Error in line $9$: Runtime exception at $0$x$00400000$: address out of range $0$x$00000000$

The output should be:

Enter the first string $($max $1024$ character$)$: AGGTAB

Enter the second string $($max $1024$ character$)$: GXTXAYB

The length of LCS is $4$

$.$data

prompt$1$: $.$asciiz "Enter the first string $($max $1024$ characters$)$: $"$

prompt$2$: $.$asciiz "Enter the second string $($max $1024$ characters$)$: $"$

result: $.$asciiz "The length of LCS is: $"$

$.$text $.$globl find$\_$lcs

find$\_$lcs: # Prologue addi $sp$,$ $sp$,-12$ sw $ra$,0($$sp$)$ sw $a$0,4($$sp$)$ sw $a$1,8($$sp$)$

# Load arguments

lw $a$0,0($$a$0)$ # Load address of the first string

lw $a$1,0($$a$1)$ # Load address of the second string

# Check for null pointers

beqz $a$0,$ end$\_$lcs # If first string is null, return $0$

beqz $a$1,$ end$\_$lcs # If second string is null, return $0$

# Base case: if either string is empty, return $0$

lb $t$0,0($$a$0)$ # Load byte from the first string

beq $t$0,$ $zero, end$\_$lcs # If byte is null, return $0$

lb $t$0,0($$a$1)$ # Load byte from the second string

beq $t$0,$ $zero, end$\_$lcs # If byte is null, return $0$

# Compare the first characters of both strings

lb $t$0,0($$a$0)$

lb $t$1,0($$a$1)$

beq $t$0,$ $t$1,$ equal$\_$chars

# If characters are not equal, find LCS by considering both cases

# Case $1$: Exclude first character of s$1$

addi $a$0,$ $a$0,1$

jal find$\_$lcs

move $s$0,$ $v$0$ # Store result in $s$0$

# Case $2$: Exclude first character of s$2$

lw $a$0,4($$sp$)$ # Reload s$1$

addi $a$1,$ $a$1,1$

jal find$\_$lcs

move $s$1,$ $v$0$ # Store result in $s$1$

# Choose the maximum LCS

bge $s$0,$ $s$1,$ end$\_$lcs

move $v$0,$ $s$1$

j end$\_$lcs

equal$\_$chars: # Characters are equal, move to the next characters addi $a$0,$ $a$0,1$ addi $a$1,$ $a$1,1$ jal find$\_$lcs addi $v$0,$ $v$0,1$ # Increment LCS by $1$ j end$\_$lcs

end$\_$lcs: # Epilogue lw $ra$,0($$sp$)$ lw $a$0,4($$sp$)$ lw $a$1,8($$sp$)$ addi $sp$,$ $sp$,12$ jr $ra

# Read the first string

li $v$0,8$

la $a$0,0$x$10010000$ # Buffer for the first string

li $a$1,1024$

syscall

# Prompt user for the second string

li $v$0,4$

la $a$0,$ prompt$2$

syscall

# Read the second string

li $v$0,8$

la $a$0,0$x$10020000$ # Buffer for the second string

li $a$1,1024$

syscall

# Call find$\_$lcs

la $a$0,0$x$10010000$ # Address of the first string

la $a$1,0$x$10020000$ # Address of the second string

jal find$\_$lcs

# Print the result

li $v$0,4$

la $a$0,$ result

syscall

# Print the length of the LCS

move $a$0,$ $v$0$

li $v$0,1$

syscall

# Exit

li $v$0,10$

syscall