/*

 * Copyright (c) 2007, Oracle and/or its affiliates. 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.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.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.

 *

 * @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;

    float controlrate;

    public void init(float samplerate, float controlrate) {

        this.controlrate = controlrate;

    }

    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 / controlrate;

            if (silentcounter > 60) {

                if (!mix) {

                    bufferLout.clear();

                    if (bufferRout != null) 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() {

    }

}