tree adder

1)N=bits pou prepei na athroisw kai input to shma mou
2) exw ena component enan adder me inputs:a,b kai output:c=====> adder(a,b,c)
3) exw array apo signals gia na ta exw ekei gia na ginei swsta to port map. kanw assign ekei ta outputs ton adders. 
este oti to leme out array. epishs to megethos tou einai N-1 kai exei ta outputs twn endiameswn adders. esy tha oriseis to bitwidth.
gia n>4
for i in 0 to log2(N) - 2:
  for j in 0 to N/2 - 2*i - 1:
      if i==0 generate:
          adder(input(2*j),input(2*j+1),out(j))
      else generate:
          adder(out((i-1)*N/2 +j), out ((i-1)*N/2 +1 +j), out(i*N/2 + j))
adder(out(N - 4),out(N -3),out(N-2))

exeis to teliko apotelesma sthn thesh out(N-2)