Repo created

libs/coding/coding_tests/bit_streams_test.cpp

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+#include "testing/testing.hpp"
+
+#include "coding/bit_streams.hpp"
+#include "coding/reader.hpp"
+#include "coding/writer.hpp"
+
+#include "base/assert.hpp"
+#include "base/bits.hpp"
+
+#include <cstddef>
+#include <cstdint>
+#include <random>
+#include <utility>
+#include <vector>
+
+using namespace std;
+
+namespace
+{
+UNIT_TEST(BitStreams_Smoke)
+{
+  uniform_int_distribution<uint32_t> randomBytesDistribution(0, 255);
+  mt19937 rng(0);
+  vector<pair<uint8_t, uint32_t>> nums;
+  for (size_t i = 0; i < 100; ++i)
+  {
+    uint32_t numBits = randomBytesDistribution(rng) % 8;
+    uint8_t num = static_cast<uint8_t>(randomBytesDistribution(rng) >> (CHAR_BIT - numBits));
+    nums.push_back(make_pair(num, numBits));
+  }
+  for (size_t i = 0; i < 100; ++i)
+  {
+    uint32_t numBits = 8;
+    uint8_t num = static_cast<uint8_t>(randomBytesDistribution(rng));
+    nums.push_back(make_pair(num, numBits));
+  }
+
+  vector<uint8_t> encodedBits;
+  {
+    MemWriter<vector<uint8_t>> encodedBitsWriter(encodedBits);
+    BitWriter<MemWriter<vector<uint8_t>>> bitSink(encodedBitsWriter);
+    for (size_t i = 0; i < nums.size(); ++i)
+      bitSink.Write(nums[i].first, nums[i].second);
+  }
+
+  MemReader encodedBitsReader(encodedBits.data(), encodedBits.size());
+  ReaderSource<MemReader> src(encodedBitsReader);
+  BitReader<ReaderSource<MemReader>> bitsSource(src);
+  for (size_t i = 0; i < nums.size(); ++i)
+  {
+    uint8_t num = bitsSource.Read(nums[i].second);
+    TEST_EQUAL(num, nums[i].first, (i));
+  }
+}
+
+UNIT_TEST(BitStreams_T1)
+{
+  using TBuffer = vector<uint8_t>;
+  using TWriter = MemWriter<TBuffer>;
+
+  TBuffer buf;
+  {
+    TWriter w(buf);
+    BitWriter<TWriter> bits(w);
+
+    bits.Write(0, 3);
+    bits.Write(3, 3);
+    bits.Write(6, 3);
+  }
+
+  TEST_EQUAL(buf.size(), 2, ());
+}
+
+UNIT_TEST(BitStreams_Large)
+{
+  using TBuffer = vector<uint8_t>;
+  using TWriter = MemWriter<TBuffer>;
+
+  uint64_t const kMask = 0x0123456789abcdef;
+
+  TBuffer buf;
+  {
+    TWriter w(buf);
+    BitWriter<TWriter> bits(w);
+
+    for (int i = 0; i <= 64; ++i)
+      if (i <= 32)
+        bits.WriteAtMost32Bits(static_cast<uint32_t>(kMask), i);
+      else
+        bits.WriteAtMost64Bits(kMask, i);
+  }
+
+  {
+    MemReader r(buf.data(), buf.size());
+    ReaderSource<MemReader> src(r);
+    BitReader<ReaderSource<MemReader>> bits(src);
+    for (int i = 0; i <= 64; ++i)
+    {
+      uint64_t const mask = bits::GetFullMask(i);
+      uint64_t const value = i <= 32 ? bits.ReadAtMost32Bits(i) : bits.ReadAtMost64Bits(i);
+      TEST_EQUAL(value, kMask & mask, (i));
+    }
+  }
+}
+}  // namespace