Page 102 - ARM 64 Bit Assembly Language

88 Chapter 4

The following C program will add together two numbers stored in memory and print the
result.

1 #include <stdio.h>
2 static int x = 5;
3 static int y = 8;
4 int main(void)
5 {
6 int sum;
7 sum=x+y;
8 printf("The sum is %d\n",sum);
9 return 0;
10 }
The equivalent AArch64 assembly program is as follows:

1 .data
2 fmt: .asciz "The sum is %d\n"
3 .align 2
4 x: .word 5
5 y: .word 8
6 .text
7 .type main, %function
8 .global main
9 main:
10 stp x29, x30, [sp, #-16]! // Push FP and LR onto the stack
11 // sum=x+y
12 adr x14, x // Calculate address of x
13 adr x15, y // Calculate address of y
14 ldr x4, [x14] // Load x
15 ldr x5, [x15] // Load y
16 add x1, x4, x5 // x1 = x4 + x5
17
18 // printf("The sum is %d\n", sum)
19 adr x0, fmt // Calculate address of fmt
20 bl printf // Call the printf function
21
22 // return 0
23 mov w0, #0
24 ldp x29, x30, [sp], #16 // Pop FP and LR from the stack
25 ret // Return from main
26 .size main,(. - main)

4.2.2 Logical operations

There are seven basic logical operations:
and Bitwise AND,