.. index:: pair: page; API .. _doxid-dev_guide_c_and_cpp_apis: API === oneDNN has both C and C++ APIs available to users for convenience. There is almost a one-to-one correspondence as far as features are concerned, so users can choose based on language preference and switch back and forth in their projects if they desire. Most of the users choose C++ API though. The differences are shown in the table below. ========================= =================================================================================================== ============================================================== Features **C API** **C++ API** ========================= =================================================================================================== ============================================================== Minimal standard version C99 C++11 Functional coverage Full May require use of the **C API** Error handling Functions return :ref:`status ` Functions throw :ref:`exceptions ` Verbosity High Medium Implementation Completely inside the library Header-based thin wrapper around the **C API** Purpose Provide simple API and stable ABI to the library Improve usability Target audience Experienced users, FFI Most of the users and framework developers ========================= =================================================================================================== ============================================================== Input validation notes ~~~~~~~~~~~~~~~~~~~~~~ oneDNN performs limited input validation to minimize the performance overheads. The user application is responsible for sanitizing inputs passed to the library. Examples of the inputs that may result in unexpected consequences: * Not-a-number (NaN) floating point values * Large ``u8`` or ``s8`` inputs may lead to accumulator overflow * While the ``bf16`` 16-bit floating point data type has range close to 32-bit floating point data type, there is a significant reduction in precision. As oneDNN API accepts raw pointers as parameters it's the calling code responsibility to * Allocate memory and validate the buffer sizes before passing them to the library * Ensure that the data buffers do not overlap unless the functionality explicitly permits in-place computations Memory Alignment Requirements ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ On certain architectures, proper memory alignment is required to maximize efficiency and avoid runtime issues when using oneDNN primitives. Intel 64/AMD64 based processors ------------------------------- No memory alignment requirements. Intel Graphics -------------- For Intel Graphics oneDNN requires a minimum memory alignment of 64 bytes, with 128 bytes recommended for optimal performance. If your use case requires element-wise alignment, as a possible workaround, you can use the reference primitive implementation which provides functional coverage, without performance optimizations. To select the reference implementation, use :ref:`dnnl::primitive_desc::next_impl ` API: .. ref-code-block:: cpp auto pd = ... while (!strstr(pd.impl_info_str(), "ref")) { pd.next_impl(); } // Now pd points to the reference implementation.