Assembly - Qtspim

Question

.data
hello: .asciiz "hello "
msg: .asciiz "Enter ur Name: "
buffer: .space 10
.text
.globl main
main:
li $v0 , 4
la $a0 , msg
syscall

li $v0 , 8
la $a0 , buffer
li $a1 , 20

move $t0 , $a0

syscall

li $v0 , 4
la $a0 , hello

syscall

li $v0 , 4
la $a0 , buffer

move $a0 , $t0

syscall

li $v0 , 10

syscall

.end main

//===========

I need To Know What is the advantage of this line (la $a0 , buffer) , as i tried to remove it and nothing changed, I've increased and decreased in the buffer size with the existence of this line and also nothing changed ?! ... So What is advantage of this line ?

Are you asking what that line does? If so don't be shy. If you know what it does, tell us and explain why you think it is unnecessary. — Scott Solmer, Oct 31 '13 at 00:57

score 1 · Answer 1 · answered Oct 31 '13 at 01:09

1

(la $a0 , buffer) is used to load "buffer" address to $a0 to let you write string on it when you put 8 into $v0 and put length of "buffer" into $a1 then syscall

To fix your problem I think syscall must be before move $t0 , $a0 in your code.

answered Oct 31 '13 at 01:09

AmgadMHM

146
8

but the value of the string i've entered is not saved in the buffer so what is the usage of the buffer i saved it in $t0 ? – Abdel-rahman El-Carpenter Oct 31 '13 at 01:29
also the length of the string which i'll write is handled by $a1 – Abdel-rahman El-Carpenter Oct 31 '13 at 01:30
and by default the data is written at $a0, so why i need this buffer to write in it ? – Abdel-rahman El-Carpenter Oct 31 '13 at 01:37
syscall 8 reads a string from stdin and stores it in memory at the address pointed to by `$a0`. Therefore, `$a0` must contain the address of a free chunk of memory that is usable by your program, which is exactly what `la $a0, buffer` is for. – Michael Oct 31 '13 at 08:06
but if i removed la $a0 , buffer the program will continue normally ?? – Abdel-rahman El-Carpenter Nov 02 '13 at 23:11
so how can the buffer size be detected by this line ?? – Abdel-rahman El-Carpenter Nov 02 '13 at 23:12

Assembly - Qtspim

1 Answers1