/*

 * Copyright (C) 2011 Google Inc. All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 * 1.  Redistributions of source code must retain the above copyright

 *     notice, this list of conditions and the following disclaimer.

 * 2.  Redistributions in binary form must reproduce the above copyright

 *     notice, this list of conditions and the following disclaimer in the

 *     documentation and/or other materials provided with the distribution.

 * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of

 *     its contributors may be used to endorse or promote products derived

 *     from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY

 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED

 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE

 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY

 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES

 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;

 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND

 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF

 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

#include "ZeroPole.h"

#include "DenormalDisabler.h"

#include <cmath>

#include <float.h>

namespace WebCore {

void ZeroPole::process(const float *source, float *destination, int framesToProcess)

{

    float zero = m_zero;

    float pole = m_pole;

    // Gain compensation to make 0dB @ 0Hz

    const float k1 = 1 / (1 - zero);

    const float k2 = 1 - pole;

    // Member variables to locals.

    float lastX = m_lastX;

    float lastY = m_lastY;

    for (int i = 0; i < framesToProcess; ++i) {

        float input = source[i];

        // Zero

        float output1 = k1 * (input - zero * lastX);

        lastX = input;

        // Pole

        float output2 = k2 * output1 + pole * lastY;

        lastY = output2;

        destination[i] = output2;

    }

    // Locals to member variables. Flush denormals here so we don't

    // slow down the inner loop above.

    #ifndef HAVE_DENORMAL

    if (lastX == 0.0f && lastY != 0.0f && fabsf(lastY) < FLT_MIN) {

        // Flush future values to zero (until there is new input).

        lastY = 0.0;

        // Flush calculated values.

        for (int i = framesToProcess; i-- && fabsf(destination[i]) < FLT_MIN; ) {

            destination[i] = 0.0f;

        }

    }

    #endif

    m_lastX = lastX;

    m_lastY = lastY;

}

} // namespace WebCore