@micropython.native

This causes the MicroPython compiler to emit native CPU instructions rather than the VM bytecode, skipping the interpreter. Most functions require no adaptation.

@micropython.viper

Does a similar thing as the Native code emitter, except it applies some further optimisations that substantially increase performance for integer arithmetic and manipulations.

Viper provides pointer types to assist the optimiser.

• ptr Pointer to an object.
• ptr8 Points to a byte.
• ptr16 Points to a 16 bit half-word.
• ptr32 Points to a 32 bit machine word.

Also Viper ints are 32-bit machine integers that wrap on overflow, unlike Python’s unlimited integers.

The same python code can drastically give different results in Viper.