/*
 * Copyright 2009 Phil Burk, Mobileer Inc
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *     http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.jsyn.unitgen;

import com.jsyn.engine.MultiTable;

/**
 * Band-limited square wave oscillator. This requires more CPU than a SquareOscillator but is less
 * noisy at high frequencies.
 * 
 * @author Phil Burk (C) 2009 Mobileer Inc
 */
public class SquareOscillatorBL extends SawtoothOscillatorBL {
    @Override
    protected double generateBL(MultiTable multiTable, double currentPhase,
            double positivePhaseIncrement, double flevel, int i) {
        double val1 = multiTable.calculateSawtooth(currentPhase, positivePhaseIncrement, flevel);

        /* Generate second sawtooth so we can add them together. */
        double phase2 = currentPhase + 1.0; /* 180 degrees out of phase. */
        if (phase2 >= 1.0)
            phase2 -= 2.0;
        double val2 = multiTable.calculateSawtooth(phase2, positivePhaseIncrement, flevel);

        /*
         * Need to adjust amplitude based on positive phaseInc. little less than half at
         * Nyquist/2.0!
         */
        final double STARTAMP = 0.92; /* Derived by viewing waveforms with TJ_SEEOSC */
        double scale = STARTAMP - positivePhaseIncrement;
        return scale * (val1 - val2);
    }
}