Limbs.carry_cb: def of bend-collections-laws-crypto@1.0.0.0
Import: import bend-collections-laws-crypto@1.0.0.0/proofs/crypto/curve25519/limbs.bend as Limbs
Lines 281-293 of bend-collections-laws-crypto@1.0.0.0/proofs/crypto/curve25519/limbs.bend: https://jend.leeeet.dev/read.txt?path=bend-collections-laws-crypto@1.0.0.0/proofs/crypto/curve25519/limbs.bend&start_line=281&end_line=293

import Base
import bend-collections-laws-crypto@1.0.0.0/src/crypto/curve25519/field.bend as F
import bend-collections-laws-crypto@1.0.0.0/proofs/lib/word.bend as WD

# the carry out is at most 2^21
def carry_cb(+one: Nat, +h1: {one == 1n : Nat}, +xs: List<&2, U32>, +c: U32, +hx: {lea(xs, WD.sc(28n, one)) == True{} : Bool}, +hc: {Nat.is_le(v(c), WD.sc(21n, one)) == True{} : Bool}) -> {Nat.is_le(v(cc(F.carry(xs, c))), WD.sc(21n, one)) == True{} : Bool}:
  match xs:
    case Nil{}:
      hc
    case Con{+h, +t}:
      +hh = lea_head(h, t, WD.sc(28n, one), hx)
      +ht = lea_tail(h, t, WD.sc(28n, one), hx)
      +s = U32.add(h, c)
      +lo = U32.mod(s, 256)
      +r = F.carry(t, U32.div(s, 256))
      %Equal.sym(U32, cc(F.carry_con(lo, r)), cc(r), cc_con(lo, r)) : {Nat.is_le(v(_), WD.sc(21n, one)) == True{} : Bool}
      carry_cb(one, h1, t, U32.div(s, 256), ht, c_next(one, h1, h, c, hh, hc))

Uses (19):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Bool
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Equal.sym
  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.is_le
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32.add
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32.div
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32.mod
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-crypto@1.0.0.0/proofs/crypto/curve25519/limbs.bend&name=c_next
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-crypto@1.0.0.0/proofs/crypto/curve25519/limbs.bend&name=cc
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-crypto@1.0.0.0/proofs/crypto/curve25519/limbs.bend&name=cc_con
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-crypto@1.0.0.0/proofs/crypto/curve25519/limbs.bend&name=lea
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-crypto@1.0.0.0/proofs/crypto/curve25519/limbs.bend&name=lea_head
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-crypto@1.0.0.0/proofs/crypto/curve25519/limbs.bend&name=lea_tail
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-crypto@1.0.0.0/proofs/crypto/curve25519/limbs.bend&name=v
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-crypto@1.0.0.0/proofs/lib/word.bend&name=sc
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-crypto@1.0.0.0/src/crypto/curve25519/field.bend&name=carry
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-crypto@1.0.0.0/src/crypto/curve25519/field.bend&name=carry_con