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/*
Copyright 2018 Google Inc. All Rights Reserved.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS-IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
#ifndef RESONANCE_AUDIO_BASE_CHANNEL_VIEW_H_
#define RESONANCE_AUDIO_BASE_CHANNEL_VIEW_H_
#include <algorithm>
#include <cstring>
#include <vector>
#include "base/logging.h"
namespace vraudio {
// Provides an interface to a single audio channel in |AudioBuffer|. Note that a
// |ChannelView| instance does not own the data it is initialized with.
class ChannelView {
public:
// Array subscript operator returning a reference.
float& operator[](size_t index) {
DCHECK(enabled_);
DCHECK_LT(index, size_);
return *(begin() + index);
}
// Const array subscript operator returning a const reference.
const float& operator[](size_t index) const {
DCHECK(enabled_);
DCHECK_LT(index, size_);
return *(begin() + index);
}
// Returns the size of the channel in samples.
size_t size() const { return size_; }
// Returns a float pointer to the begin of the channel data.
float* begin() {
DCHECK(enabled_);
return begin_itr_;
}
// Returns a float pointer to the end of the channel data.
float* end() {
DCHECK(enabled_);
return begin_itr_ + size_;
}
// Returns a const float pointer to the begin of the channel data.
const float* begin() const {
DCHECK(enabled_);
return begin_itr_;
}
// Returns a const float pointer to the end of the channel data.
const float* end() const {
DCHECK(enabled_);
return begin_itr_ + size_;
}
// Copy assignment from float vector.
ChannelView& operator=(const std::vector<float>& other) {
DCHECK(enabled_);
DCHECK_EQ(other.size(), size_);
memcpy(begin(), other.data(), sizeof(float) * size_);
return *this;
}
// Copy assignment from ChannelView.
ChannelView& operator=(const ChannelView& other) {
if (this != &other) {
DCHECK(enabled_);
DCHECK_EQ(other.size(), size_);
memcpy(begin(), other.begin(), sizeof(float) * size_);
}
return *this;
}
// Adds a |ChannelView| to this |ChannelView|.
ChannelView& operator+=(const ChannelView& other);
// Subtracts a |ChannelView| from this |ChannelView|.
ChannelView& operator-=(const ChannelView& other);
// Pointwise multiplies a |ChannelView| with this |Channelview|.
ChannelView& operator*=(const ChannelView& other);
// Fills channel buffer with zeros.
void Clear() {
DCHECK(enabled_);
memset(begin(), 0, sizeof(float) * size_);
}
// Allows for disabling the channel to prevent access to the channel data and
// channel iterators. It is used in the |Mixer| class to prevent the copies of
// silence |ChannelView|s. Note that |ChannelView| are enabled by default.
//
// @param enabled True to enable the channel.
void SetEnabled(bool enabled) { enabled_ = enabled; }
// Returns true if |ChannelView| is enabled.
//
// @return State of |enabled_| flag.
bool IsEnabled() const { return enabled_; }
private:
friend class AudioBuffer;
// Constructor is initialized with a float pointer to the first sample and the
// size of chunk of planar channel data.
ChannelView(float* begin_itr, size_t size)
: begin_itr_(begin_itr), size_(size), enabled_(true) {}
// Iterator of first and last element in channel.
float* const begin_itr_;
// Channel size.
const size_t size_;
// Flag indicating if the channel is enabled.
bool enabled_;
};
} // namespace vraudio
#endif // RESONANCE_AUDIO_BASE_CHANNEL_VIEW_H_
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