palindrome.asm

.data
hi: .asciiz "aabbaa"

.text
main:
    sub $sp, $sp, 4
    sw $ra, 0($sp)
    sub $sp, $sp, 4
    sw $fp, 0($sp)
    move $fp, $sp

    sub $sp, $sp, 4
    la $t0, hi
    sw $t0, 0($sp)
    jal is_palindrome
    add $sp, $sp, 4

    move $sp, $fp
    lw $fp, 0($sp)
    add $sp, $sp, 4
    lw $ra, 0($sp)
    add $sp, $sp, 4
    jr $ra

is_palindrome:
    sub $sp, $sp, 4
    sw $ra, 0($sp)
    sub $sp, $sp, 4
    sw $fp, 0($sp)
    move $fp, $sp

    sub $sp, $sp, 4
    sw $s0, 0($sp)

    li $s0, 0 # s0 := <len of string>
    lw $t0, 8($fp)
    lb $t1, 0($t0)
find_len_loop:
    beqz $t1, end_find_len_loop
    add $s0, $s0, 1
    add $t0, $t0, 1
    lb $t1, 0($t0)
    j find_len_loop
end_find_len_loop:

    li $v0, 0
    li $t0, 0
    sub $t1, $s0, 1
is_palindrome_loop:
    bge $t0, $t1, end_is_palindrome_loop
    lw $t2, 8($fp)
    add $t2, $t2, $t0
    lb $t2, 0($t2)
    lw $t3, 8($fp)
    add $t3, $t3, $t1
    lb $t3, 0($t3)
    bne $t2, $t3, return_is_palindrome
    add $t0, $t0, 1
    sub $t1, $t1, 1
    j is_palindrome_loop
end_is_palindrome_loop:
    li $v0, 1

return_is_palindrome:
    lw $s0, 0($sp)
    add $sp, $sp, 4

    lw $fp, 0($sp)
    add $sp, $sp, 4
    lw $ra, 0($sp)
    add $sp, $sp, 4
    move $sp, $fp
    jr $ra