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PlantUML is a component that allows to quickly write diagrams from text.
There is a newer version: 1.2024.8
// THIS FILE HAS BEEN GENERATED BY A PREPROCESSOR.
/* +=======================================================================
 * |
 * |      PlantUML : a free UML diagram generator
 * |
 * +=======================================================================
 *
 * (C) Copyright 2009-2024, Arnaud Roques
 *
 * Project Info:  https://plantuml.com
 *
 * If you like this project or if you find it useful, you can support us at:
 *
 * https://plantuml.com/patreon (only 1$ per month!)
 * https://plantuml.com/liberapay (only 1€ per month!)
 * https://plantuml.com/paypal
 *
 *
 * PlantUML is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License V2.
 *
 * THE ACCOMPANYING PROGRAM IS PROVIDED UNDER THE TERMS OF THIS ECLIPSE PUBLIC
 * LICENSE ("AGREEMENT"). [GNU General Public License V2]
 *
 * ANY USE, REPRODUCTION OR DISTRIBUTION OF THE PROGRAM CONSTITUTES
 * RECIPIENT'S ACCEPTANCE OF THIS AGREEMENT.
 *
 * You may obtain a copy of the License at
 *
 * https://www.gnu.org/licenses/old-licenses/gpl-2.0.html
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * PlantUML can occasionally display sponsored or advertising messages. Those
 * messages are usually generated on welcome or error images and never on
 * functional diagrams.
 * See https://plantuml.com/professional if you want to remove them
 *
 * Images (whatever their format : PNG, SVG, EPS...) generated by running PlantUML
 * are owned by the author of their corresponding sources code (that is, their
 * textual description in PlantUML language). Those images are not covered by
 * this GPL v2 license.
 *
 * The generated images can then be used without any reference to the GPL v2 license.
 * It is not even necessary to stipulate that they have been generated with PlantUML,
 * although this will be appreciated by the PlantUML team.
 *
 * There is an exception : if the textual description in PlantUML language is also covered
 * by any license, then the generated images are logically covered
 * by the very same license.
 *
 * This is the IGY distribution (Install GraphViz by Yourself).
 * You have to install GraphViz and to setup the GRAPHVIZ_DOT environment variable
 * (see https://plantuml.com/graphviz-dot )
 *
 * Icons provided by OpenIconic :  https://useiconic.com/open
 * Archimate sprites provided by Archi :  http://www.archimatetool.com
 * Stdlib AWS provided by https://github.com/milo-minderbinder/AWS-PlantUML
 * Stdlib Icons provided https://github.com/tupadr3/plantuml-icon-font-sprites
 * ASCIIMathML (c) Peter Jipsen http://www.chapman.edu/~jipsen
 * ASCIIMathML (c) David Lippman http://www.pierce.ctc.edu/dlippman
 * CafeUndZopfli ported by Eugene Klyuchnikov https://github.com/eustas/CafeUndZopfli
 * Brotli (c) by the Brotli Authors https://github.com/google/brotli
 * Themes (c) by Brett Schwarz https://github.com/bschwarz/puml-themes
 * Twemoji (c) by Twitter at https://twemoji.twitter.com/
 *
 */
package net.sourceforge.plantuml.dedication;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.math.BigInteger;

public class QBlock {

	private final BigInteger big;

	public static QBlock read(InputStream source, int size) throws IOException {
		final byte[] block = new byte[size + 1];
		for (int i = 0; i < size; i++) {
			final int read = source.read();
			if (read == -1) {
				if (i == 0)
					return null;

				break;
			}
			block[i + 1] = (byte) read;
		}
		return new QBlock(new BigInteger(block));
	}

	public static QBlock fromBuffer(final byte[] buffer) {
		final byte[] block = new byte[buffer.length + 1];
		System.arraycopy(buffer, 0, block, 1, buffer.length);
		final BigInteger big = new BigInteger(block);
		return new QBlock(big);
	}

	public QBlock(BigInteger number) {
		this.big = number;
	}

	public QBlock change(BigInteger E, BigInteger N) {
		final BigInteger changed = big.modPow(E, N);
		return new QBlock(changed);
	}

	public byte[] getData512() {
		final byte[] nb = big.toByteArray();
		if (nb.length == 512)
			return nb;

		final byte[] result = new byte[512];
		if (nb.length < 512)
			System.arraycopy(nb, 0, result, 512 - nb.length, nb.length);
		else
			System.arraycopy(nb, nb.length - 512, result, 0, 512);

		return result;
	}

	public byte[] getDataRaw() {
		return big.toByteArray();
	}

	@Override
	public String toString() {
		return big.toByteArray().length + " " + big.toString(36);
	}

	public void write(OutputStream os, int size) throws IOException {
		final byte[] data = big.toByteArray();
		final int start = data.length - size;
		if (start < 0)
			for (int i = 0; i < -start; i++)
				os.write(0);

		for (int i = Math.max(start, 0); i < data.length; i++) {
			int b = data[i];
			os.write(b);
		}

	}

}