Kupyna-based hashing algorithm for the SAMD51 microcontroller in C++

To fully implement the Kupyna hashing algorithm for the SAMD51 microcontroller in C++, you would need several files, each handling a specific part of the algorithm. Below is a list of the elements required, suggested filenames, and a brief description of their functions:

1. kupyna_constants.h - This file contains constants and lookup tables specific to the Kupyna algorithm. It should include the substitution table (S-Box), round constants, and any other predefined values needed for the algorithm.

2. kupyna_utils.h/cpp - Utility functions for the Kupyna algorithm. It should contain functions to manipulate and transform data blocks, like byte substitution, shifting, and mixing columns which are common operations in cryptographic algorithms.

3. kupyna_transform.h/cpp - This file contains the transformation logic of Kupyna, including the implementation of the T⊕ and T+ permutations borrowed from the Kalyna cipher.

4. kupyna_hash.h/cpp - This file, as previously outlined, contains the KupynaHash class, with methods for hashing data using the Kupyna algorithm. It uses the constants, utilities, and transformation functions from other files.

5. kalyna_constants.h - Since Kupyna borrows the structure of permutations from the Kalyna cipher, this file should contain constants and lookup tables that are specific to the Kalyna cipher.

6. kalyna_transform.h/cpp - Similar to kupyna_transform, this file should contain the functions implementing the Kalyna cipher’s T⊕ and T+ permutations.

7. main.cpp - This is the main application file, which contains the main function. It's where you should include the KupynaHash class and showcase how to use it by hashing some sample data.

8. Makefile or CMakeLists.txt - This file will contain the build instructions for compiling your C++ code. This is necessary because you are likely to have multiple source files and need to compile them into a single executable. Makefile is used with the make build system, while CMakeLists.txt is used with the CMake build system.

These components together form a complete implementation of the Kupyna hashing algorithm. To make it efficient and suitable for a microcontroller like the SAMD51, you might need to further optimize the code and ensure that it does not use excessive memory.