How to generate a SPEF (write_spef) including coordinate information?

[xlindo]

As the default flow, there is no coordinate information in *CONN following each PORT in the generated 6_final.spef, which is not in coincidence with a normal SPEF format.

E.g., no *C bolow,

...

*CONN
*I *572:B I *D sky130_fd_sc_hd__nand2_1
*I *571:Y O *D sky130_fd_sc_hd__nand2_1

...

Compared with another example in a book,

*D_NET *5423 2.69358 

*CONN 
*I *14207:D I *C 21.7450 94.3150 
*I *14205:D I *C 21.7450 90.4900 
*I *14211:Q O *C 21.4900 83.8800 *D DFFQX1 

*CAP 
1 *5423:10107 *547:12722 0.202686 
2 *5423:10107 *5116:10594 0.104195

....

Any boss help me?

[maliberty]

Coordinates are optional in spef so this is valid. There is code to generate coordinates but we've never used it. We could try enabling but I can't make any guarantees about what it will produce. Do you have a use model for these or are you just comparing to what a book shows?

[xlindo]

Coordinates are optional in spef so this is valid. There is code to generate coordinates but we've never used it. We could try enabling but I can't make any guarantees about what it will produce. Do you have a use model for these or are you just comparing to what a book shows?

I would like to generate the coordinates for later usage. I saw the parameter nodeCoord is in the function writeSPEF (or writeBlock) in netRC.cpp, but the usage is as

void
write_spef(const char* file,
           const char* nets,
           int net_id)
{
  Ext* ext = getOpenRCX();
  Ext::SpefOptions opts;
  opts.file = file;
  opts.nets = nets;
  opts.net_id = net_id;
  
  ext->write_spef(opts);
}

in ext.i, where I guess if the coordinate information is never parsed? So I am not sure how to enable and if it really works.

[xlindo]

Coordinates are optional in spef so this is valid. There is code to generate coordinates but we've never used it. We could try enabling but I can't make any guarantees about what it will produce. Do you have a use model for these or are you just comparing to what a book shows?

FYI, the example with coordinates is at page 545 of Static Timing Analysis for Nanometer Designs: A Practical Approach. Boston, MA: Springer US, 2009. doi: 10.1007/978-0-387-93820-2.

Also, the coordinates are important for RC estimation as the training resources.

[maliberty]

I've added a -coordinates option to write_spef in #3434