This block is a non linear function modulo where the input and output
are integer values.
According to the parameter 'Nbit', the output can't overflow
the value 2(Nbit-1) which is defined by the unsigned value of an integer.
The values of the output are then always in
[0;2(Nbit-1)] and this function is like a
Nbit quantifier.
The values of the output are positive or zero.