Computer Arithmetic Part-II

[Music] let us just summarize the results of stage one so uh in the carry look ahead added of this stage uh we compute the generate and propagate the GP functions for increasing sizes of blocks in a tree like fashion so going to the previous slide uh we initially do it for small blocks of two bit pairs 4 bit pairs 8 16

and 32 so assuming that there are n Bits that we want to add there are total of approximately login levels login to the base two the time per level is 01 which means it's constant time and the reason that it is constant time is because we don't have to do a lot of work to

compute GMP functions uh an and gate in one case and or an and gate in some other in other case so total time for stage one is order of login so that's for stage one so we have not done the addition yet but let's take a look at how uh the addition would be

uh real Iz let us now look at stage two in all its detail so uh recall that this is exactly the same diagram that we have been looking at uh earlier also for stage one there are a few couple of changes so I'll discuss that so in stage one the aim was different the aim was uh

to compute the generate and propagate functions for level by level so we pretty much so so if you would recall the diagram in stage one we are considering we started out with two bit blocks in uh so basically the reason we did that is that an equation for a generate and propagate function for a

two bit block or a two bit system is not that complicated so we started out with that reduces a number of levels and uh then we just created a tree of GP blocks and aggregated this information till we went to the top see a total of uh six levels actually from 0 to five so we