def split_v

bend-collections-laws-crypto@1.0.0.0 · proofs/crypto/curve25519/limbs.bend:183

import Base
import bend-collections-laws-crypto@1.0.0.0/spec/lib/common.bend as C

183# a U32 split into its low byte and the rest
184def split_v(+s: U32) -> {Nat.add(v(U32.mod(s, 256)), C.shift(8n, v(U32.div(s, 256)))) == v(s) : Nat}:
185  %Equal.sym(Nat, v(U32.mod(s, 256)), Nat.mod(v(s), 256n), mod256(s)) : {Nat.add(_, C.shift(8n, v(U32.div(s, 256)))) == v(s) : Nat}
186  %Equal.sym(Nat, v(U32.div(s, 256)), Nat.div(v(s), 256n), div256(s)) : {Nat.add(Nat.mod(v(s), 256n), C.shift(8n, _)) == v(s) : Nat}
187  dm256(v(s))