| /* |
| * 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 "config.h" |
| |
| #if ENABLE(WEB_AUDIO) |
| |
| #include "platform/audio/ZeroPole.h" |
| |
| #include "platform/audio/DenormalDisabler.h" |
| |
| namespace WebCore { |
| |
| void ZeroPole::process(const float *source, float *destination, unsigned 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; |
| |
| while (framesToProcess--) { |
| float input = *source++; |
| |
| // Zero |
| float output1 = k1 * (input - zero * lastX); |
| lastX = input; |
| |
| // Pole |
| float output2 = k2 * output1 + pole * lastY; |
| lastY = output2; |
| |
| *destination++ = output2; |
| } |
| |
| // Locals to member variables. Flush denormals here so we don't |
| // slow down the inner loop above. |
| m_lastX = DenormalDisabler::flushDenormalFloatToZero(lastX); |
| m_lastY = DenormalDisabler::flushDenormalFloatToZero(lastY); |
| } |
| |
| } // namespace WebCore |
| |
| #endif // ENABLE(WEB_AUDIO) |