def Mag.dec

bend-kit-bignum@0.1.0.0 · bigint.bend:78

import Base

78# a - w for the borrow w; z says w is 0. Leaves zero limbs on top.
79def Mag.dec(a: List<&2, U32>, z: Bool, +w: U32) -> List<&2, U32>:
80  match a z:
81    case s True{}:
82      s
83    case Nil{} False{}:
84      Nil{}
85    case Con{x, xs} False{}:
86      +t = (x + 10000 - w : U32)
87      +k = (1 - t / 10000 : U32)
88      Con{(t % 10000 : U32), Mag.dec(xs, U32.is_zero(k), k)}