Initial Placement

OpenFPGA Floorplaner

This is dedicated OpenFPGA floorplaner which shape tiles in traditional structure as shown below. This placement class is not dependent iupon the architecture and always applied to homogeneous structure.

There are total two ways

• Initial Placement

Paramater Based (Preferred):

Following figure details the various paramteres referred in this type of floorplanning

              |<---------  GRID_X  --------->|
              |                              |
    ┌───────────┐┌─────────────┐┌──────────────┐┌─────────────┐┌───────────┐  ∧
    │           ││   CBX_TOP   ││              ││             ││           │  |
    │           ││   _WIDTH    ││              ││             ││           │  | CBX_TOP_HEIGHT
    │        ┌──┘└─────────────┘└──┐        ┌──┘└─────────────┘└──┐        │  ⩒
    │        │┌───────────────────┐│        │┌───────────────────┐│        │
    └────────┘│   GRID_CLB_RATIO  │└────────┘│                   │└────────┘
    ┌────────┐│       W/H         │┌────────┐│                   │┌────────┐
    │        ││                   ││        ││                   ││        │
    │  CBY_  ││                   ││   CB_  ││                   ││  CBY_  │
    │  LEFT_ ││                   ││ HEIGHT ││                   ││ RIGHT_ │
    │ HEIGHT ││                   ││ _RATIO ││                   ││ HEIGHT │
    │        ││                   ││        ││                   ││        │
    └────────┘│                   │└────────┘│                   │└────────┘
    ┌────────┐│                   │┌────────┐│                   │┌────────┐
↑   │        │└───────────────────┘│        │└───────────────────┘│        │
|   │        └──┐┌─────────────┐┌──┘        └──┐┌─────────────┐┌──┘        │
|   │           ││  CB_WIDTH_  ││              ││             ││           │  FPGA_SIZE[0],y
|   │           ││    RATIO    ││              ││             ││           │
G   │        ┌──┘└─────────────┘└──┐        ┌──┘└─────────────┘└──┐        │
R   │        │┌───────────────────┐│        │┌───────────────────┐│        │
I   └────────┘│                   │└────────┘│                   │└────────┘
D   ┌────────┐│                   │┌────────┐│                   │┌────────┐
_   │        ││                   ││        ││                   ││        │
Y   │        ││                   ││        ││                   ││        │
|   │        ││                   ││        ││                   ││        │
|   │        ││                   ││        ││                   ││        │
|   │        ││                   ││        ││                   ││        │
|   └────────┘│                   │└────────┘│                   │└────────┘
|   ┌────────┐│                   │┌────────┐│                   │┌────────┐
↓   │        │└───────────────────┘│        │└───────────────────┘│        │
    │        └──┐┌─────────────┐┌──┘        └──┐┌─────────────┐┌──┘        │  ∧
    │           ││ CBX_BOTTOM_ ││              ││             ││           │  |
    │           ││   _WIDTH    ││              ││             ││           │  | CBX_BOTTOM_HEIGHT
    └───────────┘└─────────────┘└──────────────┘└─────────────┘└───────────┘  ⩒
    <----------->                                               <--------->
    CBY_LEFT_WIDTH                                           CBY_RIGHT_WIDTH

Area Based:

• OVERALL_UTILIZATION

• GRID_CLB_UTILIZATION

• SB_UTILIZATION

Common Parameters (All of them are absolute numbers in multiple of SC_HEIGHT or CPP)

• GRID_CLB_CHAN_X and GRID_CLB_CHAN_Y: Grid CLB margins

• CBx_CHAN_X and CBx_CHAN_Y : Connection box X margins

• CBy_CHAN_X and CBy_CHAN_Y : Connection box Y margins

• GPIO_CHAN_X and GPIO_CHAN_Y: GPIO cell margins

Absolute Numbers (In multiple of SC_HEIGHT or CPP)

• GRID_X

• GRID_Y

• CLB_W

• CLB_H

• CBX_WIDTH

• CBY_HEIGHT

• LEFT_CBY_WIDTH

• LEFT_CBY_HEIGHT

• RIGHT_CBY_WIDTH

• RIGHT_CBY_HEIGHT

• TOP_CBX_WIDTH

• TOP_CBX_HEIGHT

• BOTTOM_CBX_WIDTH

• BOTTOM_CBX_HEIGHT

Utilization Based

Ideas:

• Optionally provide a method to apply shaping and placement to the netlist elements

class util.initial_placement.initial_placement(grid, netlist, fpga_grid: FPGAGridGen, debug=False, areaFile=None, padFile=None, gridIO=False, shapingConf=None)

Attributes:

CPP	Contated-poly-pitch (`default`=2)
SC_HEIGHT	Standard cell height (`default`=10)
SCALE	Module level variable documented inline. (`default`=100).
PlacementDB	Stores list of modules i uppose
PlacementDBKey	Module level variable documented inline. (`default`=100).

Methods:

__init__
create_placement	Overrides the base method to create placement information
update_configuration	Overwrite default configuration variables
get_default_configuration
get_variables
figSize
snapDims
ComputeGrid
CreateDatabase
add_clb
add_cbx
add_cby
get_stype
unique
add_sb	Adds switch-blocks in the placement database
add_gridIOH
add_gridIOV
add_pad

CPP = 2

Contated-poly-pitch (`default`=2)

Type:

int

SC_HEIGHT = 10

Standard cell height (`default`=10)

Type:

int

SCALE = 100

Module level variable documented inline. (`default`=100)

Type:

int

PlacementDB = []

Stores list of modules i uppose

Type:

list

PlacementDBKey = {}

Module level variable documented inline. (`default`=100)

Type:

dict

__init__(grid, netlist, fpga_grid: FPGAGridGen, debug=False, areaFile=None, padFile=None, gridIO=False, shapingConf=None)

create_placement()

Overrides the base method to create placement information

update_configuration(shapingConf)

Overwrite default configuration variables

add_sb(xi, yi)

Adds switch-blocks in the placement database

::

d

c | |

b | | e

+—-+ +—-+

a | | Cross Shape

| -lengths {a b c d e f}

+—-+ +—-+

|

| f