Android Open Source - libaums Command Block Wrapper

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License

The source code is released under:

Apache License

Java Source Code

/*
 * (C) Copyright 2014 mjahnen <jahnen@in.tum.de>
 *//from   ww  w.java 2 s .  c  om
 * 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 com.github.mjdev.libaums.driver.scsi.commands;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;

/**
 * This class represents the command block wrapper (CBW) which is always wrapped
 * around a specific SCSI command in the SCSI transparent command set standard.
 * <p>
 * Every SCSI command shall extend this class, call the constructor
 * {@link #CommandBlockWrapper(int, Direction, byte, byte)} with the desired
 * information. When transmitting the command, the
 * {@link #serialize(ByteBuffer)} method has to be called!
 * 
 * @author mjahnen
 * 
 */
public abstract class CommandBlockWrapper {

  /**
   * The direction of the data phase of the SCSI command.
   * 
   * @author mjahnen
   * 
   */
  public enum Direction {
    /**
     * Means from device to host (Android).
     */
    IN,
    /**
     * Means from host (Android) to device.
     */
    OUT,
    /**
     * There is no data phase
     */
    NONE
  }

  private static final int D_CBW_SIGNATURE = 0x43425355;

  private int dCbwTag;
  private int dCbwDataTransferLength;
  private byte bmCbwFlags;
  private byte bCbwLun;
  private byte bCbwcbLength;
  private Direction direction;

  /**
   * Constructs a new command block wrapper with the given information which
   * can than easily be serialized with {@link #serialize(ByteBuffer)}.
   * 
   * @param transferLength
   *            The bytes which should be transferred in the following data
   *            phase (Zero if no data phase).
   * @param direction
   *            The direction the data shall be transferred in the data phase.
   *            If there is no data phase it should be
   *            {@link com.github.mjdev.libaums.driver.scsi.commands.CommandBlockWrapper.Direction #NONE
   *            NONE}
   * @param lun
   *            The logical unit number the command is directed to.
   * @param cbwcbLength
   *            The length in bytes of the scsi command.
   */
  protected CommandBlockWrapper(int transferLength, Direction direction, byte lun,
      byte cbwcbLength) {
    dCbwDataTransferLength = transferLength;
    this.direction = direction;
    if (direction == Direction.IN)
      bmCbwFlags = (byte) 0x80;
    bCbwLun = lun;
    bCbwcbLength = cbwcbLength;
  }

  /**
   * Serializes the command block wrapper for transmission.
   * <p>
   * This method should be called in every subclass right before the specific
   * SCSI command serializes itself to the buffer!
   * 
   * @param buffer
   *            The buffer were the serialized data should be copied to.
   */
  public void serialize(ByteBuffer buffer) {
    buffer.order(ByteOrder.LITTLE_ENDIAN);
    buffer.putInt(D_CBW_SIGNATURE);
    buffer.putInt(dCbwTag);
    buffer.putInt(dCbwDataTransferLength);
    buffer.put(bmCbwFlags);
    buffer.put(bCbwLun);
    buffer.put(bCbwcbLength);
  }

  /**
   * Returns the tag which can be used to determine the corresponding
   * {@link com.github.mjdev.libaums.driver.scsi.commands.CommandStatusWrapper
   * CBW}.
   * 
   * @return The command block wrapper tag.
   * @see com.github.mjdev.libaums.driver.scsi.commands.CommandStatusWrapper
   *      #getdCswTag()
   */
  public int getdCbwTag() {
    return dCbwTag;
  }

  /**
   * Sets the tag which can be used to determine the corresponding
   * {@link com.github.mjdev.libaums.driver.scsi.commands.CommandStatusWrapper
   * CBW}.
   * 
   * @return The command block wrapper tag
   * @see com.github.mjdev.libaums.driver.scsi.commands.CommandStatusWrapper
   *      #getdCswTag()
   */
  public void setdCbwTag(int dCbwTag) {
    this.dCbwTag = dCbwTag;
  }

  /**
   * Returns the amount of bytes which should be transmitted in the data
   * phase.
   * 
   * @return The length in bytes.
   */
  public int getdCbwDataTransferLength() {
    return dCbwDataTransferLength;
  }

  /**
   * Returns the direction in the data phase.
   * 
   * @return The direction.
   * @see com.github.mjdev.libaums.driver.scsi.commands.CommandBlockWrapper.Direction
   *      Direction
   */
  public Direction getDirection() {
    return direction;
  }

}

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