Optimised Life

CSHIFT was used to count the number of neighbouring live cells. You can optimise the code to do the count with only four CSHIFT operations instead of eight. This requires the use of a temporary array the same size as board. For each array element,

• create the temporary by adding the current value of board to the value of the left and right partners (two CSHIFT s)
• find the upper and lower partners for this temporary array (two more CSHIFT s) and add these to the temporary array
• each element now contains the number of neighbours, plus the original value of the cell. Subtract the original state to obtain the number of neighbours with four CSHIFT s.