Question

Need help with x86 NASM Assembly Arrays. I cannot find a clear explanation on the internet of how to print arrays and sort through them. So far I only know how to declare an array.

Here is my code: ARRAY DW 0, 32, 54, 26, 78, 10, 12, 44, 16, 18, 13, 72, 24, 86, 9, 30

Please show me how I would go about printing this array.

Answer 1

You cannot print a number, you first need to convert it to ASCII. For example:-

1. include '../../include/syscalls32.inc'
2. section .bss
3. section .data
4. array dd 1,2,3,4,5
5. arraylen equ ($ - array) / 4 ; array length * 4 = number of elements
6. section .text
7. global _start:
8. _start:
9. mov esi, array ; get pointer to array
10. mov edi, arraylen - 1 ; edi = number of array elements
11. .PrintArray:
12. mov edx, 1 ; print 1 byte
13. mov ecx, [esi] ; get current array element
14. add ecx, 48 ; add 48 to convet to ASCII
15. push ecx ; push to stack since we need an address of item to print
16. mov ecx, esp ; mov address of char to ecx
17. mov ebx, stdout
18. mov eax, sys_write
19. int 80h ; now print it
20. pop ecx ; balance stack
21. add esi, 4 ; get next element, 4 because it's an array of dwords
22. dec edi ; decrease loop counter
23. jns .PrintArray ; if edi ! -1 continue loop
24. .PrintLineFeed:
25. sub esp, 4
26. mov byte [esp], 10
27. mov edx, 1
28. mov ecx, esp
29. mov ebx, stdout
30. mov eax, sys_write
31. int 80h
32. add esp, 4 ; not needed since next call is exit, but learn good techniques.
33. exit:
34. mov ebx, 0
35. mov eax, sys_exit
36. int 80H