.title leap ; checks whether or not year is leap year ; returns carry set if true, otherwise clear ; year is assumed to be in r4 .dsabl gbl .psect user$i leap:: mov r4,-(sp) mov r5,-(sp) mov r4,r5 ; copy year clr r4 div #4,r4 ; divide current year by 4 tst r5 ; remainder 0? beq 10$ ; br, leap year tst (pc)+ ; clear carry 10$: sec ; set carry mov (sp)+,r5 mov (sp)+,r4 return .end