OpenRAM/compiler/modules/replica_column.py

# See LICENSE for licensing information.
#
# Copyright (c) 2016-2019 Regents of the University of California 
# All rights reserved.
#
import debug
import design
from tech import drc
import contact
from sram_factory import factory
from vector import vector
from globals import OPTS

class replica_column(design.design):
    """
    Generate a replica bitline column for the replica array.
    Rows is the total number of rows i the main array.
    Left_rbl and right_rbl are the number of left and right replica bitlines.
    Replica bit specifies which replica column this is (to determine where to put the 
    replica cell.
    """

    def __init__(self, name, rows, left_rbl, right_rbl, replica_bit):
        design.design.__init__(self, name)

        self.rows = rows
        self.left_rbl = left_rbl
        self.right_rbl = right_rbl
        self.replica_bit = replica_bit
        # left, right, regular rows plus top/bottom dummy cells
        self.total_size = self.left_rbl+rows+self.right_rbl+2
        
        debug.check(replica_bit!=0 and replica_bit!=rows,"Replica bit cannot be the dummy row.")
        debug.check(replica_bit<=left_rbl or replica_bit>=self.total_size-right_rbl-1,
                    "Replica bit cannot be in the regular array.")        

        self.create_netlist()
        if not OPTS.netlist_only:
            self.create_layout()
            
    def create_netlist(self):
        self.add_modules()
        self.add_pins()
        self.create_instances()

    def create_layout(self):
        self.height = self.total_size*self.cell.height
        self.width = self.cell.width 

        self.place_instances()
        self.add_layout_pins()
        self.add_boundary()
        self.DRC_LVS()

    def add_pins(self):
        
        for bl_name in self.cell.get_all_bitline_names():
            self.add_pin("{0}_{1}".format(bl_name,0))

        for row in range(self.total_size):
            for wl_name in self.cell.get_all_wl_names():
                self.add_pin("{0}_{1}".format(wl_name,row))
                    
        self.add_pin("vdd")
        self.add_pin("gnd")

    def add_modules(self):
        self.replica_cell = factory.create(module_type="replica_bitcell")
        self.add_mod(self.replica_cell)
        self.dummy_cell = factory.create(module_type="dummy_bitcell")
        self.add_mod(self.dummy_cell)
        # Used for pin names only
        self.cell = factory.create(module_type="bitcell")
        
    def create_instances(self):
        self.cell_inst = {}
        for row in range(self.total_size):
            name="rbc_{0}".format(row)
            # Top/bottom cell are always dummy cells.
            # Regular array cells are replica cells (>left_rbl and <rows-right_rbl)
            # Replic bit specifies which other bit (in the full range (0,rows) to make a replica cell. 
            if (row>self.left_rbl and row<self.total_size-self.right_rbl-1):
                self.cell_inst[row]=self.add_inst(name=name,
                                                  mod=self.replica_cell)
            elif row==self.replica_bit:
                self.cell_inst[row]=self.add_inst(name=name,
                                                  mod=self.replica_cell)
            else:
                self.cell_inst[row]=self.add_inst(name=name,
                                                  mod=self.dummy_cell)
            self.connect_inst(self.get_bitcell_pins(0, row))
            
    def place_instances(self):

        # Flip the mirrors if we have an odd number of replica+dummy rows at the bottom
        # so that we will start with mirroring rather than not mirroring
        rbl_offset = (self.left_rbl+1)%2
            
        for row in range(self.total_size):
            name = "bit_r{0}_{1}".format(row,"rbl")
            offset = vector(0,self.cell.height*(row+(row+rbl_offset)%2))
            if (row+rbl_offset)%2:
                dir_key = "MX"
            else:
                dir_key = "R0"

            self.cell_inst[row].place(offset=offset,
                                      mirror=dir_key)



    def add_layout_pins(self):
        """ Add the layout pins """
        
        for bl_name in self.cell.get_all_bitline_names():
            bl_pin = self.cell_inst[0].get_pin(bl_name)
            self.add_layout_pin(text=bl_name,
                                layer="metal2",
                                offset=bl_pin.ll(),
                                width=bl_pin.width(),
                                height=self.height)

        for row in range(self.total_size):
            for wl_name in self.cell.get_all_wl_names():
                wl_pin = self.cell_inst[row].get_pin(wl_name)
                self.add_layout_pin(text="{0}_{1}".format(wl_name,row),
                                    layer="metal1",
                                    offset=wl_pin.ll().scale(0,1),
                                    width=self.width,
                                    height=wl_pin.height())

        # For every second row and column, add a via for gnd and vdd
        for row in range(self.total_size):
            inst = self.cell_inst[row]
            for pin_name in ["vdd", "gnd"]:
                self.copy_layout_pin(inst, pin_name)

    def get_bitcell_pins(self, col, row):
        """ Creates a list of connections in the bitcell, 
        indexed by column and row, for instance use in bitcell_array """

        bitcell_pins = []
        
        pin_names = self.cell.get_all_bitline_names()
        for pin in pin_names:
            bitcell_pins.append(pin+"_{0}".format(col))
        pin_names = self.cell.get_all_wl_names()
        for pin in pin_names:
            bitcell_pins.append(pin+"_{0}".format(row))
        bitcell_pins.append("vdd")
        bitcell_pins.append("gnd")
        
        return bitcell_pins
                
    def exclude_all_but_replica(self):
        """Excludes all bits except the replica cell (self.replica_bit)."""
        
        for row, cell in self.cell_inst.items():
            if row != self.replica_bit:
                self.graph_inst_exclude.add(cell)