1 /*
   2  * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "utilities/count_trailing_zeros.hpp"
  27 #include "utilities/globalDefinitions.hpp"
  28 #include "unittest.hpp"
  29 
  30 TEST(count_trailing_zeros, one_or_two_set_bits) {
  31   unsigned i = 0;               // Position of a set bit.
  32   for (uintx ix = 1; ix != 0; ix <<= 1, ++i) {
  33     unsigned j = 0;             // Position of a set bit.
  34     for (uintx jx = 1; jx != 0; jx <<= 1, ++j) {
  35       uintx value = ix | jx;
  36       EXPECT_EQ(MIN2(i, j), count_trailing_zeros(value))
  37         << "value = " << value;
  38     }
  39   }
  40 }
  41 
  42 TEST(count_trailing_zeros, all_ones_followed_by_all_zeros) {
  43   unsigned i = BitsPerWord - 1; // Index of most significant set bit.
  44   uintx value = ~(uintx)0;
  45   for ( ; value != 0; value >>= 1, --i) {
  46     EXPECT_EQ(0u, count_trailing_zeros(value))
  47       << "value = " << value;
  48   }
  49 }
  50 
  51 TEST(count_trailing_zeros, all_zeros_followed_by_all_ones) {
  52   unsigned i = 0;               // Index of least significant set bit.
  53   uintx value = ~(uintx)0;
  54   for ( ; value != 0; value <<= 1, ++i) {
  55     EXPECT_EQ(i, count_trailing_zeros(value))
  56       << "value = " << value;
  57   }
  58 }