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
from bitcell_base_array import bitcell_base_array
from tech import cell_properties
from sram_factory import factory
from vector import vector
from globals import OPTS


class replica_column(bitcell_base_array):
    """
    Generate a replica bitline column for the replica array.
    Rows is the total number of rows i the main array.
    rbl is a tuple with the number of left and right replica bitlines.
    Replica bit specifies which replica column this is (to determine where to put the
    replica cell relative to the bottom (including the dummy bit at 0).
    """

    def __init__(self, name, rows, rbl, replica_bit, column_offset=0):
        super().__init__(rows=sum(rbl) + rows + 2, cols=1, column_offset=column_offset, name=name)

        self.rows = rows
        self.left_rbl = rbl[0]
        self.right_rbl = rbl[1]
        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
        self.column_offset = column_offset

        debug.check(replica_bit != 0 and replica_bit != rows,
                    "Replica bit cannot be the dummy row.")
        debug.check(replica_bit <= self.left_rbl or replica_bit >= self.total_size - self.right_rbl - 1,
                    "Replica bit cannot be in the regular array.")
        if OPTS.tech_name == "sky130":
            debug.check(rows % 2 == 0 and (self.left_rbl + 1) % 2 == 0,
                        "sky130 currently requires rows to be even and to start with X mirroring"
                        + " (left_rbl must be odd) for LVS.")

        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):

        self.create_all_bitline_names()
        self.create_all_wordline_names()
        self.add_pin_list(self.all_bitline_names, "OUTPUT")
        self.add_pin_list(self.all_wordline_names, "INPUT")

        self.add_pin("vdd", "POWER")
        self.add_pin("gnd", "GROUND")

    def add_modules(self):
        self.replica_cell = factory.create(module_type="replica_{}".format(OPTS.bitcell))
        self.add_mod(self.replica_cell)
        self.dummy_cell = factory.create(module_type="dummy_{}".format(OPTS.bitcell))
        self.add_mod(self.dummy_cell)
        try:
            edge_module_type = ("col_cap" if cell_properties.bitcell.end_caps else "dummy")
        except AttributeError:
            edge_module_type = "dummy"
        self.edge_cell = factory.create(module_type=edge_module_type + "_" + OPTS.bitcell)
        self.add_mod(self.edge_cell)
        # Used for pin names only
        self.cell = factory.create(module_type="bitcell")

    def create_instances(self):

        try:
            end_caps_enabled = cell_properties.bitcell.end_caps
        except AttributeError:
            end_caps_enabled = False

        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)
                self.connect_inst(self.get_bitcell_pins(row, 0))
            elif row==self.replica_bit:
                self.cell_inst[row]=self.add_inst(name=name,
                                                  mod=self.replica_cell)
                self.connect_inst(self.get_bitcell_pins(row, 0))
            elif (row == 0 or row == self.total_size - 1):
                self.cell_inst[row]=self.add_inst(name=name,
                                                  mod=self.edge_cell)
                if end_caps_enabled:
                    self.connect_inst(self.get_bitcell_pins_col_cap(row, 0))
                else:
                    self.connect_inst(self.get_bitcell_pins(row, 0))
            else:
                self.cell_inst[row]=self.add_inst(name=name,
                                                  mod=self.dummy_cell)
                self.connect_inst(self.get_bitcell_pins(row, 0))

    def place_instances(self):
        from tech import cell_properties
        # 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

        # if our bitcells are mirrored on the y axis, check if we are in global
        # column that needs to be flipped.
        dir_y = False
        xoffset = 0
        if cell_properties.bitcell.mirror.y and self.column_offset % 2:
            dir_y = True
            xoffset = self.replica_cell.width

        for row in range(self.total_size):
            # name = "bit_r{0}_{1}".format(row, "rbl")
            dir_x = cell_properties.bitcell.mirror.x and (row + rbl_offset) % 2

            offset = vector(xoffset, self.cell.height * (row + (row + rbl_offset) % 2))

            if dir_x and dir_y:
                dir_key = "XY"
            elif dir_x:
                dir_key = "MX"
            elif dir_y:
                dir_key = "MY"
            else:
                dir_key = ""

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

    def add_layout_pins(self):
        """ Add the layout pins """

        for port in self.all_ports:
            bl_pin = self.cell_inst[0].get_pin(self.cell.get_bl_name(port))
            self.add_layout_pin(text="bl_{0}_{1}".format(port, 0),
                                layer=bl_pin.layer,
                                offset=bl_pin.ll().scale(1, 0),
                                width=bl_pin.width(),
                                height=self.height)
            bl_pin = self.cell_inst[0].get_pin(self.cell.get_br_name(port))
            self.add_layout_pin(text="br_{0}_{1}".format(port, 0),
                                layer=bl_pin.layer,
                                offset=bl_pin.ll().scale(1, 0),
                                width=bl_pin.width(),
                                height=self.height)

        try:
            end_caps_enabled = cell_properties.bitcell.end_caps
        except AttributeError:
            end_caps_enabled = False

        if end_caps_enabled:
            row_range_max = self.total_size - 1
            row_range_min = 1
        else:
            row_range_max = self.total_size
            row_range_min = 0

        for port in self.all_ports:
            for row in range(row_range_min, row_range_max):
                wl_pin = self.cell_inst[row].get_pin(self.cell.get_wl_name(port))
                self.add_layout_pin(text="wl_{0}_{1}".format(port, row),
                                    layer=wl_pin.layer,
                                    offset=wl_pin.ll().scale(0, 1),
                                    width=self.width,
                                    height=wl_pin.height())

        # Supplies are only connected in the ends
        for (index, inst) in self.cell_inst.items():
            for pin_name in ["vdd", "gnd"]:
                if inst in [self.cell_inst[0], self.cell_inst[self.total_size - 1]]:
                    self.copy_power_pins(inst, pin_name)
                else:
                    self.copy_layout_pin(inst, pin_name)

    def get_bitline_names(self, port=None):
        if port == None:
            return self.all_bitline_names
        else:
            return self.bitline_names[port]

    def get_bitcell_pins(self, row, col):
        """ 
        Creates a list of connections in the bitcell,
        indexed by column and row, for instance use in bitcell_array 
        """
        bitcell_pins = []
        for port in self.all_ports:
            bitcell_pins.extend([x for x in self.get_bitline_names(port) if x.endswith("_{0}".format(col))])
        bitcell_pins.extend([x for x in self.all_wordline_names if x.endswith("_{0}".format(row))])
        bitcell_pins.append("vdd")
        bitcell_pins.append("gnd")

        return bitcell_pins

    def get_bitcell_pins_col_cap(self, row, col):
        """ 
        Creates a list of connections in the bitcell,
        indexed by column and row, for instance use in bitcell_array
        """
        bitcell_pins = []
        for port in self.all_ports:
            bitcell_pins.extend([x for x in self.get_bitline_names(port) if x.endswith("_{0}".format(col))])
        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)