OpenChess

I was wondering if it is better to have little-endian representation of squares(a1=0,h8=63) or big-endian(h1=0,a8=63).
Currently I am using big-endian but I see that engines like Stockfish use little-endian so I was wondering if little-endian can be optimized to be faster.

it is a matter of personal choice. i originally had my code in what you are calling "big endian", because it was easier to display boards on the console since the looping was going from 0 to 63 and the white piece were usually shown on the bottom of the board display. But as time went on, it got confusing when i examined or tried code from other developers who mostly use the "little endian" style. It wasn't too much work to switch and it all seems to be working now.

The issue is bit numbering. Intel hardware (BSF/BSR) counts LSB as 0, MSB as 63. You should use that numbering scheme to avoid any sort of translation such as the 63 - N I did since I originally numbered the bits to match the Cray architecture. For simplicity I use a1=0, h1=7, a8=56, h8=63, makes move input and output translation a "direct process"...

Makes the bit boards a bit "backward" to visualize since rightmost bit = leftmost square, but then everything else is a direct map.