Assembly MIPS: Reverse printing two strings

Question

Lets say that you type a name first and a surname last and you want the program to print the surname first and then the name.

fe

Gabe

Newell

Newell

Gabe

Ι tried to make just that:

.data  
first: .word
second: .word

.text
.globl main 
main: 

li       $v0, 8 
la       $a0, first
la   $a1, 20 
syscall

move     $s1, $a0

la       $a0, second
la   $a1, 20 
syscall

li   $v0, 4
la       $a0, second
syscall
     
move     $a0, $s1

la       $a0, 0($s1)
syscall

li $v0, 10
syscall

but at the output it gives me: newell newell

So, what it the problem here?

Answer 1

You didn't set aside enough space for the names; .word only sets aside enough for an integer (2 or 4 bytes, probably the latter).

Use .space instead.

Then, to print the first name, you need to load the address of first into $a0 before making the syscall ; $s1 does not have the value you think it does.