Class DirectByteBuffer

classpath/java/nio/DirectByteBuffer.java:15–105

import sun.misc.Unsafe;

class DirectByteBuffer extends ByteBuffer {
  private static final Unsafe unsafe = Unsafe.getUnsafe();
  private static final int baseOffset = unsafe.arrayBaseOffset(byte[].class);

  protected final long address;

  protected DirectByteBuffer(long address, int capacity, boolean readOnly) {
    super(readOnly);

    this.address = address;
    this.capacity = capacity;
    this.limit = capacity;
    this.position = 0;
  }

  protected DirectByteBuffer(long address, int capacity) {
    this(address, capacity, false);
  }

  public ByteBuffer asReadOnlyBuffer() {
    ByteBuffer b = new DirectByteBuffer(address, capacity, true);
    b.position(position());
    b.limit(limit());
    return b;
  }

  public ByteBuffer slice() {
    return new DirectByteBuffer(address + position, remaining(), true);
  }

  protected void doPut(int position, byte val) {
    unsafe.putByte(address + position, val);
  }

  public ByteBuffer put(ByteBuffer src) {
    if (src instanceof DirectByteBuffer) {
      checkPut(position, src.remaining(), false);

      DirectByteBuffer b = (DirectByteBuffer) src;

      unsafe.copyMemory
        (b.address + b.position, address + position, b.remaining());

      position += b.remaining();
      b.position += b.remaining();

      return this;
    } else {
      return super.put(src);
    }
  }

  public ByteBuffer put(byte[] src, int offset, int length) {
    if (offset < 0 || offset + length > src.length) {
      throw new ArrayIndexOutOfBoundsException();
    }

    checkPut(position, length, false);