Hi Shreyansh
Have you tried the comparator function of AtMega 16, it performs something similar to what you require. There are two pins AIN1 and AIN0 which deal with this function. AIN1 is the positive(non-inverting) input and AIN0 is the negative(inverting) input. The output is generated on bit ACO of ACSR register. You could also replace the negative(inverting) pin with one of the 8 ADCs of AtMega 16.
I would also suggest you to go through AtMega 16's datasheet, especially the comparator section, to undersatnd better.
Hope this helps 