Initialize Floorplan

This tool initializes floorplan constraints, die/core area, and makes tracks.

Commands

Note

• Parameters in square brackets [-param param] are optional.

• Parameters without square brackets -param2 param2 are required.

Initialize Floorplan

Do note that there are two ways of setting the floorplan dimensions. The user can either specify manually die/core area, or specify the utilization/aspect ratio. If you set both, unexpected behaviour might occur.

• Method 1: Automatic die size calculation Example: initialize_floorplan -utilization 70 -aspect_ratio 1.0 -core_space 0.0 -sites FreePDK45_38x28_10R_NP_162NW_34O

• Method 2: Set die/core area Example: initialize_floorplan -die_area 0 0 2000 2000 -core_area 100 100 1900 1900 -sites FreePDK45_38x28_10R_NP_162NW_34O`

The die area and core area used to write ROWs can be specified explicitly with the -die_area and -core_area arguments. Alternatively, the die and core areas can be computed from the design size and utilization as shown below:

The -site argument determines the basic single-height rows to make. For a hybrid row design the site should have a row pattern. Any sites referenced by an instance in the netlist will also have rows constructed for them.

Additional sites are specified if you wish to have rows for a site that is not used in the nelist but may be needed later. For example, you might not have any double height cells in the incoming netlist but you expect some to be generated by flop clustering later in the flow.

Example computation:

core_area = design_area / (utilization / 100)
core_width = sqrt(core_area / aspect_ratio)
core_height = core_width * aspect_ratio
core = ( core_space_left, core_space_bottom )
      ( core_space_left + core_width, core_space_bottom + core_height )
die =  ( 0, 0 )
      ( core_width + core_space_left + core_space_right,
        core_height + core_space_bottom + core_space_top )

initialize_floorplan
  [-utilization util]
  [-aspect_ratio ratio]
  [-core_space space | {bottom top left right}]
  [-die_area {llx lly urx ury}]
  [-core_area {llx lly urx ury}]
  [-additional_sites site_names]
  [-site site_name]

Options

Switch Name	Description
-utilization	Percentage utilization. Allowed values are double in the range (0-100].
-aspect_ratio	Ratio \(\frac{height}{width}\). The default value is 1.0 and the allowed values are floats [0, 1.0].
-core_space	Space around the core, default 0.0 microns. Allowed values are either one value for all margins or a set of four values, one for each margin. The order of the four values are: {bottom top left right}.
-additional_sites	Tcl list of sites to make rows for (e.g. {SITEXX, SITEYY})
-site	Site name.
-die_area	Die area coordinates in microns (lower left x/y and upper right x/y coordinates).
-core_area	Core area coordinates in microns (lower left x/y and upper right x/y coordinates).

Make Tracks

The initialize_floorplan command removes existing tracks. Use the make_tracks command to add routing tracks to a floorplan.

make_tracks 
    [layer]
    [-x_pitch x_pitch]
    [-y_pitch y_pitch]
    [-x_offset x_offset]
    [-y_offset y_offset]

Options

Switch Name	Description
layer	Select layer name to make tracks for. Defaults to all layers.
-x_pitch, -y_pitch	If set, overrides the LEF technology x-/y- pitch. Use the same unit as in the LEF file.
-x_offset, -y_offset	If set, overrides the LEF technology x-/y- offset. Use the same unit as in the LEFT file.

Insert tieoff cells

This comamnd inserts tiecells.

insert_tiecells 
    tie_pin
    [-prefix inst_prefix]

Options

Switch Name	Description
tie_pin	Indicates the master and port to use to tie off nets. For example, LOGIC0_X1/Z for the Nangate45 library, where LOGIC0_X1 is the master and Z is the output port on the master.
-prefix	Used to control the prefix of the new tiecell names. This will default to TIEOFF_.

Useful Developer Commands

If you are a developer, you might find these useful. More details can be found in the source file or the swig file.

Command Name	Description
microns_to_mfg_grid	Convert microns to manufacturing grid DBU.

Example scripts

Example scripts on running ifp for a sample design of mpd_top are as follows:

./test/upf_test.tcl

Regression tests

There are a set of regression tests in ./test. For more information, refer to this section.

Simply run the following script:

./test/regression

Limitations

FAQs

Check out GitHub discussion about this tool.

License

BSD 3-Clause License. See LICENSE file.