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 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
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 * 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
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package org.apache.commons.compress.archivers.zip;

Circular byte buffer.
Author:Emmanuel Bourg
Since:1.7
/** * Circular byte buffer. * * @author Emmanuel Bourg * @since 1.7 */
class CircularBuffer {
Size of the buffer
/** Size of the buffer */
private final int size;
The buffer
/** The buffer */
private final byte[] buffer;
Index of the next data to be read from the buffer
/** Index of the next data to be read from the buffer */
private int readIndex;
Index of the next data written in the buffer
/** Index of the next data written in the buffer */
private int writeIndex; CircularBuffer(final int size) { this.size = size; buffer = new byte[size]; }
Tells if a new byte can be read from the buffer.
/** * Tells if a new byte can be read from the buffer. */
public boolean available() { return readIndex != writeIndex; }
Writes a byte to the buffer.
/** * Writes a byte to the buffer. */
public void put(final int value) { buffer[writeIndex] = (byte) value; writeIndex = (writeIndex + 1) % size; }
Reads a byte from the buffer.
/** * Reads a byte from the buffer. */
public int get() { if (available()) { final int value = buffer[readIndex]; readIndex = (readIndex + 1) % size; return value & 0xFF; } return -1; }
Copy a previous interval in the buffer to the current position.
Params:
  • distance – the distance from the current write position
  • length – the number of bytes to copy
/** * Copy a previous interval in the buffer to the current position. * * @param distance the distance from the current write position * @param length the number of bytes to copy */
public void copy(final int distance, final int length) { final int pos1 = writeIndex - distance; final int pos2 = pos1 + length; for (int i = pos1; i < pos2; i++) { buffer[writeIndex] = buffer[(i + size) % size]; writeIndex = (writeIndex + 1) % size; } } }