1// Copyright (c) 2012 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#include "media/base/bit_reader.h"
6
7#include "testing/gtest/include/gtest/gtest.h"
8
9namespace media {
10
11static void SetBit(uint8* buf, size_t size, size_t bit_pos) {
12  size_t byte_pos = bit_pos / 8;
13  bit_pos -= byte_pos * 8;
14  DCHECK_LT(byte_pos, size);
15  buf[byte_pos] |= (1 << (7 - bit_pos));
16}
17
18TEST(BitReaderTest, NormalOperationTest) {
19  uint8 value8;
20  uint64 value64;
21  // 0101 0101 1001 1001 repeats 4 times
22  uint8 buffer[] = {0x55, 0x99, 0x55, 0x99, 0x55, 0x99, 0x55, 0x99};
23  BitReader reader1(buffer, 6);  // Initialize with 6 bytes only
24
25  EXPECT_TRUE(reader1.ReadBits(1, &value8));
26  EXPECT_EQ(value8, 0);
27  EXPECT_TRUE(reader1.ReadBits(8, &value8));
28  EXPECT_EQ(value8, 0xab);  // 1010 1011
29  EXPECT_TRUE(reader1.ReadBits(7, &value64));
30  EXPECT_TRUE(reader1.ReadBits(32, &value64));
31  EXPECT_EQ(value64, 0x55995599u);
32  EXPECT_FALSE(reader1.ReadBits(1, &value8));
33  value8 = 0xff;
34  EXPECT_TRUE(reader1.ReadBits(0, &value8));
35  EXPECT_EQ(value8, 0);
36
37  BitReader reader2(buffer, 8);
38  EXPECT_TRUE(reader2.ReadBits(64, &value64));
39  EXPECT_EQ(value64, 0x5599559955995599ull);
40  EXPECT_FALSE(reader2.ReadBits(1, &value8));
41  EXPECT_TRUE(reader2.ReadBits(0, &value8));
42}
43
44TEST(BitReaderTest, ReadBeyondEndTest) {
45  uint8 value8;
46  uint8 buffer[] = {0x12};
47  BitReader reader1(buffer, sizeof(buffer));
48
49  EXPECT_TRUE(reader1.ReadBits(4, &value8));
50  EXPECT_FALSE(reader1.ReadBits(5, &value8));
51  EXPECT_FALSE(reader1.ReadBits(1, &value8));
52  EXPECT_TRUE(reader1.ReadBits(0, &value8));
53}
54
55TEST(BitReaderTest, SkipBitsTest) {
56  uint8 value8;
57  uint8 buffer[] = { 0x0a, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 };
58  BitReader reader1(buffer, sizeof(buffer));
59
60  EXPECT_TRUE(reader1.SkipBits(2));
61  EXPECT_TRUE(reader1.ReadBits(3, &value8));
62  EXPECT_EQ(value8, 1);
63  EXPECT_TRUE(reader1.SkipBits(11));
64  EXPECT_TRUE(reader1.ReadBits(8, &value8));
65  EXPECT_EQ(value8, 3);
66  EXPECT_TRUE(reader1.SkipBits(76));
67  EXPECT_TRUE(reader1.ReadBits(4, &value8));
68  EXPECT_EQ(value8, 13);
69  EXPECT_FALSE(reader1.SkipBits(100));
70  EXPECT_TRUE(reader1.SkipBits(0));
71  EXPECT_FALSE(reader1.SkipBits(1));
72}
73
74TEST(BitReaderTest, VariableSkipBitsTest) {
75  uint8 buffer[256] = {0};
76
77  // The test alternates between ReadBits and SkipBits.
78  // The first number is the number of bits to read, the second one is the
79  // number of bits to skip. The number of bits to read was arbitrarily chosen
80  // while the number of bits to skip was chosen so as to cover from small skips
81  // to large skips.
82  const size_t pattern_read_skip[][2] = {
83    {  5,  17 },
84    {  4,  34 },
85    {  0,  44 },
86    {  3,   4 },   // Note: aligned read.
87    {  7,   7 },   // Note: both read&skip cross byte boundary.
88    { 17,  68 },
89    {  7, 102 },
90    {  9, 204 },
91    {  3, 408 } };
92
93  // Set bits to one only for the first and last bit of each read
94  // in the pattern.
95  size_t pos = 0;
96  for (size_t k = 0; k < arraysize(pattern_read_skip); ++k) {
97    const size_t read_bit_count = pattern_read_skip[k][0];
98    if (read_bit_count > 0) {
99      SetBit(buffer, sizeof(buffer), pos);
100      SetBit(buffer, sizeof(buffer), pos + read_bit_count - 1);
101      pos += read_bit_count;
102    }
103    pos += pattern_read_skip[k][1];
104  }
105
106  // Run the test.
107  BitReader bit_reader(buffer, sizeof(buffer));
108  EXPECT_EQ(bit_reader.bits_available(), static_cast<int>(sizeof(buffer) * 8));
109  for (size_t k = 0; k < arraysize(pattern_read_skip); ++k) {
110    const size_t read_bit_count = pattern_read_skip[k][0];
111    if (read_bit_count > 0) {
112      int value;
113      EXPECT_TRUE(bit_reader.ReadBits(read_bit_count, &value));
114      EXPECT_EQ(value, 1 | (1 << (read_bit_count - 1)));
115    }
116    EXPECT_TRUE(bit_reader.SkipBits(pattern_read_skip[k][1]));
117  }
118}
119
120TEST(BitReaderTest, BitsReadTest) {
121  int value;
122  bool flag;
123  uint8 buffer[] = { 0x0a, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 };
124  BitReader reader1(buffer, sizeof(buffer));
125  EXPECT_EQ(reader1.bits_available(), 120);
126
127  EXPECT_TRUE(reader1.SkipBits(2));
128  EXPECT_EQ(reader1.bits_read(), 2);
129  EXPECT_EQ(reader1.bits_available(), 118);
130  EXPECT_TRUE(reader1.ReadBits(3, &value));
131  EXPECT_EQ(reader1.bits_read(), 5);
132  EXPECT_EQ(reader1.bits_available(), 115);
133  EXPECT_TRUE(reader1.ReadFlag(&flag));
134  EXPECT_EQ(reader1.bits_read(), 6);
135  EXPECT_EQ(reader1.bits_available(), 114);
136  EXPECT_TRUE(reader1.SkipBits(76));
137  EXPECT_EQ(reader1.bits_read(), 82);
138  EXPECT_EQ(reader1.bits_available(), 38);
139}
140
141}  // namespace media
142