| /* |
| * 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 org.apache.commons.compress.archivers.zip; |
| |
| /** |
| * Circular byte buffer. |
| * |
| * @author Emmanuel Bourg |
| * @since 1.7 |
| */ |
| class CircularBuffer { |
| |
| /** Size of the buffer */ |
| private final int size; |
| |
| /** The buffer */ |
| private final byte[] buffer; |
| |
| /** Index of the next data to be read from the buffer */ |
| private int readIndex; |
| |
| /** 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. |
| */ |
| public boolean available() { |
| return readIndex != writeIndex; |
| } |
| |
| /** |
| * 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. |
| */ |
| 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. |
| * |
| * @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; |
| } |
| } |
| } |