Question

I'm having trouble with my Computer Operation assignment.

1. What is the Zero register used for in the ARMv8 architecture?

2. Can you implement the following code (shown below) in ARMv8 assembly, without using branching? How? Show your code

if (i == 0) r = r + 2;

else r = r - 1;

3. Implement the following code (shown below) in ARMv8 assembly down below. Show your code

z = a * (b+c)

4. How can you implement the following c-code for loop in ARMv8 assembly? Show your code

for (k = 0; k < 5; k++)

{ m = m + m;

}

Answer 1

Answer(i) :

Zero Register : As its name is suggesting ,that it ignores all writes to it and all reads of the zero Register,and then it returns 0. In most of the instructions ( not in all instructions ) , zero Register is used.

WZR and XZR are used as a zero Register in ARMv8 architecture.

Size of WZR is 32bits and size of XZR is 64bits.