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/*
 * Copyright (c) 1998-2018 University Corporation for Atmospheric Research/Unidata
 * See LICENSE for license information.
 */
package ucar.unidata.io;

import java.io.*;
import java.nio.channels.FileChannel;
import java.nio.MappedByteBuffer;

/**
 * Use NIO MappedByteBuffer to implement a RandomAccessFile.
 * Limited to 2G size. Not currently used - NOT UP TO DATE DO NOT USE
 * 
 * @deprecated not part of public API.
 */
@Deprecated
public class MMapRandomAccessFile extends RandomAccessFile {

  private MappedByteBuffer source;

  /**
   * Constructor for in-memory "files"
   * 
   * @param location used as a name
   * @param mode the open mode
   * @throws java.io.IOException on error
   */
  public MMapRandomAccessFile(String location, String mode) throws IOException {
    super(location, mode, 1);
    FileChannel channel = file.getChannel();
    source = channel.map(readonly ? FileChannel.MapMode.READ_ONLY : FileChannel.MapMode.READ_WRITE, (long) 0,
        channel.size());
    // channel.close();

    bufferStart = 0;
    dataSize = (int) channel.size();
    dataEnd = channel.size();
    filePosition = 0;
    buffer = null;
    endOfFile = false;
  }


  public void flush() {
    if (bufferModified) {
      source.force();
      bufferModified = false;
    }
  }

  public long length() {
    return dataEnd;
  }

  public void seek(long pos) {
    filePosition = pos;
    if (filePosition < dataEnd)
      source.position((int) filePosition);
    else
      endOfFile = true;
  }

  public void unread() {
    seek(filePosition - 1);
  }

  public int read() {
    // If the file position is within the data, return the byte...
    if (filePosition < dataEnd) {
      filePosition++;
      return source.get() & 0xff;

    } else {
      return -1;
    }
  }

  public int readBytes(byte[] dst, int offset, int length) {
    if (endOfFile)
      return -1;

    length = (int) Math.min(length, dataEnd - filePosition);
    if (length > 0) {
      source.get(dst, offset, length);
      filePosition += length;
    }
    return length;
  }

  public void write(int b) {
    source.put((byte) b);
    filePosition++;
    bufferModified = true;
  }

  public void writeBytes(byte[] dst, int offset, int length) {
    source.put(dst, offset, length);
    filePosition += length;
  }

}