package org.jscsi.target.scsi.cdb;

 import java.nio.ByteBuffer;

 import org.jscsi.target.util.ReadWrite;

 /**

  * This class represents Command Descriptor Blocks for the <code>WRITE (6)</code> SCSI command.

  * <p>

  * The WRITE (6) command requests that the device server transfer the specified logical block(s) from the data-out

  * buffer and write them.

  * <p>

  * Each logical block transferred includes user data but does not include protection information. Each logical block

  * written includes user data and, if the medium is formatted with protection information enabled, protection

  * information.

  * <p>

  * A TRANSFER LENGTH field set to zero specifies that 256 logical blocks shall be written. Any other value specifies the

  * number of logical blocks that shall be written.

  * 

  * @author Andreas Ergenzinger

  */

 public class Write6Cdb extends WriteCdb {

     public Write6Cdb (ByteBuffer buffer) {

         super(buffer);

     }

     @Override

     protected long deserializeLogicalBlockAddress (ByteBuffer buffer) {

         // the first three bits of byte 1 are reserved, i.e. must be 0,

         // check that

         final byte b = buffer.get(1);

         if (((b >> 5) & 7) != 0) addIllegalFieldPointer(1);

         // read the field's value

         return ((b & 31) << 16) | ReadWrite.readTwoByteInt(buffer, 2);

     }

     @Override

     protected int deserializeTransferLength (ByteBuffer buffer) {

         /*

          * A TRANSFER LENGTH field set to zero specifies that 256 logical blocks shall be written. Any other value

          * specifies the number of logical blocks that shall be written.

          */

         final int value = ReadWrite.readOneByteInt(buffer, 4);

         if (value == 0) return 256;

         return value;

     }

     @Override

     protected int getLogicalBlockAddressFieldIndex () {

         return 1;

     }

     @Override

     protected int getTransferLengthFieldIndex () {

         return 4;

     }

 }