15c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles)/*
25c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles) * Copyright (C) 2011 Google Inc. All rights reserved.
35c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles) *
45c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles) * Redistribution and use in source and binary forms, with or without
55c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles) * modification, are permitted provided that the following conditions
65c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles) * are met:
75c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles) *
85c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles) * 1.  Redistributions of source code must retain the above copyright
95c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles) *     notice, this list of conditions and the following disclaimer.
105c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles) * 2.  Redistributions in binary form must reproduce the above copyright
115c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles) *     notice, this list of conditions and the following disclaimer in the
125c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles) *     documentation and/or other materials provided with the distribution.
135c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles) * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
145c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles) *     its contributors may be used to endorse or promote products derived
155c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles) *     from this software without specific prior written permission.
165c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles) *
175c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles) * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
185c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles) * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
195c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles) * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
205c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles) * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
215c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles) * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
225c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles) * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
235c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles) * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
245c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles) * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
255c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles) * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
265c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles) * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
275c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles) */
285c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles)
295c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles)#include "config.h"
305c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles)
315c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles)#if ENABLE(WEB_AUDIO)
325c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles)
331e202183a5dc46166763171984b285173f8585e5Torne (Richard Coles)#include "platform/audio/ZeroPole.h"
345c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles)
351e202183a5dc46166763171984b285173f8585e5Torne (Richard Coles)#include "platform/audio/DenormalDisabler.h"
365c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles)
37c1847b1379d12d0e05df27436bf19a9b1bf12deaTorne (Richard Coles)namespace blink {
385c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles)
395c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles)void ZeroPole::process(const float *source, float *destination, unsigned framesToProcess)
405c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles){
415c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles)    float zero = m_zero;
425c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles)    float pole = m_pole;
435c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles)
445c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles)    // Gain compensation to make 0dB @ 0Hz
455c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles)    const float k1 = 1 / (1 - zero);
465c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles)    const float k2 = 1 - pole;
4702772c6a72f1ee0b226341a4f4439970c29fc861Ben Murdoch
485c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles)    // Member variables to locals.
495c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles)    float lastX = m_lastX;
505c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles)    float lastY = m_lastY;
515c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles)
525c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles)    while (framesToProcess--) {
535c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles)        float input = *source++;
545c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles)
555c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles)        // Zero
565c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles)        float output1 = k1 * (input - zero * lastX);
575c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles)        lastX = input;
585c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles)
595c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles)        // Pole
605c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles)        float output2 = k2 * output1 + pole * lastY;
615c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles)        lastY = output2;
625c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles)
635c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles)        *destination++ = output2;
645c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles)    }
6502772c6a72f1ee0b226341a4f4439970c29fc861Ben Murdoch
665c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles)    // Locals to member variables. Flush denormals here so we don't
675c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles)    // slow down the inner loop above.
685c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles)    m_lastX = DenormalDisabler::flushDenormalFloatToZero(lastX);
695c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles)    m_lastY = DenormalDisabler::flushDenormalFloatToZero(lastY);
705c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles)}
715c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles)
72c1847b1379d12d0e05df27436bf19a9b1bf12deaTorne (Richard Coles)} // namespace blink
735c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles)
745c87bf8b86a7c82ef50fb7a89697d8e02e2553beTorne (Richard Coles)#endif // ENABLE(WEB_AUDIO)
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