JDK8/Java8源码在线阅读

/*
 * Copyright (c) 2007, 2013, 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;

/**
 * LFO control signal generator.
 *
 * @author Karl Helgason
 */
public final class SoftLowFrequencyOscillator implements SoftProcess {

    private final int max_count = 10;
    private int used_count = 0;
    private final double[][] out = new double[max_count][1];
    private final double[][] delay = new double[max_count][1];
    private final double[][] delay2 = new double[max_count][1];
    private final double[][] freq = new double[max_count][1];
    private final int[] delay_counter = new int[max_count];
    private final double[] sin_phase = new double[max_count];
    private final double[] sin_stepfreq = new double[max_count];
    private final double[] sin_step = new double[max_count];
    private double control_time = 0;
    private double sin_factor = 0;
    private static final double PI2 = 2.0 * Math.PI;

    public SoftLowFrequencyOscillator() {
        // If sin_step is 0 then sin_stepfreq must be -INF
        for (int i = 0; i < sin_stepfreq.length; i++) {
            sin_stepfreq[i] = Double.NEGATIVE_INFINITY;
        }
    }

    public void reset() {
        for (int i = 0; i < used_count; i++) {
            out[i][0] = 0;
            delay[i][0] = 0;
            delay2[i][0] = 0;
            freq[i][0] = 0;
            delay_counter[i] = 0;
            sin_phase[i] = 0;
            // If sin_step is 0 then sin_stepfreq must be -INF
            sin_stepfreq[i] = Double.NEGATIVE_INFINITY;
            sin_step[i] = 0;
        }
        used_count = 0;
    }

    public void init(SoftSynthesizer synth) {
        control_time = 1.0 / synth.getControlRate();
        sin_factor = control_time * 2 * Math.PI;
        for (int i = 0; i < used_count; i++) {
            delay_counter[i] = (int)(Math.pow(2,
                    this.delay[i][0] / 1200.0) / control_time);
            delay_counter[i] += (int)(delay2[i][0] / (control_time * 1000));
        }
        processControlLogic();
    }

    public void processControlLogic() {
        for (int i = 0; i < used_count; i++) {
            if (delay_counter[i] > 0) {
                delay_counter[i]--;
                out[i][0] = 0.5;
            } else {
                double f = freq[i][0];

                if (sin_stepfreq[i] != f) {
                    sin_stepfreq[i] = f;
                    double fr = 440.0 * Math.exp(
                            (f - 6900.0) * (Math.log(2) / 1200.0));
                    sin_step[i] = fr * sin_factor;
                }
                /*
                double fr = 440.0 * Math.pow(2.0,
                (freq[i][0] - 6900.0) / 1200.0);
                sin_phase[i] += fr * sin_factor;
                 */
                /*
                sin_phase[i] += sin_step[i];
                while (sin_phase[i] > PI2)
                sin_phase[i] -= PI2;
                out[i][0] = 0.5 + Math.sin(sin_phase[i]) * 0.5;
                 */
                double p = sin_phase[i];
                p += sin_step[i];
                while (p > PI2)
                    p -= PI2;
                out[i][0] = 0.5 + Math.sin(p) * 0.5;

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