def dec_root

bend-collections@1.0.0.0 · src/crypto/ed25519/point.bend:144

import Base
import bend-collections@1.0.0.0/src/crypto/curve25519/field.bend as F

144def dec_root(+c: Cs, +x: List<&2, U32>, +y: List<&2, U32>, +x0: U32, +u: List<&2, U32>, +vxx: List<&2, U32>, is_u: Bool, is_nu: Bool) -> Maybe<&2, Pt>:
145  match is_u:
146    case True{}:
147      dec_fin(x, y, x0, Bool.and(F.is_zero(x), U32.is_eq(x0, 1)))
148    case False{}:
149      match is_nu:
150        case True{}:
151          +x1 = F.mul(x, cs_s(c))
152          dec_fin(x1, y, x0, Bool.and(F.is_zero(x1), U32.is_eq(x0, 1)))
153        case False{}:
154          None{}