SeptetPackingOutputStream.java

/*
 * Copyright (c) 2020, Stein Eldar Johnsen
 *
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * 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.
 */
package net.morimekta.io;

import java.io.IOException;
import java.io.OutputStream;

/**
 * An output stream that assumes each written byte is a septet (not an octet),
 * and packs each septet onto each other to make it more compact.
 */
public class SeptetPackingOutputStream extends OutputStream {
    private BitPackingOutputStream out;

    /**
     * Create a septet packing output stream.
     *
     * @param out Output stream to write packed bytes to.
     */
    public SeptetPackingOutputStream(OutputStream out) {
        this.out = out instanceof BitPackingOutputStream
                   ? (BitPackingOutputStream) out
                   : new BitPackingOutputStream(out);
    }

    @Override
    public void write(int septet) throws IOException {
        if (out == null) {
            throw new IOException("Writing to closed stream");
        }
        out.writeBits(7, septet % 0x7F);
    }

    @Override
    public void close() throws IOException {
        if (out != null) {
            try {
                out.close();
            } finally {
                out = null;
            }
        }
    }

    @Override
    public void flush() throws IOException {
        if (out != null) {
            out.flush();
        }
    }
}