# effects module

## Owned files

- Related rack implementation: `../FXProcessor.h`, `../FXProcessor.cpp`
- Biquad.h
- Hyper.h, Hyper.cpp
- Chorus.h, Chorus.cpp
- Flanger.h, Flanger.cpp
- Phaser.h, Phaser.cpp
- Distortion.h, Distortion.cpp
- EQ.h, EQ.cpp
- Compressor.h, Compressor.cpp
- Delay.h, Delay.cpp
- Reverb.h, Reverb.cpp

## Rules

- Implement the `FXUnit` interface with `prepare`, `reset` and `process (float* l, float* r, int numSamples, const float p[4])`.
- Process full-wet in place; FXProcessor handles the dry/wet mix.
- Document what p[0] through p[3] mean for each unit in the header comment.
- Use `std::vector<float>` for delay lines and size them in `prepare()`.
- Use `juce::MathConstants<T>::pi` and `twoPi` in delay LFOs, not raw literals.
- Never allocate or resize a delay line inside `process`.
- Guard empty delay lines with an early `if (len < 4) return;`.

## IF-THEN

- IF a unit needs a delay line THEN allocate it in `prepare()` at the full required length and only read and write it in `process`.
- Include the existing rack interface via `../FXProcessor.h`; no source relocation is implied by this guidance.

## Examples

```cpp
// BAD: reallocates a delay line on the audio thread
void process (float* l, float* r, int n, const float p[4]) override
{
    std::vector<float> delay ((size_t) (sr * 0.05), 0.0f);
    ...
}
```

```cpp
// GOOD: sized once at prepare time, reused per block
void prepare (double sampleRate, int) override
{
    sr = sampleRate;
    delayL.assign ((size_t) (sr * 0.05), 0.0f);
    delayR.assign ((size_t) (sr * 0.05), 0.0f);
}
```

This file overrides /AGENT.md where they conflict.