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Utililty classes for Maverick Synergy and Maverick Legacy SSH APIs

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package com.sshtools.common.util;

/*-
 * #%L
 * Utils
 * %%
 * Copyright (C) 2002 - 2024 JADAPTIVE Limited
 * %%
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Lesser Public License for more details.
 * 
 * You should have received a copy of the GNU General Lesser Public
 * License along with this program.  If not, see
 * .
 * #L%
 */

import java.io.IOException;

/**
 *
 *
 * @author $author$
 */
public class SimpleASNReader {
  private byte[] data;
  private int offset;

  /**
   * Creates a new SimpleASNReader object.
   *
   * @param data
   */
  public SimpleASNReader(byte[] data) {
    this.data = data;
    this.offset = 0;
  }

  /**
   *
   *
   * @param b
   *
   * @throws IOException
   */
  public void assertByte(int b) throws IOException {
    int x = getByte();

    if (x != b) {
      throw new IOException("Assertion failed, next byte value is "
                            + Integer.toHexString(x) + " instead of asserted "
                            + Integer.toHexString(b));
    }
  }

  /**
   *
   *
   * @return
   */
  public int getByte() {
    return data[offset++] & 0xff;
  }

  /**
   *
   *
   * @return
   */
  public byte[] getData() {
    int length = getLength();

    return getData(length);
  }

  /**
   *
   *
   * @return
   */
  public int getLength() {
    int b = data[offset++] & 0xff;

    if ( (b & 0x80) != 0) {
      int length = 0;

      for (int bytes = b & 0x7f; bytes > 0; bytes--) {
        length <<= 8;
        length |= (data[offset++] & 0xff);
      }

      return length;
    }

    return b;
  }

  private byte[] getData(int length) {
    byte[] result = new byte[length];
    System.arraycopy(data, offset, result, 0, length);
    offset += length;

    return result;
  }

  /**
   *
   *
   * @return
   */
  public boolean hasMoreData() {
    return offset < data.length;
  }
}