Outputs floating-point

I just wanted to create a program that reads a float (i.e. single-precision number) from the keyboard and then outputs it, and there're no warnings or errors, but I couldn't get correct answers, instead, I got 0.00000000. What's wrong with my code? This is my code:

.data 0x10000000
msg1: .asciiz "Please enter a float: "
.text
.globl main
main: addu $s0, $ra, $0  # save $31 in $16
li $v0, 4 # system call for print_str
la $a0, msg1 # address of string to print
syscall
li $v0, 6 # system call for read_float
syscall # the float placed in $f0
mtc1 $t0, $f0# move the number in $t0
sll $t0, $t0, 4 
# print the result
li $v0, 2 # system call for print_float
mfc1 $t0, $f12 # move number to print in $f12
syscall
# restore now the return address in $ra and return from main
addu $ra, $0, $s0 # return address back in $31
jr $ra # return from main

You've got mtc1 and mfc1 backwards.

• mtc1 means GPR -> FPR
• mfc1 means GPR <- FPR

So if we take a look at what this code actually does:

mtc1 $t0, $f0      # Sets $f0 = $t0. You haven't specified a value for $t0 at this point,
                   # but it doesn't really matter since you're not using $f0 any more
                   # after this point.
sll $t0, $t0, 4    # Shifts whatever was in $t0 4 bits to the left.
li $v0, 2          # System call for print_float.
mfc1 $t0, $f12     # Set $t0 = $f12.
syscall            # Calls print_float without having specified a value for $f12.

I don't understand the point of this shift since you say that you just want to print the number that was read, so the above code could be replaced with:

mov.s $f12, $f0
li $v0, 2
syscall

If you do still want to perform that shift for some reason, then you need to change your mtc1 to mfc1 and vice versa.