Function adler32

app/src/IO/Checksum.cpp:169–180

* @brief Computes the Adler-32 checksum of the input data. */

 * @brief Computes the Adler-32 checksum of the input data.
 */
static constexpr uint32_t adler32(const char* data, const int length) noexcept
{
  constexpr uint32_t kModAdler = 65521;
  uint32_t a = 1, b = 0;

  for (int i = 0; i < length; ++i) {
    a = (a + static_cast<uint8_t>(data[i])) % kModAdler;
    b = (b + a) % kModAdler;
  }

  return (b << 16) | a;
}

/**
 * @brief Computes a Fletcher-16 checksum.