2022/12/05

【Lecture7】Computer Systems & Networks

General Infotech

SDK6800

Simple Loop

For Loopを使った条件式の例

		bra			start
		.org		$0010
// Define the varibles
num     .byte       12
temp    .byte       0
numFactors .byte    0
i       .byte       0

        .org		$0020
// temp = num && i = num 
start   ldaa        num
        staa        temp
        staa        i

        .org        $0030
// Test if i = 0, and jump to "here" if that was
myloop  tst         i
        beq         here
// temp = temp - 1
        ldaa        temp
        suba        i
        staa        temp
// Check if temp = 0, and jump to "saveFactor" if that was
        tst         temp
        beq         saveFactor
// Check if temp < 0, and jump to "skipFactor" if that was
        bmi         skipFactor
// Check if temp > 0, and jump to "nextFactor" if that was
        bpl         nextFactor
// i --
saveFactor dec      i
// numFactors ++
        inc      numFactors
// temp = num (tempの値を初期化)
        ldaa     num
        staa     temp
// Go back to the loop
        bra myloop
skipFactor dec      i
           ldaa     num
           staa     temp
           bra      myloop
nextFactor bra      myloop
// End the loop
here    nop
		     bra			stop
stop	.end

Algorithm

start with a variable equal to 12
num = 12
temp = num

for each number i from 12 to 1:
	temp = temp - i

	if temp == 0:
		then count i as a factor of num
		i = i - 1
		temp = num
		jump back to top of loop
	else if temp < 0:
		then i can't be a factor of num
		i = i - 1
		temp = num
		jump back to top of loop
	else temp > 0:
		jump back to top of loop	

Multiplication

		bra	start
		.org	$0010
x		.byte	7
y		.byte	9
		.org	$0020
product		.byte	0
		.org	$0030
start		clra
myloop		adda	x
		dec	y
		tst	y
		beq	saveans
		bra	myloop
saveans		staa	product
		bra	stop
stop		.end

General Infotech

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