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#include "storage/louds/bit_stream.h"

#include <cstddef>
#include <cstdint>
#include <iterator>
#include <limits>
#include <string>

#include "absl/base/casts.h"
#include "absl/log/check.h"

namespace mozc {
namespace storage {
namespace louds {

void BitStream::PushBit(int bit) {
  DCHECK(bit == 0 || bit == 1);

  const size_t shift = num_bits_ % 8;
  if (shift == 0) {
    image_.push_back('\0');
  }
  *image_.rbegin() |= (bit & 1) << shift;
  ++num_bits_;
}

void BitStream::FillPadding32() {
  const size_t remaining = image_.length() % 4;
  if (remaining != 0) {
    image_.append(4 - remaining, '\0');
  }
  num_bits_ = image_.length() * 8;
}

namespace internal {

void PushInt32(size_t value, std::string &image) {
  // Make sure the value is fit in the 32-bit value.
  CHECK_LE(value, std::numeric_limits<uint32_t>::max());

  // Output LSB to MSB.
  image.push_back(absl::implicit_cast<char>(value & 0xFF));
  image.push_back(absl::implicit_cast<char>((value >> 8) & 0xFF));
  image.push_back(absl::implicit_cast<char>((value >> 16) & 0xFF));
  image.push_back(absl::implicit_cast<char>((value >> 24) & 0xFF));
}

}  // namespace internal

}  // namespace louds
}  // namespace storage
}  // namespace mozc
