com.bytezone.dm3270.buffers.AbstractBuffer Maven / Gradle / Ivy

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This is a trimmed down version of https://github.com/dmolony/dm3270 to be used as TN3270 client library

There is a newer version: 0.15-lib

package com.bytezone.dm3270.buffers;

public abstract class AbstractBuffer implements Buffer {

  protected byte[] data;

  public AbstractBuffer() {
    data = new byte[0];
  }

  public AbstractBuffer(byte[] buffer, int offset, int length) {
    data = new byte[length];
    System.arraycopy(buffer, offset, data, 0, length);
  }

  @Override
  public byte[] getData() {
    return data;
  }

  @Override
  public int size() {
    return data.length;
  }

  @Override
  public byte[] getTelnetData() {
    int length = data.length + countFF(data) + 2; // allow for expanded 0xFF and IAC/EOR
    byte[] buffer = new byte[length];
    copyAndExpand(data, buffer);
    buffer[--length] = (byte) 0xEF;     // EOR
    buffer[--length] = (byte) 0xFF;     // IAC
    return buffer;
  }

  protected int countFF(byte[] buffer) {
    int count = 0;
    for (byte b : buffer) {
      if (b == (byte) 0xFF) {
        count++;
      }
    }
    return count;
  }

  protected void copyAndExpand(byte[] source, byte[] dest) {
    int ptr = 0;
    for (byte b : source) {
      dest[ptr++] = b;
      if (b == (byte) 0xFF) {
        dest[ptr++] = b;
      }
    }
  }

}