I'm actually not familiar with using the circle pad... The best method I can think of is getting the position of the circle pad via STICK OUT CPX,CPY , and then checking to see if:
CPX is negative (<0)
The absolute value (The value of a number ignoring whether it's negative or positive) of CPX is greater than the absolute value of CPY (IF ABS(CPX) > ABS(CPY) THEN)
0そうだね プレイ済み