bit_reader_unittest.cc 4.6 KB

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  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. #include "media/base/bit_reader.h"
  5. #include <stddef.h>
  6. #include <stdint.h>
  7. #include "testing/gtest/include/gtest/gtest.h"
  8. namespace media {
  9. static void SetBit(uint8_t* buf, size_t size, size_t bit_pos) {
  10. size_t byte_pos = bit_pos / 8;
  11. bit_pos -= byte_pos * 8;
  12. DCHECK_LT(byte_pos, size);
  13. buf[byte_pos] |= (1 << (7 - bit_pos));
  14. }
  15. TEST(BitReaderTest, NormalOperationTest) {
  16. uint8_t value8;
  17. uint64_t value64;
  18. // 0101 0101 1001 1001 repeats 4 times
  19. uint8_t buffer[] = {0x55, 0x99, 0x55, 0x99, 0x55, 0x99, 0x55, 0x99};
  20. BitReader reader1(buffer, 6); // Initialize with 6 bytes only
  21. EXPECT_TRUE(reader1.ReadBits(1, &value8));
  22. EXPECT_EQ(value8, 0);
  23. EXPECT_TRUE(reader1.ReadBits(8, &value8));
  24. EXPECT_EQ(value8, 0xab); // 1010 1011
  25. EXPECT_TRUE(reader1.ReadBits(7, &value64));
  26. EXPECT_TRUE(reader1.ReadBits(32, &value64));
  27. EXPECT_EQ(value64, 0x55995599u);
  28. EXPECT_FALSE(reader1.ReadBits(1, &value8));
  29. value8 = 0xff;
  30. EXPECT_TRUE(reader1.ReadBits(0, &value8));
  31. EXPECT_EQ(value8, 0);
  32. BitReader reader2(buffer, 8);
  33. EXPECT_TRUE(reader2.ReadBits(64, &value64));
  34. EXPECT_EQ(value64, 0x5599559955995599ull);
  35. EXPECT_FALSE(reader2.ReadBits(1, &value8));
  36. EXPECT_TRUE(reader2.ReadBits(0, &value8));
  37. }
  38. TEST(BitReaderTest, ReadBeyondEndTest) {
  39. uint8_t value8;
  40. uint8_t buffer[] = {0x12};
  41. BitReader reader1(buffer, sizeof(buffer));
  42. EXPECT_TRUE(reader1.ReadBits(4, &value8));
  43. EXPECT_FALSE(reader1.ReadBits(5, &value8));
  44. EXPECT_FALSE(reader1.ReadBits(1, &value8));
  45. EXPECT_TRUE(reader1.ReadBits(0, &value8));
  46. }
  47. TEST(BitReaderTest, SkipBitsTest) {
  48. uint8_t value8;
  49. uint8_t buffer[] = {0x0a, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15};
  50. BitReader reader1(buffer, sizeof(buffer));
  51. EXPECT_TRUE(reader1.SkipBits(2));
  52. EXPECT_TRUE(reader1.ReadBits(3, &value8));
  53. EXPECT_EQ(value8, 1);
  54. EXPECT_TRUE(reader1.SkipBits(11));
  55. EXPECT_TRUE(reader1.ReadBits(8, &value8));
  56. EXPECT_EQ(value8, 3);
  57. EXPECT_TRUE(reader1.SkipBits(76));
  58. EXPECT_TRUE(reader1.ReadBits(4, &value8));
  59. EXPECT_EQ(value8, 13);
  60. EXPECT_FALSE(reader1.SkipBits(100));
  61. EXPECT_TRUE(reader1.SkipBits(0));
  62. EXPECT_FALSE(reader1.SkipBits(1));
  63. }
  64. TEST(BitReaderTest, VariableSkipBitsTest) {
  65. uint8_t buffer[256] = {0};
  66. // The test alternates between ReadBits and SkipBits.
  67. // The first number is the number of bits to read, the second one is the
  68. // number of bits to skip. The number of bits to read was arbitrarily chosen
  69. // while the number of bits to skip was chosen so as to cover from small skips
  70. // to large skips.
  71. const size_t pattern_read_skip[][2] = {
  72. { 5, 17 },
  73. { 4, 34 },
  74. { 0, 44 },
  75. { 3, 4 }, // Note: aligned read.
  76. { 7, 7 }, // Note: both read&skip cross byte boundary.
  77. { 17, 68 },
  78. { 7, 102 },
  79. { 9, 204 },
  80. { 3, 408 } };
  81. // Set bits to one only for the first and last bit of each read
  82. // in the pattern.
  83. size_t pos = 0;
  84. for (size_t k = 0; k < std::size(pattern_read_skip); ++k) {
  85. const size_t read_bit_count = pattern_read_skip[k][0];
  86. if (read_bit_count > 0) {
  87. SetBit(buffer, sizeof(buffer), pos);
  88. SetBit(buffer, sizeof(buffer), pos + read_bit_count - 1);
  89. pos += read_bit_count;
  90. }
  91. pos += pattern_read_skip[k][1];
  92. }
  93. // Run the test.
  94. BitReader bit_reader(buffer, sizeof(buffer));
  95. EXPECT_EQ(bit_reader.bits_available(), static_cast<int>(sizeof(buffer) * 8));
  96. for (size_t k = 0; k < std::size(pattern_read_skip); ++k) {
  97. const size_t read_bit_count = pattern_read_skip[k][0];
  98. if (read_bit_count > 0) {
  99. int value;
  100. EXPECT_TRUE(bit_reader.ReadBits(read_bit_count, &value));
  101. EXPECT_EQ(value, 1 | (1 << (read_bit_count - 1)));
  102. }
  103. EXPECT_TRUE(bit_reader.SkipBits(pattern_read_skip[k][1]));
  104. }
  105. }
  106. TEST(BitReaderTest, BitsReadTest) {
  107. int value;
  108. bool flag;
  109. uint8_t buffer[] = {0x0a, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15};
  110. BitReader reader1(buffer, sizeof(buffer));
  111. EXPECT_EQ(reader1.bits_available(), 120);
  112. EXPECT_TRUE(reader1.SkipBits(2));
  113. EXPECT_EQ(reader1.bits_read(), 2);
  114. EXPECT_EQ(reader1.bits_available(), 118);
  115. EXPECT_TRUE(reader1.ReadBits(3, &value));
  116. EXPECT_EQ(reader1.bits_read(), 5);
  117. EXPECT_EQ(reader1.bits_available(), 115);
  118. EXPECT_TRUE(reader1.ReadFlag(&flag));
  119. EXPECT_EQ(reader1.bits_read(), 6);
  120. EXPECT_EQ(reader1.bits_available(), 114);
  121. EXPECT_TRUE(reader1.SkipBits(76));
  122. EXPECT_EQ(reader1.bits_read(), 82);
  123. EXPECT_EQ(reader1.bits_available(), 38);
  124. }
  125. } // namespace media