The Tor Browser: content/media/webaudio/blink/ZeroPole.cpp@6474c204b198

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

     1 /*

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

     3  *

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

     5  * modification, are permitted provided that the following conditions

     6  * are met:

     7  *

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

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

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

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

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

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

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

    15  *     from this software without specific prior written permission.

    16  *

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

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

    19  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE

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

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

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

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

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

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

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

    27  */

    29 #include "ZeroPole.h"

    31 #include <cmath>

    32 #include <float.h>

    34 namespace WebCore {

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

    37 {

    38     float zero = m_zero;

    39     float pole = m_pole;

    41     // Gain compensation to make 0dB @ 0Hz

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

    43     const float k2 = 1 - pole;

    45     // Member variables to locals.

    46     float lastX = m_lastX;

    47     float lastY = m_lastY;

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

    50         float input = source[i];

    52         // Zero

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

    54         lastX = input;

    56         // Pole

    57         float output2 = k2 * output1 + pole * lastY;

    58         lastY = output2;

    60         destination[i] = output2;

    61     }

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

    64     // slow down the inner loop above.

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

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

    67         lastY = 0.0;

    68         // Flush calculated values.

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

    70             destination[i] = 0.0f;

    71         }

    72     }

    74     m_lastX = lastX;

    75     m_lastY = lastY;

    76 }

    78 } // namespace WebCore

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