rtl8139rxring.java

来自「纯java操作系统jnode,安装简单和操作简单的个人使用的Java操作系统」· Java 代码 · 共 150 行

/*
 * $Id: RTL8139RxRing.java,v 1.1 2003/11/25 11:52:24 epr Exp $
 */

package org.jnode.driver.net.rtl8139;

import org.jnode.net.SocketBuffer;
import org.jnode.system.MemoryResource;
import org.jnode.system.ResourceManager;
import org.jnode.vm.Address;

/**
 * @author Martin Husted Hartvig
 */

public class RTL8139RxRing implements RTL8139Constants
{

  private static final int UPD_SIZE = 16;
  //private static final int FRAME_SIZE = MAX_ETH_FRAME_LEN;

  /** The #frames in this ring */
  private final int nrFrames;

  /** The actual data */
  private final byte[] data;

  /** MemoryResource mapper around data */
  private final MemoryResource mem;

  /** Offset within mem of first UDP */
  private final int firstUPDOffset;

  /** 32-bit address first UDP */
  private final Address firstUPDAddress;

  private int index;


  /**
   * Create a new instance
   * 
   * @param nrFrames The number of complete ethernet frames in this ring.
   * @param rm       
   */

  public RTL8139RxRing(int nrFrames, ResourceManager rm)
  {

    // Create a large enough buffer
    final int size = TOTAL_RX_BUF_SIZE;//(nrFrames * (UPD_SIZE + FRAME_SIZE)) + 16/*alignment*/;
    this.data = new byte[size];
    this.nrFrames = nrFrames;
    this.mem = rm.asMemoryResource(data);

    final Address memAddr = mem.getAddress();
    int offset = 0;

    this.firstUPDOffset = offset;
    this.firstUPDAddress = Address.add(memAddr, firstUPDOffset);
  }

  /**
   * Initialize this ring to its default (empty) state
   */

  public void initialize()
  {
    index = 0;
  }

  /**
   * Gets the packet status of the UPD at the given index
   */
  public int getPktStatus()
  {
    final int updOffset = firstUPDOffset + index;

    return mem.getInt(updOffset);
  }


  /**
   * Sets the packet status of the UPD at the given index
   * 
   * @param index 
   * @param value The new pkt status value
   */
  public void setPktStatus(int index, int value)
  {
    final int updOffset = firstUPDOffset + (index * UPD_SIZE) - 4;

    mem.setInt(updOffset + 4, value);

    this.index = index;
  }


  public void setIndex(int index)
  {
    this.index = index;
  }


  public int getIndex()
  {
    return index;
  }


  /**
   * Gets the packet data of UPD with the current index into a SocketBuffer
   */

  public SocketBuffer getPacket(int _length)
  {

    final int updOffset = firstUPDOffset + index;
    final SocketBuffer skbuf = new SocketBuffer();

    if (_length > 0)
    {
      skbuf.append(data, updOffset + 4, _length - 4);
    }

    index = (index + _length + 4 + 3) & ~3;
    index &= (RX_BUF_SIZE - 1);

    return skbuf;
  }

  /**
   * Gets the address of the first UPD of this ring.
   */

  public Address getFirstUPDAddress()
  {
    return firstUPDAddress;
  }

  /**
   * Gets the number of frames of this ring
   */

  public int getNrFrames()
  {
    return nrFrames;
  }
}