/*
 * Copyright 2007 Sun Microsystems, Inc.  All Rights Reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Sun designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Sun in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 */

package com.sun.media.sound;

/**
 * 
 * A simple look-ahead volume limiter with very fast attack and fast release.
 * This filter is used for preventing clipping.
 * 
 * @version %I%, %E%
 * @author Karl Helgason
 */
public class SoftLimiter implements SoftAudioProcessor {

	float lastmax = 0;

	float gain = 1;

	float[] temp_bufferL;

	float[] temp_bufferR;

	boolean mix = false;

	SoftAudioBuffer bufferL;

	SoftAudioBuffer bufferR;

	SoftAudioBuffer bufferLout;

	SoftAudioBuffer bufferRout;

	SoftSynthesizer synth;

	public void init(SoftSynthesizer synth) {
		this.synth = synth;
	}

	public void setInput(int pin, SoftAudioBuffer input) {
		if (pin == 0)
			bufferL = input;
		if (pin == 1)
			bufferR = input;
	}

	public void setOutput(int pin, SoftAudioBuffer output) {
		if (pin == 0)
			bufferLout = output;
		if (pin == 1)
			bufferRout = output;
	}

	public void setMixMode(boolean mix) {
		this.mix = mix;
	}

	public void globalParameterControlChange(int[] slothpath, long param,
			long value) {

	}

	double silentcounter = 0;

	public void processAudio() {
		if (this.bufferL.isSilent()
				&& (this.bufferR == null || this.bufferR.isSilent())) {
			silentcounter += 1 / synth.getControlRate();

			if (silentcounter > 60) {
				if (!mix) {
					bufferLout.clear();
					bufferRout.clear();
				}
				return;
			}
		} else
			silentcounter = 0;

		float[] bufferL = this.bufferL.array();
		float[] bufferR = this.bufferR == null ? null : this.bufferR.array();
		float[] bufferLout = this.bufferLout.array();
		float[] bufferRout = this.bufferRout == null ? null : this.bufferRout
				.array();

		if (temp_bufferL == null || temp_bufferL.length < bufferL.length)
			temp_bufferL = new float[bufferL.length];
		if (bufferR != null)
			if (temp_bufferR == null || temp_bufferR.length < bufferR.length)
				temp_bufferR = new float[bufferR.length];

		float max = 0;
		int len = bufferL.length;

		if (bufferR == null)
			for (int i = 0; i < len; i++) {
				if (bufferL[i] > max)
					max = bufferL[i];
				if (-bufferL[i] > max)
					max = -bufferL[i];
			}
		else
			for (int i = 0; i < len; i++) {
				if (bufferL[i] > max)
					max = bufferL[i];
				if (bufferR[i] > max)
					max = bufferR[i];
				if (-bufferL[i] > max)
					max = -bufferL[i];
				if (-bufferR[i] > max)
					max = -bufferR[i];
			}

		float lmax = lastmax;
		lastmax = max;
		if (lmax > max)
			max = lmax;

		float newgain = 1;
		if (max > 0.99f)
			newgain = 0.99f / max;
		else
			newgain = 1;

		if (newgain > gain)
			newgain = (newgain + gain * 9) / 10f;

		float gaindelta = (newgain - gain) / len;
		if (mix) {
			if (bufferR == null)
				for (int i = 0; i < len; i++) {
					gain += gaindelta;
					float bL = bufferL[i];
					float tL = temp_bufferL[i];
					temp_bufferL[i] = bL;
					bufferLout[i] += tL * gain;
				}
			else
				for (int i = 0; i < len; i++) {
					gain += gaindelta;
					float bL = bufferL[i];
					float bR = bufferR[i];
					float tL = temp_bufferL[i];
					float tR = temp_bufferR[i];
					temp_bufferL[i] = bL;
					temp_bufferR[i] = bR;
					bufferLout[i] += tL * gain;
					bufferRout[i] += tR * gain;
				}

		} else {
			if (bufferR == null)
				for (int i = 0; i < len; i++) {
					gain += gaindelta;
					float bL = bufferL[i];
					float tL = temp_bufferL[i];
					temp_bufferL[i] = bL;
					bufferLout[i] = tL * gain;
				}
			else
				for (int i = 0; i < len; i++) {
					gain += gaindelta;
					float bL = bufferL[i];
					float bR = bufferR[i];
					float tL = temp_bufferL[i];
					float tR = temp_bufferR[i];
					temp_bufferL[i] = bL;
					temp_bufferR[i] = bR;
					bufferLout[i] = tL * gain;
					bufferRout[i] = tR * gain;
				}

		}
		gain = newgain;
	}

	public void processControlLogic() {
	}

}