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#include <library/cpp/testing/gtest/gtest.h>
#include <library/cpp/yt/coding/bit_io.h>
#include <utility>
#include <vector>
namespace NYT {
namespace {
////////////////////////////////////////////////////////////////////////////////
TEST(TBitIOTest, RoundTrip)
{
std::vector<std::pair<ui32, int>> items = {
{0, 0}, {1, 1}, {0, 1}, {5, 3}, {0, 8}, {255, 8}, {12345, 14},
{0, 32}, {0xffffffffu, 32}, {0x12345, 17}, {7, 3}, {1u << 30, 31},
};
std::vector<char> buffer(256, 0);
TBitWriter writer(buffer.data());
for (auto [value, width] : items) {
writer.WriteBits(value, width);
}
writer.Finish();
TBitReader reader(buffer.data());
for (auto [value, width] : items) {
EXPECT_EQ(reader.ReadBits(width), value) << "width=" << width;
}
}
TEST(TBitIOTest, ZeroWidthIsNoop)
{
std::vector<char> buffer(16, 0);
TBitWriter writer(buffer.data());
writer.WriteBits(0, 0);
writer.WriteBits(1, 1);
writer.WriteBits(0, 0);
char* end = writer.Finish();
EXPECT_EQ(end - buffer.data(), 1); // a single bit occupies one byte
TBitReader reader(buffer.data());
EXPECT_EQ(reader.ReadBits(0), 0u);
EXPECT_EQ(reader.ReadBits(1), 1u);
EXPECT_EQ(reader.ReadBits(0), 0u);
}
TEST(TBitIOTest, FlushBoundary)
{
// Many 17-bit writes repeatedly cross the internal 32-bit flush boundary.
constexpr int Count = 1000;
std::vector<char> buffer(Count * 3 + 16, 0);
TBitWriter writer(buffer.data());
for (int i = 0; i < Count; ++i) {
writer.WriteBits(static_cast<ui32>(i) & 0x1ffff, 17);
}
writer.Finish();
TBitReader reader(buffer.data());
for (int i = 0; i < Count; ++i) {
EXPECT_EQ(reader.ReadBits(17), static_cast<ui32>(i) & 0x1ffff) << "i=" << i;
}
}
////////////////////////////////////////////////////////////////////////////////
} // namespace
} // namespace NYT
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