# fact2.mips
# Given a number n in $1, calculate n!.
# Return the result in $1.
# $2 is used as a counter.
#
# Register Usage:
# $1 - Accumulates result
# $2 - Counter of current value to multiply

.globl fact2

fact2:  add $2, $1, $0   # Copy n to $2
        addi $1, $0, 1   # Initialize result to 1
        beq $0, $2, done # If none left, finish
loop:   mult $1, $2      # Multiply result by counter
        mflo $1          # Get product from Lo register
        addi $2, $2, -1  # Decrement counter
        bne $0, $2, loop # If more to do, loop
done:   jr $31           # Return to caller