Line data    Source code

       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             :  */
      28             : 
      29             : #include "ZeroPole.h"
      30             : 
      31             : #include "DenormalDisabler.h"
      32             : 
      33             : #include <cmath>
      34             : #include <float.h>
      35             : 
      36             : namespace WebCore {
      37             : 
      38           0 : void ZeroPole::process(const float *source, float *destination, int framesToProcess)
      39             : {
      40           0 :     float zero = m_zero;
      41           0 :     float pole = m_pole;
      42             : 
      43             :     // Gain compensation to make 0dB @ 0Hz
      44           0 :     const float k1 = 1 / (1 - zero);
      45           0 :     const float k2 = 1 - pole;
      46             : 
      47             :     // Member variables to locals.
      48           0 :     float lastX = m_lastX;
      49           0 :     float lastY = m_lastY;
      50             : 
      51           0 :     for (int i = 0; i < framesToProcess; ++i) {
      52           0 :         float input = source[i];
      53             : 
      54             :         // Zero
      55           0 :         float output1 = k1 * (input - zero * lastX);
      56           0 :         lastX = input;
      57             : 
      58             :         // Pole
      59           0 :         float output2 = k2 * output1 + pole * lastY;
      60           0 :         lastY = output2;
      61             : 
      62           0 :         destination[i] = output2;
      63             :     }
      64             : 
      65             :     // Locals to member variables. Flush denormals here so we don't
      66             :     // slow down the inner loop above.
      67             :     #ifndef HAVE_DENORMAL
      68             :     if (lastX == 0.0f && lastY != 0.0f && fabsf(lastY) < FLT_MIN) {
      69             :         // Flush future values to zero (until there is new input).
      70             :         lastY = 0.0;
      71             : 
      72             :         // Flush calculated values.
      73             :         for (int i = framesToProcess; i-- && fabsf(destination[i]) < FLT_MIN; ) {
      74             :             destination[i] = 0.0f;
      75             :         }
      76             :     }
      77             :     #endif
      78             : 
      79           0 :     m_lastX = lastX;
      80           0 :     m_lastY = lastY;
      81           0 : }
      82             : 
      83             : } // namespace WebCore