Databases
StackOverflow2013
Postsdbo
POWhen applying the operation OR to two numbers in assembly, why do I always get one value regardless?
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POWhen applying the operation OR to two numbers in assembly, why do I always get one value regardless?
    primarykey
    data
    text
    <pre><code>SYS_EXIT equ 1 SYS_READ equ 3 SYS_WRITE equ 4 STDIN equ 0 STDOUT equ 1 segment .data msg1 db "Enter two digits: ", 0xA,0xD len1 equ $- msg1 msg2 db "Result: ", 0xA,0xD len2 equ $- msg2 segment .bss num1 resb 1 num2 resb 1 res resb 1 segment .text global _start _start: ; disp msg mov eax, SYS_WRITE mov ebx, STDOUT mov ecx, msg1 mov edx, len1 int 0x80 ; enter num1 mov eax, SYS_READ mov ebx, STDIN mov ecx, num1 mov edx, 2 int 0x80 ; print num1 mov eax, SYS_WRITE mov ebx, STDOUT mov ecx, num1 mov edx, 2 int 0x80 ; enter num2 mov eax, SYS_READ mov ebx, STDIN mov ecx, num2 mov edx, 2 int 0x80 ; print num2 mov eax, SYS_WRITE mov ebx, STDOUT mov ecx, num2 mov edx, 2 int 0x80 ; move first to eax, second to ebx mov eax, num1 sub eax, byte '0' mov ebx, num2 sub ebx, byte '0' ; or them and store the result in eax, and then eax in res or eax, ebx add eax, byte '0' mov [res], eax ; disp result msg mov eax, SYS_WRITE mov ebx, STDOUT mov ecx, msg2 mov edx, len2 int 0x80 ; write result mov eax, SYS_WRITE mov ebx, STDOUT mov ecx, res mov edx, 1 int 0x80 outprog: mov eax,1 ;system call number (sys_exit) int 0x80 ;call kernel </code></pre> <p>In the segment of code above, I wish to take two digits as input, or them, and display the result. However, when I compile and run this code, no matter which input I give the program, the program always return the character <code>]</code>. I am fairly new to programming in assembly and I am not entirely sure as to why this is happening. I've done a bit of research and found that the ascii values for <code>]</code> are (in order dec, hex): 93, 5D, however, I do not know what correlation that character has with the code I have written. Any explanation as to why this is happening and advice as to how to avoid such bugs in the future would be wonderful. </p>
    singulars
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PTQuestion
    1. USnrz
    1. USSwarage
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. COYou can't use `resb 1` for something that you intend to hold more than 1 byte (like `num1`, `num2` and `res`).
      singulars
      1. POWhen applying the operation OR to two numbers in assembly, why do I always get one value regardless?
      1. USMichael
    2. COI do intend to have them hold one byte, since I want them to be one character/digit.
      singulars
      1. POWhen applying the operation OR to two numbers in assembly, why do I always get one value regardless?
      1. USSwarage
    3. COWell, your code says otherwise. For example: `mov [res], eax`
      singulars
      1. POWhen applying the operation OR to two numbers in assembly, why do I always get one value regardless?
      1. USMichael
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload