# signedOF.s
# MIPS program written to illustrate unsigned addition overflow
# Susan Haller 2/17/03
# Modified: Susan Lincke 2/18/05 

	.data
a:	.word  0xf0000000

	.text   
	.globl main   
main:
	la     $a0,  a                 # t2 = t1 = 0xf0000000 
	lw     $t1, 0($a0)              
	move   $t2,$t1

	addu   $t0, $t1,   $t2         # t0 = t1 + t2
        nor    $t3, $t1,   $zero       # t3 = NOT t1 
                                       # // t3 = 2^32 - t1 - 1
	bltu   $t3, $t2,   overflow    # if (t3 >= t2)

noOverflow:                            #    // No overflow
	addi   $t0, $zero, 1           #    return = 1  // No overflow
	b      end
overflow:	                       # Else // Overflow occured
	addi   $t0, $zero, 2	       #    return = 2  // overflow
end:	
	li     $v0, 10           
	syscall                        # system call(exit)