Format of files

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.hgr files
1st line: Number of nets Number of cells
Rest of the lines: Cells that are part of the net. One line per net. Cells are numbered serially.
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.dim files
1st line: <CORE_Width> <CORE_height> <CORE-to-IO-left/right each> <CORE-to-IO-bottom/top each> <No. of standard cell rows in CORE>
Rest of the lines:
width,height,power of cells in serial order (Serial number as in hgr file)

Width and height are in um and power in uW
No. of standard cell rows includes the empty rows and excludes CORE-to-IO region. 
(CORE-TO-IO region has 2 rows each on top and bottom respectively)
Cell placement should occur only in CORE area. IO placement should occur only in CORE-to-IO region at the boundaries. 
Use center-to-center distance for wirelength evaluation.
There should be one and only one row gap (empty row) between two placed cell rows
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.io files
1st line: Total number of I/O cells (= N)
Rest of the lines: Preferred (x,y) boundary location of the I/O cells (you have to snap it to nearest standard cell row).
The first N cells (as per serial order) in hgr and dim files are the I/O cells
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