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Subject: RC extraction

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justinchen1980
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11/06/2007 3:27 AM
Hi all, I need some help.Now I am trying to model power of buses. But I don't know how to get the total RC value of selected nets.(there are thousands of nets so it is impossible to do it one by one) I wonder if there is a way of doing it. and another thing I want to ask is that all nets capacitances are 0. I wonder if it is right. Thanks

lisiang
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11/21/2007 11:34 AM
if you use SOCE internal rc extractor, you can use "dbNetCap [dbGetNetByName your_net_name] to report the cap. I am not sure/how if you can report the R this way. If you use a external spef using spefIn spef_file, then you can use "dbNetExtractRCSummary [dbGetNetByName your_net_name] to report both R & C. li siang

eminemshow
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11/21/2007 6:45 PM
lisiang: There is really no way the get the R of a single net in SOC-E, sigh..

lisiang
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11/26/2007 3:02 PM
way to wrok around the R problem 1) extractRC 2) rcOut -spef temp.spef 3) spefIn temp.spef 4) dbNetExtrRCSummary [dbGetNetByName your_net] and that should give you toal Cap, total xCap and total R li siang

eminemshow
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11/27/2007 12:36 AM
Posted By lisiang on 11/26/2007 3:02 PM way to wrok around the R problem 1) extractRC 2) rcOut -spef temp.spef 3) spefIn temp.spef 4) dbNetExtrRCSummary [dbGetNetByName your_net] and that should give you toal Cap, total xCap and total R li siang Thanks, li siang!

justinchen1980
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11/27/2007 12:51 AM
Thank you guys very much, I will try it .

justinchen1980
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11/27/2007 7:00 AM
I have a question for dbNetExtrRCSummary [dbGetNetByName your_net_name] what is the syntax for" your_net_name", if the nets are from ahbso⏟] to ahbsoΎ], how should I input? I did like "dbNetExtrRCSummary [dbGetNetByName ahbso]" but there was an error.

bougantp
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11/27/2007 7:33 AM
You can try to use {} charactere around you net name: dbNetExtrRCSummary [dbGetNetByName {ahbsoΎ]}] Pat.

justinchen1980
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11/27/2007 7:37 AM
thanks, that's helpful

justinchen1980
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11/27/2007 8:21 AM
But still that's for single net , how can I get the the value for all the nets ? for example from ahbso𖓏] to ahbsoΎ].

justinchen1980
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2/01/2008 6:52 AM
does anybody know about what does the values given by dbNetExtrRCSummary stand for : like 17 62.937 0 0 16 204.094, I know 62.937 is capacitance and 204.094 is resistance, what about the others?

BobD
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2/08/2008 8:01 AM
Justin, The fields in dbNetExtrRCSummary stand for: cap_cnt,total_cap,xcap_cnt,total_xcap,res_cnt, total_res For your previous inquiry regarding how to get the value for all of the nets, I believe you're seeing that dbNetExtrRCSummary does not support wildcard matching for the net names you give it. You can help dbNetExtrRCSummary along by imbedding it within a foreach loop where, by some other means, you've captured the nets you're looking for. In my design, I have a bussed net called "r697". It looks like this: [DEV]encounter 21> dbFindNetsByName r697* {r697⎛]} {r697⎚]} {r697⎙]} {r697⎘]} {r697⎗]} {r697⎖]} {r697Η]} {r697Ζ]} {r697Ε]} {r697Δ]} {r697Γ]} {r697Β]} {r697Α]} {r697ΐ]} {r697Ώ]} {r697Ύ]} Once I capture it by wildcard, I can then loop through and call dbNetExtrRCSummary iteratively for each net: [DEV]encounter 22> foreach net [dbFindNetsByName r697*] {Puts "[dbNetExtrRCSummary $net]"} 42 18.7058 0 0 54 149.339 53 28.6919 0 0 65 168.797 39 11.8179 0 0 50 118.105 47 25.3172 0 0 57 157.352 40 16.1687 0 0 50 137.919 33 16.3909 0 0 46 124.05 39 18.2286 0 0 51 138.262 41 14.0841 0 0 56 153.221 41 14.6328 0 0 51 122 50 20.0135 0 0 63 152.456 38 13.516 0 0 51 132.627 44 19.1988 0 0 57 158.185 45 23.8199 0 0 54 148.814 53 22.2221 0 0 65 163.052 41 19.9921 0 0 55 160.046 50 23.8562 0 0 61 180.404 If the pattern you seek to match is more complicated than simple wildcarding will allow, you could use TCL's generic "regexp" to match the name. Or, you could leverage the dbGet command's support for regexp pattern matching. Say you wanted to get just the bits that start with "Ώ": [DEV]encounter 31> dbGet -regexp top.nets.name {r697\Ώ} {r697⎛]} {r697⎚]} {r697⎙]} {r697⎘]} {r697⎗]} {r697⎖]} {r697Ώ]} [DEV]encounter 34> foreach net [dbGet -regexp top.nets.name {r697\Ώ}] {puts "[dbNetExtrRCSummary $net]"} 42 18.7058 0 0 54 149.339 53 28.6919 0 0 65 168.797 39 11.8179 0 0 50 118.105 47 25.3172 0 0 57 157.352 40 16.1687 0 0 50 137.919 33 16.3909 0 0 46 124.05 41 19.9921 0 0 55 160.046 From the discussion in this thread it is clear that there is room for improvement in the way RC extraction information is accessible via TCL. As improved capabilities become available in this area, I will post back to this forum with an update. Thanks to all who posted their suggestions on this topic- great discussion! Hope this helps, Bob

justinchen1980
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2/18/2008 3:30 AM
thanks ,bob , I got it done by writing a script repeating the command, but your way seems better.

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