Sergio:
I presume your main question is -to process APDUs as your read
or not, when the incoming APDUs can be larger than 37 bytes(5+32).
Ideally, you would prefer to process APDU as you read. The Java Card
API documentation denotes this;
// process bytes in buffer[5] to buffer[readCount+4]
In other words you would;
Util.arrayCopyNonAtomic(apduBuffer, ISO7816.OFFSET_CDATA, apduBuffer,
(byte)0, bytesRead);
If you have not already read the chapter 8 of the book "JavaCard
Technology for Smart Cards" by Zhiqun Chen, please do so. Also
check the HelloWorld.java example in Sun's Java Card Development
Kit.
Hope this helps.
-Mayank
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> Date: Fri, 30 Mar 2001 10:18:07 -0500 (EST)
> From: Sergio Lopez <[EMAIL PROTECTED]>
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> Subject: [OCF] how to use it correctly?
> Resent-Date: Fri, 30 Mar 2001 17:18:27 +0200 (CEST)
>
> Dear Gurus,
>
> I am a newcomer in the Java Card World.
>
> I have written only a few test applets to run on the card, similar to the
> examples provided by the Sun Microsystems.
>
> Moving forward, I have found, that in the Java Card 2.1.1 Application
> Programming Interface they recommend to use slightly different technique to
> send and receive APDU, than in the examples.
>
> How would you explain the following part of the javacard.framework.APDU
> class documentation:
>
> "The incoming APDU data size may be bigger than the APDU buffer size and may
> therefore need to be read in portions by the applet."
>
> What is the correct way of APDU buffer usage:
>
> First variant:
>
> /***** Step1: receive all incoming APDU data *****/
>
> short readCount = apdu.setIncomingAndReceive();
>
> short bytesLeft = (short) (buffer[ISO7816.OFFSET_LC] & 0x00FF);
>
> while ( bytesLeft > 0){
>
> bytesLeft -= readCount;
>
> readCount = apdu.receiveBytes ( ISO7816.OFFSET_CDATA );
>
> /***** Step2: acces any part of the TOTAL resulting APDU buffer to process
> data ***** /
>
> processAllBuffer();
>
> }
>
>
> Second variant:
>
> /***** Step1: receive the portion of the incoming APDU data (of the
> readCount length) *****/
>
> short readCount = apdu.setIncomingAndReceive();
>
> short bytesLeft = (short) (buffer[ISO7816.OFFSET_LC] & 0x00FF);
>
> while ( bytesLeft > 0){
>
> /***** Step2: access only this particular portion of the APDU data to
> process *****/
>
> processPortionOfBuffer();
>
> bytesLeft -= readCount;
>
> readCount = apdu.receiveBytes ( ISO7816.OFFSET_CDATA );
>
> }
>
> Thanks!
>
> With every good wish to all of you,
> Sergio.
>
>
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