duck

public class Oscillator {

    float min;
    float max;
    float value;
    float velocity;
    float speed;
    float target;

    public Oscillator(float min, float max, float speed) {
        this.min = min;
        this.max = max;
        this.speed = speed;
        target = (min+max) * 0.5f;
        value = min;
    }

    public float GetNext() {
        velocity += (value < target ? 1 : -1) * speed;
        value += velocity;
        return value;
    }

}