viable revisit v1

Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>

src/sat/smt/polysat/number.h

@@ -0,0 +1,30 @@
+/*++
+Copyright (c) 2021 Microsoft Corporation
+
+Module Name:
+
+    polysat numbers
+
+Author:
+
+    Nikolaj Bjorner (nbjorner) 2021-03-19
+    Jakob Rath 2021-04-06
+
+--*/
+#pragma once
+#include "sat/smt/polysat/types.h"
+
+namespace polysat {
+
+    inline unsigned get_parity(rational const& val, unsigned num_bits) {
+        if (val.is_zero())
+            return num_bits;
+        return val.trailing_zeros();
+    };
+
+    /** Return val with the lower k bits set to zero. */
+    inline rational clear_lower_bits(rational const& val, unsigned k) {
+        return val - mod(val, rational::power_of_two(k));
+    }
+
+}