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78 lines
2.2 KiB
C++
78 lines
2.2 KiB
C++
//
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// SampleSource.hpp
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// Clock Signal
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//
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// Created by Thomas Harte on 17/12/2017.
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// Copyright 2017 Thomas Harte. All rights reserved.
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//
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#ifndef SampleSource_hpp
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#define SampleSource_hpp
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#include <cstddef>
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#include <cstdint>
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namespace Outputs {
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namespace Speaker {
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/*!
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A sample source is something that can provide a stream of audio.
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This optional base class provides the interface expected to be exposed
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by the template parameter to LowpassSpeaker.
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*/
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class SampleSource {
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public:
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/*!
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Should write the next @c number_of_samples to @c target.
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*/
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void get_samples([[maybe_unused]] std::size_t number_of_samples, [[maybe_unused]] std::int16_t *target) {}
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/*!
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Should skip the next @c number_of_samples. Subclasses of this SampleSource
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need not implement this if it would no more efficient to do so than it is
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merely to call get_samples and throw the result away, as per the default
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implementation below.
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*/
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void skip_samples(const std::size_t number_of_samples) {
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std::int16_t scratch_pad[number_of_samples];
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get_samples(number_of_samples, scratch_pad);
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}
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/*!
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@returns @c true if it is trivially true that a call to get_samples would just
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fill the target with zeroes; @c false if a call might return all zeroes or
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might not.
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*/
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bool is_zero_level() const {
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return false;
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}
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/*!
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Sets the proper output range for this sample source; it should write values
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between 0 and volume.
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*/
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void set_sample_volume_range([[maybe_unused]] std::int16_t volume) {}
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/*!
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Indicates whether this component will write stereo samples.
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*/
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static constexpr bool get_is_stereo() { return false; }
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/*!
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Permits a sample source to declare that, averaged over time, it will use only
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a certain proportion of the allocated volume range. This commonly happens
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in sample sources that use a time-multiplexed sound output — for example, if
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one were to output only every other sample then it would return 0.5.
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This is permitted to vary over time but there is no contract as to when it will be
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used by a speaker. If it varies, it should do so very infrequently and only to
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represent changes in hardware configuration.
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*/
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double get_average_output_peak() const { return 1.0; }
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};
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}
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}
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#endif /* SampleSource_hpp */
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