@Mitch Bailey @Tim Edwards I am trying to edit an existing layout in magic . I need to add fillers cells to the layout. The sky130_fd_sc_hvl_fill_8.gds file is available in the pdk how I can add this to my layout??

@Tim Edwards Thanks! Also how to save the layout in magic? Should I use save or writeall or write gds.And yes I am using parameterized cells in layout

Use

writeall

.

Where does the the layout gets saved by writeall and how can it be reopened once again where we saved last??

It gets saved in one or more

.mag

files in the location where magic was started (e.g., result of running the shell command

pwd

in the Tcl interpreter). For magic, GDS is an "exported" data format. You should never go from GDS -> mag then from mag -> GDS if you don't want your data potentially altered in the process, because magic has rules for generating derived layers from GDS, and more rules for generating GDS from its layers. Those two sets of rules are not necessarily reflexive.

@Tim Edwards Is there an option to save layout in a specific folder at path different from where magic was started ?

It's a little tricky because subcells retain their locations in the .mag file. If you want to do that for just one or two cells, then load the cell and used the

cellname filepath

command to change the location of the cell (then

writeall

to save to the new location). If you want to migrate a bunch of cells, then just copy the cells to the new location, then read everything in from the top level using

load -dereference

to get rid of all the original path information (then

writeall

to save).

What is ideal way of saving layout of multiple sub-blocks and top level blocks in magic? For xschem, different block schematics and testbench scehamtics are created in different folders and integrated into top-level schematic at some other location. What kind of approach can be followed for magic layouts of sub-blocks and top level layout ?

The magicrc file sets up a search path (command

addpath

) for mag files. In order to be portable, it is probably wise to have the cells in a subdirectory although a sister directory might work too. You can check the first

use

line for each cell in the resultant

mag

file to ensure that you do not have absolute paths.

@Mitch Bailey Is it ok if

inverter_chain.mag

layout file is moved to sub-folder (

inv01

) in attached directory structure.

inverter.mag

cell layout is used inside

inverter_chain.mag

. Any specific points to take care? I could not get what needs to be done with

addpath

or

use

commands as mentioned in your last reply.

Each

mag

file has

use

lines for the cell instances it contains. Some lines have the path to the mag file included like this

use sky130_fd_sc_hd__mux2_8  _16517_ $PDKPATH/libs.ref/sky130_fd_sc_hd/mag

Others don’t

use user_id_programming  user_id_value

For the lines that don’t have an explicit path to the mag file, magic has an internal path search list that begins with the current directory by default. You can modify this path using the

addpath

command. The path is also searched if the cell can not be found in the explicit path. In your example, you have

inverter.mag
inv01/
+- inverter_chain.mag

One way to place the cell would be to use a

../

as an explicit directory path.

use inverter inv1 ../

Maybe you meant the other way.

inverter_chain.mag
inv01/
+- inverter.mag

where

inverter_chain.mag

would contain

use inverter inv1 inv01/

Thanks @Mitch Bailey, got the point now.