media/base/bit_reader_unittest.cc

   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
   9 namespace media {
  10
  11 static 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
  18 TEST(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
  44 TEST(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
  55 TEST(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
  74 TEST(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
 120 TEST(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