The script flow.txt is the command sequence for synthesis, simulation,
P&R, DRC, LVS and GDS and CIF file creation.

It differs from the standard Alliance flow in sxlib100_orig by looping
thru the synthesis steps to find the quickest netlist; using a 6fF
wireload library as well as a 0fF one; including the delay of the
input cap with a 1kohm resistor and the output driving a 50fF load in
the critical path delay; in layout ensuring that the standard cell
rows are terminated by well tie downs; the connectors are in the right
material; running layout with horizontal and vertical metal-2 options;
ensuring a 1 lambda metal end overlap of via instead of 0.5 lambda;
merging CIF and GDS with existing libraries instead of converting the
AP cells in the final step.

The metal layout design rules differ. In Alliance, metal width is 1
and spacing 3. Here metal width is 2 and spacing is 2, which allows
the extra 0.5 lambda end via overlap.

The script syn_loop is the synthesis part which loops vasy, boom, boog
and loon to find the quickest netlist.

The loon loop alternates between the 0fF and 6fF wireload libraries
to find the netlist with the shortest critical path with the 6fF
wireload.

A script find_crit_path writes out the critical path for the 0fF and
6fF wireload libraries.

The 0fF wireload critical path is 1516ps compared to 2032ps for the
original flow. The 1516 includes an extra 57ps input and 152ps output
delay.The 1516 is probably as quick as it gets, but the 2032 is just
the value coming from one synthesis loop and could be quicker or
slower on another run.

Critical path delay is 1595 ps
Area is               10506 um^2 (at lambda=0.5um)
Gate count               43
Occupancy                77%
