mov  r0,#address0
   mov  r1,#address1
   mov  r2,#size
loop:
   mov  a,@r0
   mov  b,@r1
   cjne a,b,exit
   inc  r0         ;or dec, depending on endianness
   inc  r1
   djnz r2,loop
   ;equal at this point
exit:
   jnc  @address0_is_bigger
   ;@address0_is_smaller