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
   9 #include <limits>
  10
  11 #include "testing/gtest/include/gtest/gtest.h"
  12
  13 namespace base {
  14 namespace bits {
  15
  16 TEST(BitsTest, Log2Floor) {
  17   EXPECT_EQ(-1, Log2Floor(0));
  18   EXPECT_EQ(0, Log2Floor(1));
  19   EXPECT_EQ(1, Log2Floor(2));
  20   EXPECT_EQ(1, Log2Floor(3));
  21   EXPECT_EQ(2, Log2Floor(4));
  22   for (int i = 3; i < 31; ++i) {
  23     unsigned int value = 1U << i;
  24     EXPECT_EQ(i, Log2Floor(value));
  25     EXPECT_EQ(i, Log2Floor(value + 1));
  26     EXPECT_EQ(i, Log2Floor(value + 2));
  27     EXPECT_EQ(i - 1, Log2Floor(value - 1));
  28     EXPECT_EQ(i - 1, Log2Floor(value - 2));
  29   }
  30   EXPECT_EQ(31, Log2Floor(0xffffffffU));
  31 }
  32
  33 TEST(BitsTest, Log2Ceiling) {
  34   EXPECT_EQ(-1, Log2Ceiling(0));
  35   EXPECT_EQ(0, Log2Ceiling(1));
  36   EXPECT_EQ(1, Log2Ceiling(2));
  37   EXPECT_EQ(2, Log2Ceiling(3));
  38   EXPECT_EQ(2, Log2Ceiling(4));
  39   for (int i = 3; i < 31; ++i) {
  40     unsigned int value = 1U << i;
  41     EXPECT_EQ(i, Log2Ceiling(value));
  42     EXPECT_EQ(i + 1, Log2Ceiling(value + 1));
  43     EXPECT_EQ(i + 1, Log2Ceiling(value + 2));
  44     EXPECT_EQ(i, Log2Ceiling(value - 1));
  45     EXPECT_EQ(i, Log2Ceiling(value - 2));
  46   }
  47   EXPECT_EQ(32, Log2Ceiling(0xffffffffU));
  48 }
  49
  50 TEST(BitsTest, Align) {
  51   const size_t kSizeTMax = std::numeric_limits<size_t>::max();
  52   EXPECT_EQ(0ul, Align(0, 4));
  53   EXPECT_EQ(4ul, Align(1, 4));
  54   EXPECT_EQ(4096ul, Align(1, 4096));
  55   EXPECT_EQ(4096ul, Align(4096, 4096));
  56   EXPECT_EQ(4096ul, Align(4095, 4096));
  57   EXPECT_EQ(8192ul, Align(4097, 4096));
  58   EXPECT_EQ(kSizeTMax - 31, Align(kSizeTMax - 62, 32));
  59   EXPECT_EQ(kSizeTMax / 2 + 1, Align(1, kSizeTMax / 2 + 1));
  60 }
  61
  62 }  // namespace bits
  63 }  // namespace base