Finding all instances of a particular cell in a gds using the Python API

nanor000

Hello,

I can list all cells from a GDS but can't find a way to access all cell instances in a layout. All examples I've seen are about creating a new instance of a cell and insert it but I can't find how to access all the instances using the Python API... I understood this should be related to CellInstArray and Instance objects but can't find the missing link

Thank you for your help

Ronan

sekigawa

Hi,

Maybe this method is the one you are searching for.

I recently used it in fishfinder.py at this link.

nanor000

Hi,

Thank you. I was able to get further by using the each_parent_inst method. But I'm still struggling to extract the information I'm looking for (for each instance, I would like to get its position and rotation).
If I print the object, I can see the data I'm after but can't find which field contains the actual information. The vars() / dict does not seem to be implemented as for standard Python objects.

This is the code I'm using (using the gds from the fishfinder example)

#!/usr/bin/env python3
import klayout.db as kdb


def list_all_cell_instances(layout, cell_name):

    target_cell = layout.cell(cell_name)
    if target_cell is None:
        print(f"Cell '{cell_name}' not found in the layout.")
        return

    parentInsts = [item for item in target_cell.each_parent_inst()]
    print(f"Number of parent instances referring to <{cell_name}>: {len(parentInsts)}")
    for inst in parentInsts:
        print(f"-D- inst = {inst}")
        child_inst = inst.child_inst()

        dcell_inst = child_inst.dcell_inst
        print(f"\t inst.child_inst() = {child_inst} ({type(child_inst)})")
        print(
            f"\t  vars(child_inst) : {vars(child_inst)} type(child_inst : ({type(child_inst)}) "
        )
        print(
            f"\t  {dcell_inst}  type : {type(dcell_inst)} vars : {vars(dcell_inst)}  "
        )
        print(f"\t  {dcell_inst.na}  {dcell_inst.nb} {dcell_inst.a}  {dcell_inst.b}")
        print()


layout = kdb.Layout()
layout.read("./leaf_chip.gds.gz")
list_all_cell_instances(layout, "sky130_fd_sc_hd__dfrtp_1")

I get output like this

-D- inst = <klayout.dbcore.ParentInstArray object at 0x7eb5711bb640>
     inst.child_inst() = cell_index=202 m90 1006940,1338240 prop_id=237815 (<class 'klayout.dbcore.Instance'>)
      vars(child_inst) : {} type(child_inst : (<class 'klayout.dbcore.Instance'>) 
      #202 m90 1006.94,1338.24  type : <class 'klayout.dbcore.DCellInstArray'> vars : {}  
      0  0 0,0  0,0

-D- inst = <klayout.dbcore.ParentInstArray object at 0x7eb5711bb6d0>
     inst.child_inst() = cell_index=202 m90 830760,1224000 prop_id=219901 (<class 'klayout.dbcore.Instance'>)
      vars(child_inst) : {} type(child_inst : (<class 'klayout.dbcore.Instance'>) 
      #202 m90 830.76,1224  type : <class 'klayout.dbcore.DCellInstArray'> vars : {}  
      0  0 0,0  0,0

so I see the coordinates and rotation when printing the object . I guess this is because of a proper implementation of str or repr for the object. But vars() return an empty dict... which puzzles me...

sekigawa

Hi,

I think you have almost done it.
I have modified your code, as shown below.

import klayout.db as kdb


def list_all_cell_instances(layout, cell_name):
    # [1] Confirm the presence of "cell_name"
    target_cell = layout.cell(cell_name)
    if target_cell is None:
        print(f"Cell '{cell_name}' not found in the layout.")
        return

    # [2] Get all parent instances that refer to "cell_name"
    parentInsts = [item for item in target_cell.each_parent_inst()]
    print(f"Number of parent instances referring to <{cell_name}>: {len(parentInsts)}")

    # [3] Iterate over all parent instances
    for idx, inst in enumerate(parentInsts):
        # (A) print the header
        print(f"-D- inst = {inst}")

        # (B) get the child instance associated with this parent instance
        child_inst = inst.child_inst()

        # (C) get the micrometer unit version of the basic cell instance array object
        dcell_inst = child_inst.dcell_inst

        # (D) get and print the level-1 properties
        cplx_trans = dcell_inst.cplx_trans
        is_complex = cplx_trans.is_complex()
        print( f"    idx={idx}, cplx_trans=[{cplx_trans}], is_complex={is_complex}" )

        # (E) get and print the level-2 properties
        angle     = cplx_trans.angle
        is_mirror = cplx_trans.is_mirror()
        mag       = cplx_trans.mag
        # angle/mirror code is one of the constants R0, R90, R180, R270, M0, M45, M90 and M135.
        #                                     rot = 0   1    2     3     4   5    6       7
        # rx is the rotation by an angle of x counter clockwise.
        # mx is the mirroring at the axis given by the angle x (to the x-axis).
        rot  = cplx_trans.rot()
        disp = cplx_trans.disp
        print( f"        angle={angle}, is_mirror={is_mirror}, mag={mag}, rot={rot}, disp={disp}" )
        print()


layout = kdb.Layout()
layout.read("./leaf_chip.gds.gz")
list_all_cell_instances(layout, "sky130_fd_sc_hd__dfrtp_1")

Then, I got the outputs:

Number of parent instances referring to <sky130_fd_sc_hd__dfrtp_1>: 139
-D- inst = <klayout.dbcore.ParentInstArray object at 0x14d7a51c54f0>
    idx=0, cplx_trans=[r0 *1 1023.5,1196.8], is_complex=False
        angle=0.0, is_mirror=False, mag=1.0, rot=0, disp=1023.5,1196.8
:
:
:
-D- inst = <klayout.dbcore.ParentInstArray object at 0x14d7a51cab70>
    idx=138, cplx_trans=[m90 *1 830.76,1224], is_complex=False
        angle=180.0, is_mirror=True, mag=1.0, rot=6, disp=830.76,1224

---

• Let's examine these two instances in detail.
• Transformations in KLayout

The child cell

Show only the top cell and the child cell.

Go to the reference point of idx=0.

Go to the reference point of idx=138.

nanor000

Thank you very much. That was all I needed to continue my script. Do you have an explanation why vars() is not working ?

Matthias

@nanor000,

These are Python-wrapped C++ objects. They do not feature a dict slot. Hence no "vars".

Matthias