Function fixed_base 

pub fn fixed_base() -> Program

Fixed-base scalar multiplication. Outputs projective X, Y, Z (indices 0..3).

[s]B = sum_i d_i T_i with T_i = 2^offset(i) B, split into two sums by position in LOOKUP_ORDER: digits at even positions form one chain and digits at odd positions the other. The two chains are independent and interleaved, so the scheduler can fill the bundle slots that one chain’s add/multiply recurrence would leave empty; one final addition joins them.