def prev_index

bend-collections-laws-crypto@1.0.0.0 · spec/crypto/argon2/argon2.bend:295

import Base

295# The previous block: B[l][j - 1], or B[l][q - 1] for j = 0.
296def prev_index(+l: Nat, +q: Nat, +j: Nat, first: Bool) -> Nat:
297  match first:
298    case True{}:
299      Nat.add(Nat.mul(l, q), Nat.sub(q, 1n))
300    case False{}:
301      Nat.sub(Nat.add(Nat.mul(l, q), j), 1n)