delay_interp.h

// Copyright (C) 2025 Alexandre St-Onge
// SPDX-License-Identifier: MIT
#pragma once
 
#include "sffdn/audio_buffer.h"
#include "sffdn/audio_processor.h"
#include "sffdn/delay.h"
#include "sffdn/filter.h"
#include "sffdn/types.h"
 
#include <array>
#include <cstddef>
#include <cstdint>
 
namespace sfFDN
{
 
class DelayInterp : public AudioProcessor
{
  public:
    DelayInterp(const DelayOptions& config = {});
 
    void Clear() override;
 
    uint32_t GetMaximumDelay() const;
 
    void SetMaximumDelay(uint32_t delay);
 
    void SetDelay(float delay) noexcept SFFDN_NONBLOCKING;
 
    float GetDelay() const;
 
    float Tick(float input) noexcept SFFDN_NONBLOCKING;
 
    float NextOut() noexcept SFFDN_NONBLOCKING;
 
    void Advance(float input) noexcept SFFDN_NONBLOCKING;
 
    float TapOut(uint32_t tap) const noexcept SFFDN_NONBLOCKING;
 
    void Process(const AudioBuffer& input, AudioBuffer& output) noexcept SFFDN_NONBLOCKING override;
 
    bool AddNextInputs(std::span<const float> input) noexcept SFFDN_NONBLOCKING;
 
    void GetNextOutputs(std::span<float> output) noexcept SFFDN_NONBLOCKING;
 
    uint32_t InputChannelCount() const noexcept SFFDN_NONBLOCKING override
    {
        return 1;
    }
 
    uint32_t OutputChannelCount() const noexcept SFFDN_NONBLOCKING override
    {
        return 1;
    }
 
    std::unique_ptr<AudioProcessor> Clone() const override;
 
  private:
    static constexpr std::size_t kLagrangeOrder = 3;
    static constexpr std::size_t kLagrangeTapCount = kLagrangeOrder + 1;
 
    Delay delayline_;
 
    float delay_;
    uint32_t int_delay_;
    float frac_delay_;
    DelayInterpolationType type_;
 
    AllpassFilter allpass_;
 
    std::array<float, kLagrangeTapCount> lagrange_coeffs_{};
    float linear_last_out_;
 
    float next_out_ = 0.f;
    bool has_next_out_ = false;
};
 
} // namespace sfFDN