My program is supposed to do the following: -Getting continiously an integer from the user (x), -printing the character at the x position in the string. -The program exits when the user inputs 0.
.text
.globl __start
__start:
li $s3,20 #string length
start: li $v0,5
syscall
move $s0,$a0 #integer now in $a0
beq $s0,$zero,exit
li $s1,0 #counter is 0
la $s2,str #address of string now is $s2
loop:lbu $t1,0($s2) #choosing char of string
addi $s1,1 #increment counter by 1
addi $s2,1 #next char
beq $s1,$s0,print #is the char at the position we entered?
j loop
print: lbu $a0,0($t1) #<------------#
li $v0,11
syscall
j start
exit: li $v0,10
syscall
.data
str: .asciiz "abcdefghijklmnopqrst"
I keep getting: "Exception occured at PC=0x00400034" and "Bad address in data stack read: 0x..." exactly when i try to run the line i marked.
$t1
does not contain a valid address at the point where you do lbu $a0,0($t1)
. What you've got in $t1
there is the last character read from the string before you exited your loop
loop.
I really don't see what the point of the loop is. You say that you have a string and and integer X, and you want to print the character at offset X in the string. So just read that character and you're done:
la $a1,string
addu $a1,$a1,$s0 # $a1 = &str[x]. assumes x is in $s0
lbu $a0,($a1) # read the character
li $v0,11
syscall # and print it