5.95 · exercise

Fill in the blank: memory and the stack

Fill in the missing mnemonics, registers, directives, and symbols that complete these AArch64 instructions.

0 of 10 correct

Load a single byte from memory into w20, zero-extending the remaining bits.

w20, [x29, 16]

Store exactly 2 bytes (a halfword) from w21 into memory.

w21, [x29, 20]

Load a 64-bit value using pre-indexed addressing, updating x20 by 10.

ldr x21, [x20, 10]

Load a 32-bit value using post-indexed addressing, moving x28 forward by 8 bytes after the load.

ldr w20, [x28] 8

Add a sign-extended 32-bit register offset (w21) to the base register (x29) during a load.

ldr x22, [x29, w21, ]

Define a macro a_s with a value of 16.

(a_s, 16)

Create an assembler alias that renames register x29 to fp.

fp . x29

Align the following machine instruction on a 4-byte boundary.

. 4

Calculate a stack allocation of -20 bytes while forcing 16-byte alignment.

add sp, sp, -20 &

Set the frame pointer at the beginning of a subroutine.

mov , sp