHOUT WARRANTY OF ANY KIND, NOT EVEN THE
 * IMPLIED WARRANTY OF MERCHANTABILITY. THE AUTHOR OF THIS SOFTWARE, ASSUMES
 * _NO_ RESPONSIBILITY FOR ANY CONSEQUENCE RESULTING FROM THE USE, MODIFICATION,
 * OR REDISTRIBUTION OF THIS SOFTWARE.
 */

package com.cosylab.epics.caj.cas.util;

import gov.aps.jca.CAException;
import gov.aps.jca.CAStatus;
import gov.aps.jca.cas.ProcessVariable;
import gov.aps.jca.cas.ProcessVariableEventCallback;
import gov.aps.jca.cas.ProcessVariableReadCallback;
import gov.aps.jca.cas.ProcessVariableWriteCallback;
import gov.aps.jca.dbr.DBR;
import gov.aps.jca.dbr.DBRType;
import gov.aps.jca.dbr.DBR_Enum;
import gov.aps.jca.dbr.DBR_TIME_LABELS_Enum;

/**
 * Abstract convenient enumeration process variable implementation.
 */
public abstract class EnumProcessVariable extends ProcessVariable {
    /**
     * Enum PV constructor.
     * 
     * @param name
     *            process variable name.
     * @param eventCallback
     *            event callback, can be null.
     */
    public EnumProcessVariable(String name, ProcessVariableEventCallback eventCallback) {
        super(name, eventCallback);
    }

    /**
     * Return DBRType.ENUM type as native type.
     * 
     * @see gov.aps.jca.cas.ProcessVariable#getType()
     */
    public DBRType getType() {
        return DBRType.ENUM;
    }

    /**
     * Casts DBR to DBR_TIME_LABELS_Enum, sets labels
     * returned by getEnumLabels() and delegates operation of
     * reading a value to readValue method.
     * 
     * @see gov.aps.jca.cas.ProcessVariable#read(gov.aps.jca.dbr.DBR,
     *      gov.aps.jca.cas.ProcessVariableReadCallback)
     */
    public CAStatus read(DBR value, ProcessVariableReadCallback asyncReadCallback) throws CAException {

        // for ENUM type input DBR is always DBR_TIME_LABELS_Enum
        DBR_TIME_LABELS_Enum enumValue = (DBR_TIME_LABELS_Enum) value;

        // set labels
        enumValue.setLabels(getEnumLabels());

        // read value
        return readValue(enumValue, asyncReadCallback);
    }

    /**
     * Read value. Reference implementation:
     * 
     *      * 	{
     * 
     * 		// for async. completion, return null,
     * 		// set value (and status) to enumValue and
     * 		// report completion using asyncReadCallback callback.
     * 		// return null;
     * 	
     * 		// BEGIN optional (to override defaults) 
     *
     *      {@code
     * 		// set status and severity
     * 		enumValue.setStatus(Status.\);
     * 		enumValue.setSeverity(Severity.\);
     * 		
     * 		// set timestamp
     * 		enumValue.setTimestamp(timestamp);
     * 		
     * 		// END optional (to override defaults)
     * 		
     * 		// set value to given DBR (example of copying value)
     * 		// given DBR has already allocated an array of elements client has requested
     * 		// it contains maximum number of elements to fill
     * 		short[] arrayValue = value.getEnumValue();
     * 		int elementCount = Math.min(\.length, arrayValue.length);
     * 		System.arraycopy(\, 0, arrayValue, 0, elementCount);
     * 
     * 		// return read completion status
     * 		return CAStatus.NORMAL;
     *      }
     * 	}
     * 
     * 
     * 
     * @see gov.aps.jca.cas.ProcessVariable#read(gov.aps.jca.dbr.DBR,
     *      gov.aps.jca.cas.ProcessVariableReadCallback)
     */
    protected abstract CAStatus readValue(DBR_TIME_LABELS_Enum value, ProcessVariableReadCallback asyncReadCallback)
            throws CAException;

    /**
     * Casts DBR to DBR_Enum and delegates operation
     * of writing a value to writeValue method.
     * 
     * @see gov.aps.jca.cas.ProcessVariable#write(gov.aps.jca.dbr.DBR,
     *      gov.aps.jca.cas.ProcessVariableWriteCallback)
     */
    public CAStatus write(DBR value, ProcessVariableWriteCallback asyncWriteCallback) throws CAException {

        // for ENUM type input DBR is always DBR_Enum
        DBR_Enum enumValue = (DBR_Enum) value;

        return writeValue(enumValue, asyncWriteCallback);
    }

    /**
     * Write value. Reference implementation:
     * 
     *      * {
     * 
     *     // for async. completion, return null,
     *     // set value (and status) from enumValue,
     *     // notify if there is an interest and
     *     // report completion using asyncWriteCallback callback.
     *     // return null;
     * 
     *     {@code
     *     // set value from given DBR here (scalar example)
     *     this.value = value.getEnumValue()[0];
     * 
     *     // notify, set appropirate Monitor mask (VALUE, LOG, ALARM)
     *     if (status == CAStatus.NORMAL && interest) {
     *         DBR monitorDBR = AbstractCASResponseHandler.createDBRforReading(this);
     *         ((DBR_Enum) monitorDBR).getEnumValue()[0] = this.value;
     *
     *         // set labels
     *         ((LABELS) monitorDBR).setLabels(getEnumLabels());
     *
     *         // set status, severity and time here (see readValue method
     *         // example)
     *         fillInStatusAndTime((TIME) monitorDBR);
     * 
     *         eventCallback.postEvent(Monitor.VALUE | Monitor.LOG, value);
     *     }
     * 
     *     // return read completion status
     *     return CAStatus.NORMAL;
     *     }
     * }
     * 
     * 
     * @see gov.aps.jca.cas.ProcessVariable#write(gov.aps.jca.dbr.DBR,
     *      gov.aps.jca.cas.ProcessVariableWriteCallback)
     */
    protected abstract CAStatus writeValue(DBR_Enum value, ProcessVariableWriteCallback asyncWriteCallback)
            throws CAException;

}