1/*
2 * Copyright (C) 2012 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 "config.h"
30
31#if ENABLE(WEB_AUDIO)
32
33#include "platform/audio/AudioFIFO.h"
34
35namespace blink {
36
37AudioFIFO::AudioFIFO(unsigned numberOfChannels, size_t fifoLength)
38    : m_fifoAudioBus(AudioBus::create(numberOfChannels, fifoLength))
39    , m_fifoLength(fifoLength)
40    , m_framesInFifo(0)
41    , m_readIndex(0)
42    , m_writeIndex(0)
43{
44}
45
46void AudioFIFO::consume(AudioBus* destination, size_t framesToConsume)
47{
48    bool isGood = destination && (framesToConsume <= m_fifoLength) && (framesToConsume <= m_framesInFifo) && (destination->length() >= framesToConsume);
49    ASSERT(isGood);
50    if (!isGood)
51        return;
52
53    // Copy the requested number of samples to the destination.
54
55    size_t part1Length;
56    size_t part2Length;
57    findWrapLengths(m_readIndex, framesToConsume, part1Length, part2Length);
58
59    size_t numberOfChannels = m_fifoAudioBus->numberOfChannels();
60
61    for (size_t channelIndex = 0; channelIndex < numberOfChannels; ++channelIndex) {
62        float* destinationData = destination->channel(channelIndex)->mutableData();
63        const float* sourceData = m_fifoAudioBus->channel(channelIndex)->data();
64
65        bool isCopyGood = ((m_readIndex < m_fifoLength)
66                           && (m_readIndex + part1Length) <= m_fifoLength
67                           && (part1Length <= destination->length())
68                           && (part1Length + part2Length) <= destination->length());
69        ASSERT(isCopyGood);
70        if (!isCopyGood)
71            return;
72
73        memcpy(destinationData, sourceData + m_readIndex, part1Length * sizeof(*sourceData));
74        // Handle wrap around of the FIFO, if needed.
75        if (part2Length)
76            memcpy(destinationData + part1Length, sourceData, part2Length * sizeof(*sourceData));
77    }
78    m_readIndex = updateIndex(m_readIndex, framesToConsume);
79    ASSERT(m_framesInFifo >= framesToConsume);
80    m_framesInFifo -= framesToConsume;
81}
82
83void AudioFIFO::push(const AudioBus* sourceBus)
84{
85    // Copy the sourceBus into the FIFO buffer.
86
87    bool isGood = sourceBus && (m_framesInFifo + sourceBus->length() <= m_fifoLength);
88    if (!isGood)
89        return;
90
91    size_t sourceLength = sourceBus->length();
92    size_t part1Length;
93    size_t part2Length;
94    findWrapLengths(m_writeIndex, sourceLength, part1Length, part2Length);
95
96    size_t numberOfChannels = m_fifoAudioBus->numberOfChannels();
97
98    for (size_t channelIndex = 0; channelIndex < numberOfChannels; ++channelIndex) {
99        float* destination = m_fifoAudioBus->channel(channelIndex)->mutableData();
100        const float* source = sourceBus->channel(channelIndex)->data();
101
102        bool isCopyGood = ((m_writeIndex < m_fifoLength)
103                           && (m_writeIndex + part1Length) <= m_fifoLength
104                           && part2Length < m_fifoLength
105                           && part1Length + part2Length <= sourceLength);
106        ASSERT(isCopyGood);
107        if (!isCopyGood)
108            return;
109
110        memcpy(destination + m_writeIndex, source, part1Length * sizeof(*destination));
111
112        // Handle wrap around of the FIFO, if needed.
113        if (part2Length)
114            memcpy(destination, source + part1Length, part2Length * sizeof(*destination));
115    }
116
117    m_framesInFifo += sourceLength;
118    ASSERT(m_framesInFifo <= m_fifoLength);
119    m_writeIndex = updateIndex(m_writeIndex, sourceLength);
120}
121
122void AudioFIFO::findWrapLengths(size_t index, size_t size, size_t& part1Length, size_t& part2Length)
123{
124    ASSERT_WITH_SECURITY_IMPLICATION(index < m_fifoLength && size <= m_fifoLength);
125    if (index < m_fifoLength && size <= m_fifoLength) {
126        if (index + size > m_fifoLength) {
127            // Need to wrap. Figure out the length of each piece.
128            part1Length = m_fifoLength - index;
129            part2Length = size - part1Length;
130        } else {
131            // No wrap needed.
132            part1Length = size;
133            part2Length = 0;
134        }
135    } else {
136        // Invalid values for index or size. Set the part lengths to zero so nothing is copied.
137        part1Length = 0;
138        part2Length = 0;
139    }
140}
141
142} // namespace blink
143
144#endif // ENABLE(WEB_AUDIO)
145