def subval

bend-collections-laws-math@1.0.0.0 · proofs/math/typed/w64add.bend:307

import Base
import bend-collections-laws-math@1.0.0.0/spec/lib/common.bend as C
import bend-collections-laws-math@1.0.0.0/spec/math/w64.bend as SW
import bend-collections-laws-math@1.0.0.0/src/math/w64.bend as X
import bend-collections-laws-math@1.0.0.0/src/math/u64.bend as WU
import bend-collections-laws-math@1.0.0.0/proofs/lib/nat.bend as N
import bend-collections-laws-math@1.0.0.0/proofs/lib/lemmas/proofs/nat_algebra.bend as NA
import bend-collections-laws-math@1.0.0.0/proofs/lib/word.bend as WD
import bend-collections-laws-math@1.0.0.0/proofs/lib/lemmas/spec/numeric.bend as S
import bend-collections-laws-math@1.0.0.0/proofs/math/typed/w64mul.bend as W64M
import bend-collections-laws-math@1.0.0.0/proofs/math/typed/width.bend as WW
import bend-collections-laws-math@1.0.0.0/proofs/math/natural/arith.bend as NR

307def subval(+one: Nat, +h1: {one == 1n : Nat}, +al: U32, +ah: U32, +bl: U32, +bh: U32, +hle: {Nat.is_le(val(bl, bh), val(al, ah)) == True{} : Bool}) -> {SW.value(X.sub(WU.U64{al, ah}, WU.U64{bl, bh})) == Nat.sub(val(al, ah), val(bl, bh)) : Nat}:
308  +lo = U32.sub(al, bl)
309  +c1 = U32.is_lt(al, bl)
310  +s = U32.sub(ah, bh)
311  +cb = X.b32(c1)
312  +hi = U32.sub(s, cb)
313  +b1 = WD.bo(c1, one)
314  +b2 = WD.bo(U32.is_lt(ah, bh), one)
315  +b3 = WD.bo(U32.is_lt(s, cb), one)
316  +ecb = Equal.trans(Nat, v(cb), S.bit_value(c1), b1, W64M.b32_v(c1), Equal.sym(Nat, b1, S.bit_value(c1), WD.bo_bit(c1, one, h1)))
317  +e3 = Equal.trans(Nat, Nat.add(v(hi), b1), Nat.add(v(hi), v(cb)), Nat.add(v(s), C.shift(32n, b3)), Equal.cong(Nat, Nat, t => Nat.add(v(hi), t), b1, v(cb), Equal.sym(Nat, v(cb), b1, ecb)), sub_cons(one, h1, s, cb))
318  +eq = sub_alg(v(lo), v(hi), v(al), v(ah), v(bl), v(bh), v(s), b1, b2, b3, sub_cons(one, h1, al, bl), sub_cons(one, h1, ah, bh), e3)
319  +q = Nat.add(b2, b3)
320  +va = val(al, ah)
321  +vbb = val(bl, bh)
322  +vs = val(lo, hi)
323  +T = C.shift(64n, q)
324  +eq2 = Equal.trans(Nat, Nat.add(vs, vbb), Nat.add(va, C.shift(32n, C.shift(32n, q))), Nat.add(va, T), eq, Equal.cong(Nat, Nat, t => Nat.add(va, t), C.shift(32n, C.shift(32n, q)), T, Equal.sym(Nat, T, C.shift(32n, C.shift(32n, q)), WW.shift_comp(32n, 32n, q))))
325  +dd = Nat.sub(va, vbb)
326  +ea = Equal.sym(Nat, Nat.add(vbb, dd), va, N.sub_add(va, vbb, hle))
327  +e4 = Equal.trans(Nat, Nat.add(vbb, vs), Nat.add(vs, vbb), Nat.add(vbb, Nat.add(dd, T)), N.add_comm(vbb, vs), Equal.trans(Nat, Nat.add(vs, vbb), Nat.add(va, T), Nat.add(vbb, Nat.add(dd, T)), eq2, Equal.trans(Nat, Nat.add(va, T), Nat.add(Nat.add(vbb, dd), T), Nat.add(vbb, Nat.add(dd, T)), Equal.cong(Nat, Nat, t => Nat.add(t, T), va, Nat.add(vbb, dd), ea), NA.add_assoc(vbb, dd, T))))
328  +e5 = NR.add_cancel(vbb, vs, Nat.add(dd, T), e4)
329  +hf = WW.limbs_fit(32n, 32n, v(lo), v(hi), vb(lo), vb(hi))
330  sub_fin(vs, dd, q, e5, hf, Nat.is_eq(q, 0n), {==})