How to calculate cosmological parameters such as scalar spectrum index and the tensor-to-scalar ratio in constant-roll method?

As we know, the scalar spectrum index and the ratio of tensor-to-scalar in the slow-roll method are obtained with a certain relation according to the parameters of the slow-roll. Now I want to calculate the scalar spectrum index and the tensor-to-scalar ratio in the constant roll method. Does it have a specific formula like the slow-roll section?