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 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 "config.h"
30
31#if ENABLE(WEB_AUDIO)
32
33#include "ZeroPole.h"
34
35#include "DenormalDisabler.h"
36
37namespace WebCore {
38
39void ZeroPole::process(const float *source, float *destination, unsigned framesToProcess)
40{
41 float zero = m_zero;
42 float pole = m_pole;
43
44 // Gain compensation to make 0dB @ 0Hz
45 const float k1 = 1 / (1 - zero);
46 const float k2 = 1 - pole;
47
48 // Member variables to locals.
49 float lastX = m_lastX;
50 float lastY = m_lastY;
51
52 while (framesToProcess--) {
53 float input = *source++;
54
55 // Zero
56 float output1 = k1 * (input - zero * lastX);
57 lastX = input;
58
59 // Pole
60 float output2 = k2 * output1 + pole * lastY;
61 lastY = output2;
62
63 *destination++ = output2;
64 }
65
66 // Locals to member variables. Flush denormals here so we don't
67 // slow down the inner loop above.
68 m_lastX = DenormalDisabler::flushDenormalFloatToZero(lastX);
69 m_lastY = DenormalDisabler::flushDenormalFloatToZero(lastY);
70}
71
72} // namespace WebCore
73
74#endif // ENABLE(WEB_AUDIO)
75