def negative_pack

bend-collections-laws-math@1.0.0.0 · proofs/math/u64/u64.bend:94

import Base
import bend-collections-laws-math@1.0.0.0/src/math/u64.bend as U
import bend-collections-laws-math@1.0.0.0/proofs/lib/lemmas/src/wide.bend as W
import bend-collections-laws-math@1.0.0.0/proofs/lib/lemmas/spec/numeric.bend as S

94# The sign of the 64-bit word is the top bit of the high limb.
95def negative_pack(+lo: U32, +hi: U32) -> {S.negative(W.pack(lo, hi)) == U32.is_ge(hi, 2147483648) : Bool}:
96  match lo hi:
97    case U32{a} U32{b}:
98      %Equal.sym(Word(64n), W.join(32n, 32n, Word.zero(32n), S.sign_threshold(31n)), S.sign_threshold(63n), threshold()) : {Cmp.is_ge(Word.cmp(64n, W.join(32n, 32n, a, b), _)) == U32.is_ge(U32{b}, 2147483648) : Bool}
99      %Equal.sym(Cmp, Word.cmp(64n, W.join(32n, 32n, a, b), W.join(32n, 32n, Word.zero(32n), S.sign_threshold(31n))), U.order(Word.cmp(32n, b, S.sign_threshold(31n)), Word.cmp(32n, a, Word.zero(32n))), cmp_join(32n, 32n, a, b, Word.zero(32n), S.sign_threshold(31n))) : {Cmp.is_ge(_) == U32.is_ge(U32{b}, 2147483648) : Bool}
100      %Equal.sym(U32, U32{S.sign_threshold(31n)}, 2147483648, threshold_u32()) : {Cmp.is_ge(U.order(Word.cmp(32n, b, S.sign_threshold(31n)), Word.cmp(32n, a, Word.zero(32n)))) == U32.is_ge(U32{b}, _) : Bool}
101      ge_order(Word.cmp(32n, b, S.sign_threshold(31n)), Word.cmp(32n, a, Word.zero(32n)), ge_zero(32n, a))