Stop using parts.

lib/src/utils.dart

+// Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+library crypto.utils;
+
+// Constants.
+const MASK_8 = 0xff;
+const MASK_32 = 0xffffffff;
+const BITS_PER_BYTE = 8;
+const BYTES_PER_WORD = 4;
+
+// Helper methods.
+int add32(x, y) => (x + y) & MASK_32;
+
+int roundUp(val, n) => (val + n - 1) & -n;
+
+// Helper functions used by more than one hasher.
+
+// Rotate left limiting to unsigned 32-bit values.
+int rotl32(int val, int shift) {
+  var mod_shift = shift & 31;
+  return ((val << mod_shift) & MASK_32) |
+      ((val & MASK_32) >> (32 - mod_shift));
+}