.syntax unified
.global main

main:
  @ set up the arguments
  mov r0, 66 @ ass1 mark
  mov r1, 73 @ ass2 mark
  mov r2, 71 @ ass3 mark

  @ call the function
  bl calculate_grade

  @ go to the end loop
  b end

end:
  b end

calculate_grade:
    str lr, [sp, #-4]!

    bl calculate_total_mark
    bl grade_from_mark

    ldr lr, [sp], #4

    bx lr

calculate_total_mark:
  @ do stuff with the arguments
  @ ...
  mov r3, 4
  mov r4, 2

  sdiv r0, r3
  sdiv r1, r3
  sdiv r2, r4

  @ put the result in r0
  add r0, r0, r1
  add r0, r0, r2

  @ go back to where the function was called from
  bx lr

grade_from_mark:
    cmp r0, 50
    it le
    movle r0, 0xf
    it le
    bxle lr

    mov r1, 99
    mov r2, 10

    sub r0, r1, r0
    udiv r0, r2
    add r0, 0xa

    bx lr

grade_from_mark_recursive:
    cmp r0, 50
    it le
    movle r0, 0xf
    it le
    bxle lr

    cmp r0, 50
    itt eq
    movle r0, 0xe
    bx

    cmp r0, 60
    it eq
    movle r0, 0xe

    cmp r0, 70
    it eq
    movle r0, 0xe

    cmp r0, 80
    it eq
    movle r0, 0xe

    cmp r0, 90
    it eq
    movle r0, 0xe