part_modifiers.hpp

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#pragma once
 
namespace ts {

struct PartModifiers {
    int vibrato_rate = neutral;
    int vibrato_depth = neutral;
    int vibrato_delay = neutral;
    int tvf_cutoff = neutral;
    int env_attack = neutral;
    int env_decay = neutral;
    int env_release = neutral;
 
    // TVF resonance (CC#71 / NRPN `01 21` / `40 1x 33`) is deliberately absent.
    //
    // It is not unimplemented here — it is unimplemented in the engine. The byte it writes,
    // `part+0x3e7`, is written by the CC handler, the NRPN handler, the SysEx handler and the reset
    // path, it can be read back over a dump, and **no code anywhere reads it**. Its patch-level
    // sibling `part+0x456` *is* wired into the resonance path, so this is a route that was left
    // unconnected rather than a parameter the module has no use for. `Part::tvf_resonance` stays
    // write-only on purpose; adding it here would make this engine louder than the one it copies.

    static constexpr int neutral = 0x40;

    [[nodiscard]] constexpr bool is_neutral() const noexcept
    {
        return vibrato_rate == neutral && vibrato_depth == neutral && vibrato_delay == neutral
               && tvf_cutoff == neutral && env_attack == neutral && env_decay == neutral
               && env_release == neutral;
    }

    [[nodiscard]] constexpr int attack_bias() const noexcept { return (env_attack - neutral) * 2; }

    [[nodiscard]] constexpr int decay_bias() const noexcept { return (env_decay - neutral) * 2; }

    [[nodiscard]] constexpr int release_bias() const noexcept
    {
        return (env_release - neutral) * 2;
    }

    [[nodiscard]] constexpr int cutoff_offset() const noexcept
    {
        return (tvf_cutoff - neutral) * 0x100;
    }
};
 
} // namespace ts