I seem to recall from my work with low power microprocessors, it had to do with how your compiler instructs the cpu to preform bit wise operations. I believe it has something to do with the internal pullups drawing power due to the state of the data in the register at rest.
Eg it is more efficient(or less) to instruct a loop to count down from 50 to 0 rather than up from 0 to 50, both methods result in 50 cycles but one is more efficient.
I seem to recall from my work with low power microprocessors, it had to do with how your compiler instructs the cpu to preform bit wise operations. I believe it has something to do with the internal pullups drawing power due to the state of the data in the register at rest.
Eg it is more efficient(or less) to instruct a loop to count down from 50 to 0 rather than up from 0 to 50, both methods result in 50 cycles but one is more efficient.