Use assembly to write the sum cos also the delay subroutineS

Use assembly to write the sum cos also the delay subroutine?

Solution

/* save file sum.s and you can run in gcc compiler */
/* This is the assembly program to add two variables together and print the result*/

/*Data section */

.data
.baligan 4
result : .asciz \"\ %d + %d = %d\ \"
x :   .word 33         @ .word indicates integer variables
y:     .word 44
z: .word   0           @ z containts the result of a+b

/* Code section */

.text
.global main
.extern printf

main:

   push   {ip,lr} @Used to push return address and dummy register for alignment
  
   ldr   r1,=x       @used to get address of x into r1
  
   ldr   r1,[r1]       @used to get x into r1

   ldr   r2,=y       @used to get address of x into r2

   ldr   r2,[r2]       @used to get y into r2

   add   r1,r1,r2   @adding r1 and r2 and sotring the result into r1

   ldr   r2,=z       @used to get address of z into r2

   str   r1,[r1]       @it sotres r1 into z

   ldr    r0,=result   @used to get address of result into r0

   ldr   r1,=x       @ r1 <-   x
  
   ldr   r1,[r1]      

   ldr   r2,=x       @ r2 <- y

   ldr   r2,[r2]

   ldr   r3,=z       @ r3 <- z

   ldr    r3,[r3]

   b1   printf       @print result and pass params into r1,r2 and r3

   pop   {ip,pc}       @pop   return address into pc