.syntax unified
.cpu cortex-m4
.thumb

.macro BKPT_WRITE addr_src
    mov r1, \addr_src
    mov r0, 0x4
    bkpt 0xAB
.endm

.section .data
    test_string: .asciz "Hello"

.section .text

lab1_v2:
    push {lr}

    ldr r1, =test_string
    BKPT_WRITE r1

    pop {pc}