✎ javacard-api-samples:utility [wiki]

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====== Utility Sample Code ======

[[https://javacardos.com/javacardforum/download/file.php?id=519|Download Sample Code]]                   [[https://javacardos.com/javacardforum/viewtopic.php?f=31&t=716|Discussion]]
<code java>
/*
 * @file  Utility.java
 * @brief The Class of Util Sample Code in JavaCard API Specification
 * @comment The purpose of this example is only used to show the usage of API functions and there is no practical significance.
 * @copyright Copyright(C) 2016 JavaCardOS Technologies Co., Ltd. All rights reserved.
 */
package JavaCardOS.Sample.Utility;
 
import javacard.framework.*;
 
public class Utility extends Applet
{
    public static final byte INS_ARRAY_COPY_APDU    = 0x01;
    public static final byte INS_ARRAY_COMPARE_APDU  = 0x02;
    public static final byte INS_SHORT_VALUE_APDU   = 0x03;
    //Redefine the SW1,SW2 error codes
    short SW_DATA_CONVERT_ERROR = 0x6F80;
     
    public static void install(byte[] bArray, short bOffset, byte bLength) 
    {
        new Utility().register(bArray, (short) (bOffset + 1), bArray[bOffset]);
    }
 
    public void process(APDU apdu)
    {
        if (selectingApplet())
        {
            return;
        }
        //Get the apdu buffer datas 
        byte[] buf = apdu.getBuffer();
        byte ins = buf[ISO7816.OFFSET_INS];
         
        switch (ins)
        {
        case (byte)INS_ARRAY_COPY_APDU:
            apdu.setIncomingAndReceive();
            //Create a transient byte array with the specified array length
            byte[] tmpMemory = JCSystem.makeTransientByteArray((short)10, JCSystem.CLEAR_ON_DESELECT);
            //Fill the byte array 'tmpMemory' (non-atomically) with the value 0x66, beginning from the 0 position, the filling length is 10.
            Util.arrayFillNonAtomic(tmpMemory, (short)0, (short)10, (byte)0x66);
            //Copy an array from the 'tmpMemory' array to APDU Buffer.
            Util.arrayCopy(tmpMemory, (short)0, buf, (short)0, (short)10);
            //Send the length of 10 bytes from the APDU buffer
            apdu.setOutgoingAndSend((short)0, (short)10);
            break;
             
        case INS_ARRAY_COMPARE_APDU:
            //Calling this method indicates that this APDU has incoming data. 
            apdu.setIncomingAndReceive();
         
            //Get the incoming data length(Lc).
            short lc = apdu.getIncomingLength();
             
            if (lc != 0x04)
            {
                ISOException.throwIt(ISO7816.SW_WRONG_LENGTH);
            }
            //Define a byte array named 'cmpArray'
            byte[] cmpArray = {(byte) 0x01, (byte) 0x02, (byte) 0x03, (byte) 0x04};
            //Compare an array from the specified source array,
            byte cmpResult = Util.arrayCompare(cmpArray, (short)0, buf, (short)ISO7816.OFFSET_CDATA, (short)4);
            //if the comparison of the results is same, set the value of 'buf' byte array to "01", if not, set to "02"
            if (cmpResult == (byte)0)
            {
                buf[0] = (byte)1;
            }
            else
            {
                buf[0] = (byte)2;
            }
            apdu.setOutgoingAndSend((short)0, (short)1);
            break;
             
        case INS_SHORT_VALUE_APDU:
            apdu.setIncomingAndReceive();
            //Get the incoming data length(Lc).
            short len = apdu.getIncomingLength();
             
            if (len != 0x02)
            {
                ISOException.throwIt(ISO7816.SW_WRONG_LENGTH);
            }
            //Concatenates the two parameter bytes to form a short value.
            short short_value1 = Util.makeShort(buf[ISO7816.OFFSET_CDATA], buf[ISO7816.OFFSET_CDATA+1]);
             
            //Concatenates two bytes in a byte array to form a short value.
            short short_value2 = Util.getShort(buf, ISO7816.OFFSET_CDATA);
            //compare the result value that two methods converted
            if (short_value1 != short_value2)
            {
                ISOException.throwIt(SW_DATA_CONVERT_ERROR);
            }
             
            //Deposits the short value as two successive bytes at the specified offset in the byte array.
            Util.setShort(buf, (short)0, short_value1);
            apdu.setOutgoingAndSend((short)0, (short)2);
            break;
        default:
            ISOException.throwIt(ISO7816.SW_INS_NOT_SUPPORTED);
        }
    }
}
</code>
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