atoi() function in MIPS assembler

This is demonstration sample code of the atoi() function in MIPS assembler. Launch EzMIPS, copy the following MIPS code and paste it into EzMIPS. Assemble, Run.

# ------------------ atoi() function in MIPS ----------------- #

.data

szGoodNum:   .asciiz "123"
szBadNum:    .asciiz "12a"
szError:     .ascii  "This string does not represent "
             .asciiz "a decimal integer\n"
szIntegerIs: .asciiz "- The integer number is: "


# -------------------- code section -------------------------- #
.text

    la $s1, szGoodNum      # save string address into $s1
                           # change this to szBadNum to test
    li $t0, 10
    li $t2, 48             # 48 = '0'
    li $t3, 57             # 57 = '9'

# ........................... atoi() ......................... #
atoi:
    lbu $t1, ($s1)         # load unsigned char from string
    
    beq $t1, $zero, print  # is it a NULL terminator?
    blt $t1, $t2, err      # is it < '0' ?
    bgt $t1, $t3, err      # is it > '9' ?

    addi $t1, $t1, -48     # convert $t1's ascii value to decimal
    mul $s2, $s2, $t0      # int_val *= 10
    add $s2, $s2, $t1      # int_val += array[s1] - '0'
    addi $s1, $s1, 1       # $s1 is next char's address
    j atoi                 # go get next char
    
# ....................... print error ........................ #
err:

    la $a0, szError        # address of szError string
    li $v0, 4              # print string
    syscall
    j end

# ....................... print integer ...................... #
print:

    la $a0, szIntegerIs    # address of szIntegerIs string
    li $v0, 4              # print string
    syscall
    
    move $a0, $s2
    li $v0, 1              # print integer
    syscall

# ......................... end .............................. #
end:

    li $v0, 10
    syscall

# ------------------------------------------------------------ #

Please let me know of any suggestions or bugs regarding the code above.

Regards,

Antonis