chromium/third_party/blink/renderer/platform/audio/iir_filter.cc

// Copyright 2016 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifdef UNSAFE_BUFFERS_BUILD
// TODO(crbug.com/351564777): Remove this and convert code to safer constructs.
#pragma allow_unsafe_buffers
#endif

#include "third_party/blink/renderer/platform/audio/iir_filter.h"

#include <algorithm>
#include <complex>

#include "third_party/blink/renderer/platform/audio/audio_utilities.h"
#include "third_party/blink/renderer/platform/audio/vector_math.h"
#include "third_party/blink/renderer/platform/wtf/math_extras.h"
#include "third_party/fdlibm/ieee754.h"

namespace blink {

// The length of the memory buffers for the IIR filter.  This MUST be a power of
// two and must be greater than the possible length of the filter coefficients.
const int kBufferLength = …;
static_assert …;

IIRFilter::IIRFilter(const AudioDoubleArray* feedforward,
                     const AudioDoubleArray* feedback)
    : … { … }

IIRFilter::~IIRFilter() = default;

void IIRFilter::Reset() { … }

static std::complex<double> EvaluatePolynomial(const double* coef,
                                               std::complex<double> z,
                                               int order) { … }

void IIRFilter::Process(const float* source_p,
                        float* dest_p,
                        uint32_t frames_to_process) { … }

void IIRFilter::GetFrequencyResponse(int n_frequencies,
                                     const float* frequency,
                                     float* mag_response,
                                     float* phase_response) { … }

double IIRFilter::TailTime(double sample_rate,
                           bool is_filter_stable,
                           unsigned render_quantum_frames) { … }

}  // namespace blink