lab

bsearch.asm

;bsearch
;read num to search into r1
movx a,@dptr
inc dptr
mov r1,a
;read final element pos into r2
movx a,@dptr
subb a,#1
mov r2,a
mov r3,#0
inc dptr
;save dpl in r7
mov r7,dpl
repeat:
	;if r2<r3, break
	mov a,r2
	clr c
	subb a,r3
	jc nofound
	;find mid in a
	mov a,r2
	add a,r3
	mov b,#2
	div ab
	;find mid element in r6 and pos in r5
	mov r5,a
	add a,r7
	mov dpl,a
	movx a,@dptr
	mov r6,a
	;check if mid element is r1
		
	subb a,r1
	jz found
	jc upper
	lower:
		mov a,r5
		clr c
		subb a,#1
		mov r2,a
		jmp repeat
	upper:
		mov a,r5
		add a,#1
		mov r3,a
		jmp repeat
nofound:
mov a,#10h
mov dpl,a
mov a,#0FFh
movx @dptr,a
jmp ende
found:
mov a,#10h
mov dpl,a
mov a,r5
movx @dptr,a

ende:
sjmp ende