I writed string to float in MIPS. But there is error. but, i don't know......

where is problem?

.data

intro : .asciiz "\Enter the number : "

out_string: .asciiz "\Input string : "

out_reals: .asciiz " Floating point number detected "

out_float: .asciiz " Floatig point : "

check:.asciiz "."

input: .space 20

.text

.globl main

main:

li $v0,4

la $a0, intro #intro enter

syscall

li $a1,20

li $v0, 8

la $a0, input #read a string into a0

syscall

jal str2float #str -> int

move $s0,$v0

li $v0,4

la $a0,out_float

syscall

li $v0,2

move $a0,$s0

syscall

str2float:

li $t6,0x20

li $t7,0x30

lb $t0,0($a0) # load the first byte into $t1

beq $t0,'-',negint # if sign is -,goto negint

beq $t0,'+',posint # if sign is +,goto posint

j convert

negint:

li $t1,1 # set flag $t1 to 1(represents negative)

add $a0,$a0,1 # goto next ASCII character

j convert # goto convert

posint:

li $t1,0 # set flag $t1 to 0(represents positive)

add $a0,$a0,1 # goto next ASCII character

convert:

li $s0,0 # sum=0

loop:

lb $t0,0($a0) # load the ASCII character into $t1

beq $t0,10,exitloop #if end of string space came

blt $t0,$t6,fail # if $t1 is a non-digit character,return -1

bgt $t0,$t7,fail

sub $t0,$t0,48 # convert ASCII digit to decimal digit

mul $s0,$s0,10 # multiply the previous sum with 10 and

add $s0,$s0,$t0 # the converted digit to sum

add $a0,$a0,1 # goto next ASCII character

j loop # goto loop

exitloop:

beq $t1,0,copy # if sign is +, goto copy

neg $s0,$s0 # if the sign is -, take negation of FP

copy:

move $v0,$s0 # store the converted FP into $v0

jr $ra

fail:

li $v0,-1

Plz change it ....