mirror of
https://github.com/RGBCube/serenity
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19a4b820c4
This has been overkill from the start, and it has been bugging me for a long time. With this change, we're probably a bit slower on most platforms but save huge amounts of space with all in-memory sample datastructures.
43 lines
959 B
C++
43 lines
959 B
C++
/*
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* Copyright (c) 2021, Arne Elster <arne@elster.li>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <AK/Array.h>
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#include <AK/Math.h>
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#include <AK/Span.h>
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namespace LibDSP {
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template<size_t N>
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requires(N % 2 == 0) class MDCT {
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public:
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constexpr MDCT()
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{
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for (size_t n = 0; n < N; n++) {
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for (size_t k = 0; k < N / 2; k++) {
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m_phi[n][k] = AK::cos<float>(AK::Pi<float> / (2 * N) * (2 * static_cast<float>(n) + 1 + N / 2.0f) * static_cast<float>(2 * k + 1));
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}
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}
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}
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void transform(Span<float const> data, Span<float> output)
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{
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assert(N == 2 * data.size());
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assert(N == output.size());
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for (size_t n = 0; n < N; n++) {
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output[n] = 0;
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for (size_t k = 0; k < N / 2; k++) {
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output[n] += data[k] * m_phi[n][k];
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}
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}
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}
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private:
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Array<Array<float, N / 2>, N> m_phi;
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};
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}
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