envelope_machine.hpp

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#pragma once
 
#include "tabulasonora/partial_parameters.hpp"
#include "tabulasonora/table_set.hpp"
 
#include <array>
#include <cstdint>
#include <limits>
 
namespace ts {

class EnvelopeMachine {
public:
    static constexpr int unity_multiplier = 0x100;

    static constexpr int minimum_segment_ticks = 9;

    static constexpr std::int64_t hold_forever = std::numeric_limits<std::int64_t>::max();

    explicit EnvelopeMachine(const TableSet& tables);

    [[nodiscard]] static constexpr bool is_linear_segment(int rate_byte) noexcept
    {
        return (rate_byte & 0x80) != 0;
    }

    [[nodiscard]] int rate_scale(int base_rate, int modifier) const noexcept;

    [[nodiscard]] int level_scale(int level, int modifier) const noexcept;

    [[nodiscard]] double segment_milliseconds(int rate_byte,
                                              int rate_multiplier,
                                              int velocity_multiplier = unity_multiplier,
                                              int bias = 0) const noexcept;

    [[nodiscard]] double
    segment_curve(double position, double start, double target, bool linear) const noexcept;

    [[nodiscard]] std::int64_t hold_samples(const PartialParameters& partial,
                                            int velocity) const noexcept;
 
private:
    std::span<const std::uint16_t> rate_curve_;
    std::span<const std::uint16_t> rate_out_;
    std::span<const std::uint8_t> scale_curve_;

    std::array<double, 257> shape_{};
};
 
} // namespace ts