li t0,0x12345678
li t1,0xFFEDCBA9
li t2,0x1F
li t3,0x44
add t5,t1,t0
add t6,t2,t3
bgeu t5,t0,nocarry # Determine the carry bit.
addi t6,t6,1 # Add the carry bit
nocarry:
# t6 now contains the double-machine-word (64 bit) sum.
# Exit to the caller:
li a0,0
li a7,93
ecall
ebreak