SOLVED: Arduino 3-input XOR and 3-input XNOR operations
After more testing, the code was simplified (original post updated). Works for all possible byte values. Gives the same results as with Xilinx ISE schematic (logic) or LabVIEW block diagram (both Boolean logic or numeric type).
Test scripts are attached.
XOR3_test.ino (385 Bytes)
XNOR3_test.ino (386 Bytes)