Compare2Files.bat: A Windows Script for Comparing Two Files

IC designers often need to compare and find small differences between two GDSII files -- typically one file is a slight revision of another file and they want to be sure of all of the changes.

To do this, one can use Qckbool's XOR engine. The XOR operator generates the difference between two polygons. If both inputs are identical then the output of XOR is empty. Anything that you do see in an XOR output is the difference.

Compare2Files.bat

The script, Compare2Files.bat, uses the Qckbool XOR engine and the gdsfilt engine to compare two GDSII files layer by layer. Certain assumptions are made:

• Each GDSII file has only a single top level structure

• The GDSII layers in each file are technologically equivalent - i.e. if layer 5 in the first file represents poly, then layer 5 in the second file also represents poly. This is a good assumption when one file is a later version of the same design.

• The differences between the data in the two files is small (we also say pertubational). This is also a valid assumption for revisions of the same design.

Example 1 - Comparing two files

Here is how the batch file looks like...

rem Path to Qckbool engine.
set BINDIR=c:\wcad\qckbool

rem Input files..
set file1=iss.gds
set file2=pad_mod.gds

Rem Shift the layer set in file 1 by 200. Output goes to shifted.sf
%BINDIR%\gdsfilte %file1% shifted.sf = -lyr0-200:200-400 -unixcmdline
erase *.log

rem Combine shifted.sf and file 2 - Output to xor_input.gds
%BINDIR%\gdsfilte shifted.sf xor_input.gds = -unixcmdline -add %file2% -combine xor_input =
erase *.log
erase shifted.sf

rem Perform xor, giving the hint that the layer sets are differ by 200. 
rem The output goes to xor_output.gds where the output data 
rem is shifted by 400 from the original set. Note: We selected to run with 2 threads.
%BINDIR%\newxor xor_input.gds xor_output.gds xor_input = x -output_layer_offset:400 -input_layer_offset:200 +nclip:1,100 -postunion  -thrnum:2

rem Last step is optional: Combine xor_input.gds and xor_output.gds and put the combined data in delta.gds. 
rem This provides a nice way to look at the XOR result. 
rem It would be sufficient to combine the XOR output with only one of the input files.
%BINDIR%\gdsfilte xor_input.gds delta.gds = -unixcmdline -add xor_output.gds -combine xor_input =
erase xor_input.log
erase xor_input.gds

erase *.ssn




Example 2 - Comparing two files with xy offset
This example compares layers 1 and 2 in two different files.

The prep'd files are pruned for layers 1 and 2 only.

The second file is offset against the first by 10,5 microns.


Here is how the batch file looks like...
rem Path to Qckbool engine.
set BINDIR=c:\wcad\qckbool

rem Input files..
set file1=iss.gds
set file2=pad_mod.gds

rem Shift the layer set in file 1 by 200. Output goes to shifted.sf. Include layers 1 and 2. Prune extraneous cells. 
%BINDIR%\gdsfilte %file1% shifted.sf = -lyr0-200:200-400 -unixcmdline -i1,2 -prune
erase *.log

rem Output goes to f2.sf. Include layers 1 and 2. Prune extraneous cells.
%BINDIR%\gdsfilte %file2% f2.sf = -unixcmdline -i1,2 -prune
erase *.log

rem Combine shifted.sf and file 2 - Output to xor_input.gds. Shifted.sf os offset 0,0 while f2.sf is shifted 10,5
%BINDIR%\gdsfilte shifted.sf xor_input.gds = -unixcmdline -add f2.sf -combine xor_input = -offset 0,0 10,5
erase *.log
erase shifted.sf f2.sf

rem Perform xor, giving the hint that the layer sets are differ by 200. 
rem The output goes to xor_output.gds where the output data 
rem is shifted by 400 from the original set. Note: We selected to run with 2 threads. Use boolw32f instead of newxor.
%BINDIR%\boolw32f xor_input.gds xor_output.gds xor_input 401;402 +1x201;+2x202  +nclip:1,100 -postunion  -thrnum:2

rem Last step is optional: Combine xor_input.gds and xor_output.gds and put the combined data in delta.gds. 
rem This provides a nice way to look at the XOR result. 
rem It would be sufficient to combine the XOR output with only one of the input files.
%BINDIR%\gdsfilte xor_input.gds delta.gds = -unixcmdline -add xor_output.gds -combine xor_input =
erase xor_input.log
erase xor_input.gds

erase *.ssn