Objective

Write an ARM program that takes two integers as input, x and y, and recursively calculates xy.

Requirements and Specifications

Your inputs x and y cannot be stored as a global variable at any point. This means you cannot store them at a data section address, even when accepting them from scanf; they must be returned from scanf on the stack.

You may use X19-X27 only in your main function.

Recursion requires:

• Save the return address, arguments, and local variables in a new stack frame

• Recursively call procedure with BL

• Unwind the stack by restoring the return address, arguments, and local variables, and deallocating the stack frame

Your exponent function should have the following general form:

power(x, y):

    if x is 0

        return 0

    else if y less than 0

        return 0

    else if y is 0

        return 1

    else

        return x * power(x, y - 1)

Your arguments x and y should be passed to your power function in X0 and X1. Your return value should be placed in X2.

Again, you may use X19-X27 in your main function, but you may not use X19-X27 in your recursive function.

Some assumptions:

• x, y are 32-bit integers

• x0 = 1

• 00 = 0

• xy ≤ 230

IT MUST LOOK LIKE THIS.

SKELETON CODE MUST BE USED

.section .data

input_x_prompt : .asciz "Please enter x: "

input_y_prompt : .asciz "Please enter y: "

input_spec : .asciz "%d"

result : .asciz "x^y = %d\n"

.section .text

.global main

main:

# add code and other labels here

# branch to this label on program completion

exit:

mov x0, 0

mov x8, 93

svc 0

ret

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