def csub

bend-collections-laws-crypto@1.0.0.0 · src/crypto/curve25519/field.bend:261

import Base

261# x - p when x >= p, else x (x tight): x + 2^256 - p carries out iff x >= p
262def csub(+x: List<&2, U32>) -> List<&2, U32>:
263  csub_fin(carry(addl(x, comp_p()), 0), x)