finish uncarry

projects/lib/GmpAux.v

@@ -27,6 +27,12 @@ Lemma Z_mod_add_carry: forall (a b m: Z),
    a + b = (a + b) mod m + m.
 Proof. Admitted.
 
+Lemma Z_mod_add_uncarry: forall (a b m: Z),
+  m > 0 -> 0 <= a < m -> 0 <= b < m ->
+  (a + b) mod m >= b ->
+  a + b = (a + b) mod m.
+Proof. Admitted.
+
 Lemma Z_of_nat_succ: forall (n: nat),
   Z.of_nat (S n) = Z.of_nat n + 1.
 Proof. lia. Qed.

projects/lib/gmp_proof_manual.v

@@ -548,7 +548,119 @@ Qed.
 Lemma proof_of_mpn_add_1_entail_wit_3_2 : mpn_add_1_entail_wit_3_2.
 Proof.
   pre_process.
-Admitted. 
+  rewrite replace_Znth_app_r.
+  - Exists l'''.
+    rewrite H14.
+    assert (i - i = 0) by lia.
+    rewrite H26.
+    set (new_b := (unsigned_last_nbits (Znth i l_3 0 + b) 32)).
+    rewrite replace_Znth_nothing; try lia.
+    assert (replace_Znth 0 new_b (a :: nil) = new_b :: nil). {
+      unfold replace_Znth.
+      unfold Z.to_nat.
+      unfold replace_nth.
+      reflexivity.
+    }
+    rewrite H27.
+    Exists (l'_2 ++ new_b :: nil).
+    Exists (val2_2 + new_b * (UINT_MOD^ i)).
+    Exists (val1_2 + (Znth i l_3 0) * (UINT_MOD^ i)).
+    Exists l_3.
+    entailer!.
+    + rewrite Zlength_app.
+      rewrite H14.
+      unfold Zlength.
+      unfold Zlength_aux.
+      lia.
+    + assert (val1_2 + Znth i l_3 0 * 4294967296 ^ i + b_pre = (val1_2 + b_pre) + Znth i l_3 0 * 4294967296 ^ i) by lia.
+      rewrite H28.
+      rewrite <- H13.
+      assert (Znth i l_3 0 + b = new_b).
+      {
+        subst new_b.
+        unfold unsigned_last_nbits.
+        unfold unsigned_last_nbits in H3.
+        assert (2^32 = 4294967296). { nia. }
+        rewrite H29 in *.
+        assert (0 <= Znth i l_3 0 < 4294967296). {
+          assert (l_2=l_3).
+          {
+            pose proof (list_store_Z_compact_reverse_injection l_2 l_3 val val).
+            apply H30 in H9; try tauto.
+          }
+          assert (i < Zlength l_3). {
+            subst l_3.
+            rewrite H17.
+            tauto.
+          }
+          unfold list_store_Z_compact in H9.
+          apply list_within_bound_Znth.
+          lia.
+          tauto.
+        }
+        apply Z_mod_add_uncarry; try lia; try tauto.
+      }
+      assert (b * 4294967296 ^ i + Znth i l_3 0 * 4294967296 ^ i = new_b * 4294967296 ^ i + 0 * 4294967296 ^ (i + 1)).
+      {
+        subst new_b.
+        Search [ Zmult Zplus "distr" ].
+        rewrite <- Z.mul_add_distr_r.
+        rewrite (Zpow_add_1 4294967296 i); try lia.
+      }
+      lia.
+    + pose proof (__list_store_Z_concat_r l'_2 val2_2 new_b).
+      apply H28 in H12.
+      rewrite H14 in H12.
+      assert (new_b * 4294967296 ^ i + val2_2 = (val2_2 + new_b * 4294967296 ^ i)) by lia.
+      rewrite H29 in H12.
+      tauto.
+      subst new_b.
+      unfold unsigned_last_nbits.
+      assert (2 ^ 32 = 4294967296). { nia. }
+      rewrite H29.
+      apply Z.mod_pos_bound.
+      lia.
+      + assert (l_2=l_3).
+        {
+          pose proof (list_store_Z_compact_reverse_injection l_2 l_3 val val).
+          apply H28 in H9; try tauto.
+        }
+
+        assert (i < Zlength l_3). {
+          subst l_3.
+          rewrite H17.
+          tauto.
+        }
+
+        assert((sublist 0 (i + 1) l_3) = (sublist 0 i l_3) ++ (Znth i l_3 0)  :: nil). {
+          pose proof (sublist_split 0 (i+1) i l_3).
+          pose proof (sublist_single i l_3 0).
+          rewrite <-H31.
+          apply H30.
+          lia.
+          subst l_3.
+          rewrite Zlength_correct in H29.
+          lia.
+          rewrite Zlength_correct in H29.
+          lia.
+        }
+        rewrite H30.
+        pose proof (__list_store_Z_concat_r (sublist 0 i l_3) val1_2 (Znth i l_3 0)).
+        apply H31 in H11.
+        rewrite Zlength_sublist0 in H11.
+        assert (val1_2 + Znth i l_3 0 * 4294967296 ^ i = Znth i l_3 0 * 4294967296 ^ i + val1_2) by lia.
+        rewrite H32.
+        tauto.
+        subst l_3.
+        rewrite H17.
+        lia.
+        apply list_within_bound_Znth.
+        lia.
+        unfold list_store_Z_compact in H9.
+        tauto.
+  - pose proof (Zlength_sublist0 i l'_2).
+    lia.
+Qed.
 
 Lemma proof_of_mpn_add_1_return_wit_1 : mpn_add_1_return_wit_1.
 Proof.