.globl fac2

fac2:
        li    $t0, 1                 # check for base case
        bgt   $a0, $t0, recurse
        li    $v0, 1                 # if so, set return value
        jr    $ra                    #        and return

recurse:
        move  $t1, $a0               # save N
        addi  $a0, $a0, -1           # calc N-1 for recursive call
        addi  $sp, $sp, -4           # save return address on stack
        sw    $ra, ($sp)
        jal   fac2                   # calc (N-1)!
        mul   $v0, $v0, $t1          # multiply that by N

        lw    $ra, ($sp)             # restore return address
        addi  $sp, $sp, 4
        jr    $ra                    #    and return