base/bits_unittest.cc

   1 // Copyright (c) 2009 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 // This file contains the unit tests for the bit utilities.
   6
   7 #include "base/bits.h"
   8 #include "testing/gtest/include/gtest/gtest.h"
   9
  10 namespace base {
  11 namespace bits {
  12
  13 TEST(BitsTest, Log2Floor) {
  14   EXPECT_EQ(-1, Log2Floor(0));
  15   EXPECT_EQ(0, Log2Floor(1));
  16   EXPECT_EQ(1, Log2Floor(2));
  17   EXPECT_EQ(1, Log2Floor(3));
  18   EXPECT_EQ(2, Log2Floor(4));
  19   for (int i = 3; i < 31; ++i) {
  20     unsigned int value = 1U << i;
  21     EXPECT_EQ(i, Log2Floor(value));
  22     EXPECT_EQ(i, Log2Floor(value + 1));
  23     EXPECT_EQ(i, Log2Floor(value + 2));
  24     EXPECT_EQ(i - 1, Log2Floor(value - 1));
  25     EXPECT_EQ(i - 1, Log2Floor(value - 2));
  26   }
  27   EXPECT_EQ(31, Log2Floor(0xffffffffU));
  28 }
  29
  30 TEST(BitsTest, Log2Ceiling) {
  31   EXPECT_EQ(-1, Log2Ceiling(0));
  32   EXPECT_EQ(0, Log2Ceiling(1));
  33   EXPECT_EQ(1, Log2Ceiling(2));
  34   EXPECT_EQ(2, Log2Ceiling(3));
  35   EXPECT_EQ(2, Log2Ceiling(4));
  36   for (int i = 3; i < 31; ++i) {
  37     unsigned int value = 1U << i;
  38     EXPECT_EQ(i, Log2Ceiling(value));
  39     EXPECT_EQ(i + 1, Log2Ceiling(value + 1));
  40     EXPECT_EQ(i + 1, Log2Ceiling(value + 2));
  41     EXPECT_EQ(i, Log2Ceiling(value - 1));
  42     EXPECT_EQ(i, Log2Ceiling(value - 2));
  43   }
  44   EXPECT_EQ(32, Log2Ceiling(0xffffffffU));
  45 }
  46
  47 }  // namespace bits
  48 }  // namespace base