1 // Copyright 2009 The Chromium Authors
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 <cstddef>
8 #include <limits>
9 
10 #include "partition_alloc/partition_alloc_base/bits.h"
11 #include "testing/gtest/include/gtest/gtest.h"
12 
13 namespace partition_alloc::internal::base::bits {
14 
TEST(BitsTestPA,Log2Floor)15 TEST(BitsTestPA, Log2Floor) {
16   EXPECT_EQ(-1, Log2Floor(0));
17   EXPECT_EQ(0, Log2Floor(1));
18   EXPECT_EQ(1, Log2Floor(2));
19   EXPECT_EQ(1, Log2Floor(3));
20   EXPECT_EQ(2, Log2Floor(4));
21   for (int i = 3; i < 31; ++i) {
22     unsigned int value = 1U << i;
23     EXPECT_EQ(i, Log2Floor(value));
24     EXPECT_EQ(i, Log2Floor(value + 1));
25     EXPECT_EQ(i, Log2Floor(value + 2));
26     EXPECT_EQ(i - 1, Log2Floor(value - 1));
27     EXPECT_EQ(i - 1, Log2Floor(value - 2));
28   }
29   EXPECT_EQ(31, Log2Floor(0xffffffffU));
30 }
31 
TEST(BitsTestPA,Log2Ceiling)32 TEST(BitsTestPA, Log2Ceiling) {
33   EXPECT_EQ(-1, Log2Ceiling(0));
34   EXPECT_EQ(0, Log2Ceiling(1));
35   EXPECT_EQ(1, Log2Ceiling(2));
36   EXPECT_EQ(2, Log2Ceiling(3));
37   EXPECT_EQ(2, Log2Ceiling(4));
38   for (int i = 3; i < 31; ++i) {
39     unsigned int value = 1U << i;
40     EXPECT_EQ(i, Log2Ceiling(value));
41     EXPECT_EQ(i + 1, Log2Ceiling(value + 1));
42     EXPECT_EQ(i + 1, Log2Ceiling(value + 2));
43     EXPECT_EQ(i, Log2Ceiling(value - 1));
44     EXPECT_EQ(i, Log2Ceiling(value - 2));
45   }
46   EXPECT_EQ(32, Log2Ceiling(0xffffffffU));
47 }
48 
TEST(BitsTestPA,AlignUp)49 TEST(BitsTestPA, AlignUp) {
50   static constexpr size_t kSizeTMax = std::numeric_limits<size_t>::max();
51   EXPECT_EQ(0u, AlignUp(0u, 4u));
52   EXPECT_EQ(4u, AlignUp(1u, 4u));
53   EXPECT_EQ(4096u, AlignUp(1u, 4096u));
54   EXPECT_EQ(4096u, AlignUp(4096u, 4096u));
55   EXPECT_EQ(4096u, AlignUp(4095u, 4096u));
56   EXPECT_EQ(8192u, AlignUp(4097u, 4096u));
57   EXPECT_EQ(kSizeTMax - 31, AlignUp(kSizeTMax - 62, size_t{32}));
58   EXPECT_EQ(kSizeTMax / 2 + 1, AlignUp(size_t{1}, kSizeTMax / 2 + 1));
59 }
60 
TEST(BitsTestPA,AlignUpPointer)61 TEST(BitsTestPA, AlignUpPointer) {
62   static constexpr uintptr_t kUintPtrTMax =
63       std::numeric_limits<uintptr_t>::max();
64   EXPECT_EQ(reinterpret_cast<uint8_t*>(0),
65             AlignUp(reinterpret_cast<uint8_t*>(0), 4));
66   EXPECT_EQ(reinterpret_cast<uint8_t*>(4),
67             AlignUp(reinterpret_cast<uint8_t*>(1), 4));
68   EXPECT_EQ(reinterpret_cast<uint8_t*>(4096),
69             AlignUp(reinterpret_cast<uint8_t*>(1), 4096));
70   EXPECT_EQ(reinterpret_cast<uint8_t*>(4096),
71             AlignUp(reinterpret_cast<uint8_t*>(4096), 4096));
72   EXPECT_EQ(reinterpret_cast<uint8_t*>(4096),
73             AlignUp(reinterpret_cast<uint8_t*>(4095), 4096));
74   EXPECT_EQ(reinterpret_cast<uint8_t*>(8192),
75             AlignUp(reinterpret_cast<uint8_t*>(4097), 4096));
76   EXPECT_EQ(reinterpret_cast<uint8_t*>(kUintPtrTMax - 31),
77             AlignUp(reinterpret_cast<uint8_t*>(kUintPtrTMax - 62), 32));
78   EXPECT_EQ(reinterpret_cast<uint8_t*>(kUintPtrTMax / 2 + 1),
79             AlignUp(reinterpret_cast<uint8_t*>(1), kUintPtrTMax / 2 + 1));
80 }
81 
TEST(BitsTestPA,AlignDown)82 TEST(BitsTestPA, AlignDown) {
83   static constexpr size_t kSizeTMax = std::numeric_limits<size_t>::max();
84   EXPECT_EQ(0u, AlignDown(0u, 4u));
85   EXPECT_EQ(0u, AlignDown(1u, 4u));
86   EXPECT_EQ(0u, AlignDown(1u, 4096u));
87   EXPECT_EQ(4096u, AlignDown(4096u, 4096u));
88   EXPECT_EQ(0u, AlignDown(4095u, 4096u));
89   EXPECT_EQ(4096u, AlignDown(4097u, 4096u));
90   EXPECT_EQ(kSizeTMax - 63, AlignDown(kSizeTMax - 62, size_t{32}));
91   EXPECT_EQ(kSizeTMax - 31, AlignDown(kSizeTMax, size_t{32}));
92   EXPECT_EQ(0ul, AlignDown(size_t{1}, kSizeTMax / 2 + 1));
93 }
94 
TEST(BitsTestPA,AlignDownPointer)95 TEST(BitsTestPA, AlignDownPointer) {
96   static constexpr uintptr_t kUintPtrTMax =
97       std::numeric_limits<uintptr_t>::max();
98   EXPECT_EQ(reinterpret_cast<uint8_t*>(0),
99             AlignDown(reinterpret_cast<uint8_t*>(0), 4));
100   EXPECT_EQ(reinterpret_cast<uint8_t*>(0),
101             AlignDown(reinterpret_cast<uint8_t*>(1), 4));
102   EXPECT_EQ(reinterpret_cast<uint8_t*>(0),
103             AlignDown(reinterpret_cast<uint8_t*>(1), 4096));
104   EXPECT_EQ(reinterpret_cast<uint8_t*>(4096),
105             AlignDown(reinterpret_cast<uint8_t*>(4096), 4096));
106   EXPECT_EQ(reinterpret_cast<uint8_t*>(0),
107             AlignDown(reinterpret_cast<uint8_t*>(4095), 4096));
108   EXPECT_EQ(reinterpret_cast<uint8_t*>(4096),
109             AlignDown(reinterpret_cast<uint8_t*>(4097), 4096));
110   EXPECT_EQ(reinterpret_cast<uint8_t*>(kUintPtrTMax - 63),
111             AlignDown(reinterpret_cast<uint8_t*>(kUintPtrTMax - 62), 32));
112   EXPECT_EQ(reinterpret_cast<uint8_t*>(kUintPtrTMax - 31),
113             AlignDown(reinterpret_cast<uint8_t*>(kUintPtrTMax), 32));
114   EXPECT_EQ(reinterpret_cast<uint8_t*>(0),
115             AlignDown(reinterpret_cast<uint8_t*>(1), kUintPtrTMax / 2 + 1));
116 }
117 
TEST(BitsTestPA,LeftMostBit)118 TEST(BitsTestPA, LeftMostBit) {
119   // Construction of a signed type from an unsigned one of the same width
120   // preserves all bits. Explicitly confirming this behavior here to illustrate
121   // correctness of reusing unsigned literals to test behavior of signed types.
122   // Using signed literals does not work with EXPECT_EQ.
123   static_assert(
124       static_cast<int64_t>(0xFFFFFFFFFFFFFFFFu) == 0xFFFFFFFFFFFFFFFFl,
125       "Comparing signed with unsigned literals compares bits.");
126   static_assert((0xFFFFFFFFFFFFFFFFu ^ 0xFFFFFFFFFFFFFFFFl) == 0,
127                 "Signed and unsigned literals have the same bits set");
128 
129   uint64_t unsigned_long_long_value = 0x8000000000000000u;
130   EXPECT_EQ(LeftmostBit<uint64_t>(), unsigned_long_long_value);
131   EXPECT_EQ(LeftmostBit<int64_t>(), int64_t(unsigned_long_long_value));
132 
133   uint32_t unsigned_long_value = 0x80000000u;
134   EXPECT_EQ(LeftmostBit<uint32_t>(), unsigned_long_value);
135   EXPECT_EQ(LeftmostBit<int32_t>(), int32_t(unsigned_long_value));
136 
137   uint16_t unsigned_short_value = 0x8000u;
138   EXPECT_EQ(LeftmostBit<uint16_t>(), unsigned_short_value);
139   EXPECT_EQ(LeftmostBit<int16_t>(), int16_t(unsigned_short_value));
140 
141   uint8_t unsigned_byte_value = 0x80u;
142   EXPECT_EQ(LeftmostBit<uint8_t>(), unsigned_byte_value);
143   EXPECT_EQ(LeftmostBit<int8_t>(), int8_t(unsigned_byte_value));
144 }
145 
146 }  // namespace partition_alloc::internal::base::bits
147