Question

Use the following assembly code to answer the questions below, assuming that:

X19 = f, X20 = g, X21 = i, X22 = &a

LDUR X19, [X22, #0]

LDUR X20, [X22, #8]

ADDI X21, XZR, #0

LOOP: SUB X9, X19, X20

CBZ ENDLOOP

ADDI X19, X19, #1

ADDI X21, X21, #1

B LOOP

ENDLOOP: STUR X21, [X22, #16]

a.What value would the assembler insert for ENDLOOP in the CBZ instruction?

b. What value would the assembler insert for LOOP in the B instruction?

c.If a[0] = 5 and a[1] = 8, what value will be stored in a[2]?

d. How many R, D, I, B, and CBZ instructions are executed if a[0] = 5 and a[1] = 8?

Answer 1

A. if X9 =0 then CBZ execute succesfully then it goto to ENDLOOP so CBZ must be zero.

B. It is branch unconditionally to instruction labeled to LOOP.

C. It is a counter that will increase till a[0] become equal to a[1] So answer would be 3.

D. --