BaseLpcDataFetcher.java

/*
  BaseLpcDataFetcher.java

  (c) 2012-2014 Edward 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.engine.speech;

import v9t9.common.speech.ISpeechPhraseListener;
import ejs.base.utils.ListenerList;
import ejs.base.utils.ListenerList.IFire;

public abstract class BaseLpcDataFetcher implements ILPCDataFetcher {
	protected ILPCByteFetcher byteFetcher;
	protected int bit;
	private ListenerList<ISpeechPhraseListener> listeners;
	
	/**
	 * 
	 */
	public BaseLpcDataFetcher() {
	}
	
	/* (non-Javadoc)
	 * @see v9t9.engine.speech.ILPCDataFetcher#setPhraseListeners(ejs.base.utils.ListenerList)
	 */
	@Override
	public void setPhraseListeners(ListenerList<ISpeechPhraseListener> listeners) {
		this.listeners = listeners;
	}
	
	/**
	 * @param byteFetcher the byteFetcher to set
	 */
	public void setByteFetcher(ILPCByteFetcher byteFetcher) {
		this.byteFetcher = byteFetcher;
	}
	
	public void reset() {
		bit = 0;
	}
	
	protected int extractBits(int cur, int bits) {
		/* Get the bits we want. */
		cur = (cur << bit + 16) >>> (32 - bits);

		/* Adjust bit ptr */
		bit = (bit + bits) & 7;

		return cur;
	}
	

	/**
	 * Fetch so many bits.
	 */
	@Override
	public int fetch(int bits) {
		int cur;

		if (bit + bits >= 8) { /* we will cross into the next byte */
			cur = byteFetcher.read();
			cur <<= 8;
			
			byte next = byteFetcher.peek();
			fireByteAdded(next);
			
			cur |= next & 0xff; /*
								 * we can't read more than 6 bits, so no
								 * poss of crossing TWO bytes
								 */
		} else {
			final byte next = byteFetcher.peek();
			if (bit == 0) {
				fireByteAdded(next);
			}
			cur = next << 8;
		}

		return extractBits(cur, bits);
	}

	/**
	 * @param next
	 */
	private void fireByteAdded(final byte next) {
		if (listeners != null) {
			listeners.fire(new IFire<ISpeechPhraseListener>() {

				@Override
				public void fire(ISpeechPhraseListener listener) {
					listener.phraseByteAdded(next);
				}
			});
		}
		
	}

	/* (non-Javadoc)
	 * @see v9t9.engine.speech.ILPCDataFetcher#isDone()
	 */
	@Override
	public boolean isDone() {
		return false;
	}
}