// add16pg.e   4 four bit stages and carry look ahead

define add16pg(a[16], b[16], cin, s[16], cout)
signal pout[4];
signal gout[4];
signal c[3];
circuits
  a0 use add4pg(a[3:0],   b[3:0],   cin,  s[3:0],   pout[0], gout[0]);
  a1 use add4pg(a[7:4],   b[7:4],   c[0], s[7:4],   pout[1], gout[1]);
  a2 use add4pg(a[11:8],  b[11:8],  c[1], s[11:8],  pout[2], gout[2]);
  a3 use add4pg(a[15:12], b[15:12], c[2], s[15:12], pout[3], gout[3]);
  pg use carryla(pout, gout, cin, c, cout);
end circuits;
end add16pg;