IOBuffer.java

/*
  IOBuffer.java

  (c) 2014 Ed Swartz

  All rights reserved. This program and the accompanying materials
  are made available under the terms of the Eclipse Public License v1.0
  which accompanies this distribution, and is available at
  http://www.eclipse.org/legal/epl-v10.html
 */
package v9t9.common.dsr;

import java.io.ByteArrayOutputStream;
import java.util.Arrays;

public class IOBuffer {
	final int bufSiz;
	final int bufMask;
	public IOBuffer(int size) {
		this.bufSiz = size;
		this.bufMask = size - 1;
		if ((bufSiz & bufMask) != 0)
			throw new IllegalArgumentException();
		buf = new byte[bufSiz];
	}

	/* (non-Javadoc)
	 * @see java.lang.Object#toString()
	 */
	@Override
	public String toString() {
		StringBuilder sb = new StringBuilder();
		int idx = st;
		while (idx != en) {
			sb.append((char) buf[idx]);
			if (++idx == bufSiz)
				idx = 0;
		}
		return st + "/" + en + "=" + sb;
	}
	public synchronized boolean isEmpty() {
		return st == en;
	}
	public synchronized boolean isFull() {
		if (st == ((en + 1) & bufMask))
			return true;
		return false;
	}
	public synchronized int getLeft() {
		return ((bufSiz - st + en) & bufMask);
	}

	private byte buf[];
	private int	st,en;			// pointers to ring
	
	/**
	 * @return the buf
	 */
	public byte[] getBuf() {
		return buf;
	}
	/**
	 * @return the st
	 */
	public synchronized int getSt() {
		return st;
	}
	/**
	 * @return the en
	 */
	public synchronized int getEn() {
		return en;
	}
	/**
	 * 
	 */
	public synchronized void clear() {
		Arrays.fill(buf, (byte) 0);
		st = en = 0;
	}
	/**
	 * @param ch
	 */
	public synchronized void add(byte ch) {
		// Put char in buffer.  Kill most recent char if full.
		if (!isFull()) {
			buf[en] = ch;
			en = (en + 1) & bufMask;
		} else {
			buf[(en - 1 + bufSiz) & bufMask] = ch;
		}
		
	}
	/**
	 * @return
	 */
	public synchronized byte take() {
		byte ch;
		if (!isEmpty()) {
			ch = buf[st];
			st = (st + 1) & bufMask;
		} else {
			ch = buf[(st - 1 + bufSiz) & bufMask];
		}
		return ch;
	}

	/**
	 * @return
	 */
	public byte[] takeAll() {
		final ByteArrayOutputStream bos = new ByteArrayOutputStream();
		while (!isEmpty()) {
			byte b = take();
			bos.write(b);
		}
		return bos.toByteArray();
	}
}