Ecdsa.finish: def of bend-collections@1.0.0.0
Import: import bend-collections@1.0.0.0/src/crypto/secp256k1/ecdsa.bend as Ecdsa
Lines 84-93 of bend-collections@1.0.0.0/src/crypto/secp256k1/ecdsa.bend: https://jend.leeeet.dev/read.txt?path=bend-collections@1.0.0.0/src/crypto/secp256k1/ecdsa.bend&start_line=84&end_line=93

import Base
import bend-collections@1.0.0.0/src/crypto/secp256k1/field.bend as F
import bend-collections@1.0.0.0/src/crypto/secp256k1/scalar.bend as S
import bend-collections@1.0.0.0/src/crypto/secp256k1/bytes.bend as B

# r = x(R) mod n, s = k^-1 (z + r d) mod n, made low (s > n / 2 is replaced
# by n - s, which flips the parity bit of the recovery id); the recovery
# id is the parity of y(R), plus 2 when x(R) >= n
def finish(+z: List<&2, Nat>, +d: List<&2, Nat>, +k: List<&2, Nat>, +x: List<&2, Nat>, +y: List<&2, Nat>) -> Attempt:
  +r = S.reduce(x)
  +s0 = S.mul(S.inv(k), S.add(z, S.mul(r, d)))
  +high = b2n(S.is_high(s0))
  +par = F.parity(y)
  +id = Nat.add(Nat.mul(b2n(Bool.not(S.lt_n(x))), 2n), Nat.sub(Nat.add(par, high), Nat.mul(Nat.mul(par, high), 2n)))
  finish_if(Bool.or(S.is_zero(r), S.is_zero(s0)), Signature{B.to_be(r), B.to_be(S.select(high, S.neg(s0), s0)), U32.from_nat(id)})

Uses (23):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Bool.not
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Bool.or
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=List
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat.add
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat.mul
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat.sub
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32.from_nat
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/crypto/secp256k1/bytes.bend&name=to_be
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/crypto/secp256k1/ecdsa.bend&name=Attempt
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/crypto/secp256k1/ecdsa.bend&name=Signature
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/crypto/secp256k1/ecdsa.bend&name=b2n
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/crypto/secp256k1/ecdsa.bend&name=finish_if
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/crypto/secp256k1/field.bend&name=parity
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/crypto/secp256k1/scalar.bend&name=add
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/crypto/secp256k1/scalar.bend&name=inv
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/crypto/secp256k1/scalar.bend&name=is_high
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/crypto/secp256k1/scalar.bend&name=is_zero
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/crypto/secp256k1/scalar.bend&name=lt_n
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/crypto/secp256k1/scalar.bend&name=mul
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/crypto/secp256k1/scalar.bend&name=neg
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/crypto/secp256k1/scalar.bend&name=reduce
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/crypto/secp256k1/scalar.bend&name=select