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/*



Copyright (C) 2000 Andrew Sorensen & Andrew Brown

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or any
later version.

This program 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 for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

*/

package jm.audio.synth;

import jm.audio.AOException;
import jm.audio.AudioObject;

/**
 * Tap Delay ...
 *
 * @author Andrew Sorensen
 * @version 1.0, Sun Feb 25 18:42:46  2001
 */

public final class TapDelay extends AudioObject {
    //The gain of this comb filter
    private float decay;

    //The delay (in samples) to use with this comb filter
    private int delay;

    //Number of samples to delay by
    private float[] delayLine;

    //Delay line current index
    private int delayIndex;

    //number of taps in this delay line
    private int taps;

    //number of samples which delay is equal to
    private int sampleDelay;

    //----------------------------------------------
    // Constructors
    //----------------------------------------------

    /**
     * @param delay delay in milliseconds
     */
    public TapDelay(AudioObject ao, int delay, int taps) {
        this(ao, delay, taps, 0.5);
    }

    /**
     * @param delay delay in milliseconds
     * @param gain  as a percent
     */
    public TapDelay(AudioObject ao, int delay, int taps, double decay) {
        super(ao, "[Tap Delay]");
        this.finished = false;
        this.decay = (float) decay;
        this.delay = delay;
        this.taps = taps;
    }

    //----------------------------------------------
    // Methods
    //----------------------------------------------

    /**
     * @param buffer any number of incoming samples
     */
    public int work(float[] buffer) throws AOException {
        int returned = buffer.length;
        if (!this.inst.finishedNewData && this.inst.getFinished()) returned = this.previous[0].nextWork(buffer);
        int i = 0;
        float max = 0.0f;
        for (; i < returned; i++) {
            for (int k = 1; k <= taps; k++) {
                int tapIndex = delayIndex + (sampleDelay * this.channels * k);
                if (tapIndex >= delayLine.length) tapIndex -= delayLine.length;
                delayLine[tapIndex] += buffer[i] * (decay / k);
            }
            buffer[i] += delayLine[delayIndex];
            delayLine[delayIndex] = 0.0f;
            delayIndex++;
            if (delayIndex >= delayLine.length) {
                delayIndex = 0;
            }
            if (max < buffer[i]) max = buffer[i];
        }
        if (this.inst.iterations <= (0 - delayLine.length)) {
            this.finished = true;
        }
        return i;
    }

    /**
     *
     */
    public void build() {
        if (delayLine == null) {
            this.sampleDelay = (int) (((float) this.delay / 1000.0f) * (float) this.sampleRate);
            this.delayLine = new float[sampleDelay * this.channels * taps];
            this.delayIndex = 0;
        }
        this.finished = false;
    }
}