OpenRAM/compiler/modules/replica_bitcell_array.py

# See LICENSE for licensing information.
#
# Copyright (c) 2016-2021 Regents of the University of California
# All rights reserved.
#

import debug
from base import vector
from base import contact
from .bitcell_base_array import bitcell_base_array
from tech import drc, spice
from tech import cell_properties as props
from globals import OPTS
from sram_factory import factory


class replica_bitcell_array(bitcell_base_array):
    """
    Creates a bitcell array of cols x rows and then adds the replica
    and dummy columns and rows.  Replica columns are on the left and
    right, respectively and connected to the given bitcell ports.
    Dummy are the outside columns/rows with WL and BL tied to gnd.
    Requires a regular bitcell array, replica bitcell, and dummy
    bitcell (BL/BR disconnected).
    """
    def __init__(self, rows, cols, rbl=None, left_rbl=None, right_rbl=None, name=""):
        super().__init__(name=name, rows=rows, cols=cols, column_offset=0)
        debug.info(1, "Creating {0} {1} x {2} rbls: {3} left_rbl: {4} right_rbl: {5}".format(self.name,
                                                                                             rows,
                                                                                             cols,
                                                                                             rbl,
                                                                                             left_rbl,
                                                                                             right_rbl))
        self.add_comment("rows: {0} cols: {1}".format(rows, cols))
        self.add_comment("rbl: {0} left_rbl: {1} right_rbl: {2}".format(rbl, left_rbl, right_rbl))

        self.column_size = cols
        self.row_size = rows
        # This is how many RBLs are in all the arrays
        self.rbl = rbl
        # This specifies which RBL to put on the left or right
        # by port number
        # This could be an empty list
        self.left_rbl = left_rbl
        # This could be an empty list
        self.right_rbl = right_rbl
        self.rbls = self.left_rbl + self.right_rbl

        debug.check(sum(self.rbl) >= len(self.left_rbl) + len(self.right_rbl),
                    "Invalid number of RBLs for port configuration.")

        self.create_netlist()
        if not OPTS.netlist_only:
            self.create_layout()

    def create_netlist(self):
        """ Create and connect the netlist """
        self.add_modules()
        self.add_pins()
        self.create_instances()

    def add_modules(self):
        """  Array and dummy/replica columns

        d or D = dummy cell (caps to distinguish grouping)
        r or R = replica cell (caps to distinguish grouping)
        b or B = bitcell
         replica columns 1
         v              v
        bdDDDDDDDDDDDDDDdb <- Dummy row
        bdDDDDDDDDDDDDDDrb <- Dummy row
        br--------------rb
        br|   Array    |rb
        br| row x col  |rb
        br--------------rb
        brDDDDDDDDDDDDDDdb <- Dummy row
        bdDDDDDDDDDDDDDDdb <- Dummy row

          ^^^^^^^^^^^^^^^
          dummy rows cols x 1

        ^ dummy columns  ^
          1 x (rows + 4)
        """
        # Bitcell array
        self.bitcell_array = factory.create(module_type="bitcell_array",
                                            column_offset=1 + len(self.left_rbl),
                                            cols=self.column_size,
                                            rows=self.row_size)

        # Replica bitlines
        self.replica_columns = {}

        for port in self.all_ports:
            if port in self.left_rbl:
                # We will always have self.rbl[0] rows of replica wordlines below
                # the array.
                # These go from the top (where the bitcell array starts ) down
                replica_bit = self.rbl[0] - port
                column_offset = self.rbl[0]

            elif port in self.right_rbl:

                # We will always have self.rbl[0] rows of replica wordlines below
                # the array.
                # These go from the bottom up
                replica_bit = self.rbl[0] + self.row_size + port
                column_offset = self.rbl[0] + self.column_size + 1
            else:
                continue

            self.replica_columns[port] = factory.create(module_type="replica_column",
                                                        rows=self.row_size,
                                                        rbl=self.rbl,
                                                        column_offset=column_offset,
                                                        replica_bit=replica_bit)

        # Dummy row
        self.dummy_row = factory.create(module_type="dummy_array",
                                            cols=self.column_size,
                                            rows=1,
                                            # dummy column + left replica column
                                            column_offset=1 + len(self.left_rbl),
                                            mirror=0)

    def add_pins(self):

        # Arrays are always:
        # bitlines (column first then port order)
        # word lines (row first then port order)
        # dummy wordlines
        # replica wordlines
        # regular wordlines (bottom to top)
        # # dummy bitlines
        # replica bitlines (port order)
        # regular bitlines (left to right port order)
        #
        # vdd
        # gnd

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

    def add_bitline_pins(self):
        # The bit is which port the RBL is for
        for bit in self.rbls:
            for port in self.all_ports:
                self.rbl_bitline_names[bit].append("rbl_bl_{0}_{1}".format(port, bit))
            for port in self.all_ports:
                self.rbl_bitline_names[bit].append("rbl_br_{0}_{1}".format(port, bit))
        # Make a flat list too
        self.all_rbl_bitline_names = [x for sl in self.rbl_bitline_names for x in sl]

        self.bitline_names = self.bitcell_array.bitline_names
        # Make a flat list too
        self.all_bitline_names = [x for sl in zip(*self.bitline_names) for x in sl]

        for port in self.left_rbl:
            self.add_pin_list(self.rbl_bitline_names[port], "INOUT")
        self.add_pin_list(self.all_bitline_names, "INOUT")
        for port in self.right_rbl:
            self.add_pin_list(self.rbl_bitline_names[port], "INOUT")

    def add_wordline_pins(self):

        # Wordlines to ground
        self.gnd_wordline_names = []

        for port in self.all_ports:
            for bit in self.all_ports:
                self.rbl_wordline_names[port].append("rbl_wl_{0}_{1}".format(port, bit))
                if bit != port:
                    self.gnd_wordline_names.append("rbl_wl_{0}_{1}".format(port, bit))

        self.all_rbl_wordline_names = [x for sl in self.rbl_wordline_names for x in sl]

        self.wordline_names = self.bitcell_array.wordline_names
        self.all_wordline_names = self.bitcell_array.all_wordline_names

        # All wordlines including dummy and RBL
        self.replica_array_wordline_names = []
        self.replica_array_wordline_names.extend(["gnd"] * len(self.all_ports))
        for bit in range(self.rbl[0]):
            self.replica_array_wordline_names.extend([x if x not in self.gnd_wordline_names else "gnd" for x in self.rbl_wordline_names[bit]])
        self.replica_array_wordline_names.extend(self.all_wordline_names)
        for bit in range(self.rbl[1]):
            self.replica_array_wordline_names.extend([x if x not in self.gnd_wordline_names else "gnd" for x in self.rbl_wordline_names[self.rbl[0] + bit]])
        self.replica_array_wordline_names.extend(["gnd"] * len(self.all_ports))

        for port in range(self.rbl[0]):
            self.add_pin(self.rbl_wordline_names[port][port], "INPUT")
        self.add_pin_list(self.all_wordline_names, "INPUT")
        for port in range(self.rbl[0], self.rbl[0] + self.rbl[1]):
            self.add_pin(self.rbl_wordline_names[port][port], "INPUT")

    def create_instances(self):
        """ Create the module instances used in this design """
        self.supplies = ["vdd", "gnd"]

        # Main array
        self.bitcell_array_inst=self.add_inst(name="bitcell_array",
                                                mod=self.bitcell_array)
        self.connect_inst(self.all_bitline_names + self.all_wordline_names + self.supplies)

        # Replica columns
        self.replica_col_insts = []
        for port in self.all_ports:
            if port in self.rbls:
                self.replica_col_insts.append(self.add_inst(name="replica_col_{}".format(port),
                                                            mod=self.replica_columns[port]))
                self.connect_inst(self.rbl_bitline_names[port] + self.replica_array_wordline_names + self.supplies)
            else:
                self.replica_col_insts.append(None)

        # Dummy rows under the bitcell array (connected with with the replica cell wl)
        self.dummy_row_replica_insts = []
        # Note, this is the number of left and right even if we aren't adding the columns to this bitcell array!
        for port in self.all_ports:
            self.dummy_row_replica_insts.append(self.add_inst(name="dummy_row_{}".format(port),
                                                                mod=self.dummy_row))
            self.connect_inst(self.all_bitline_names + [x if x not in self.gnd_wordline_names else "gnd" for x in self.rbl_wordline_names[port]] + self.supplies)

    def create_layout(self):

        # This creates space for the unused wordline connections as well as the
        # row-based or column based power and ground lines.
        self.vertical_pitch = 1.1 * getattr(self, "{}_pitch".format(self.supply_stack[0]))
        self.horizontal_pitch = 1.1 * getattr(self, "{}_pitch".format(self.supply_stack[2]))
        self.unused_offset = vector(0.25, 0.25)

        # This is a bitcell x bitcell offset to scale
        self.bitcell_offset = vector(self.cell.width, self.cell.height)
        self.col_end_offset = vector(self.cell.width, self.cell.height)
        self.row_end_offset = vector(self.cell.width, self.cell.height)

        # Everything is computed with the main array
        self.bitcell_array_inst.place(offset=self.unused_offset)

        self.add_replica_columns()

        # Array was at (0, 0) but move everything so it is at the lower left
        # We move DOWN the number of left RBL even if we didn't add the column to this bitcell array
        # Note that this doesn't include the row/col cap
        array_offset = self.bitcell_offset.scale(1 + len(self.left_rbl), 1 + self.rbl[0])
        self.translate_all(array_offset.scale(-1, -1))

        self.add_layout_pins()

        lower_left = self.find_lowest_coords()
        upper_right = self.find_highest_coords()
        self.width = upper_right.x - lower_left.x
        self.height = upper_right.y - lower_left.y
        self.translate_all(lower_left)

        self.add_boundary()

        self.DRC_LVS()

    def get_main_array_top(self):
        """ Return the top of the main bitcell array. """
        return self.bitcell_array_inst.uy()

    def get_main_array_bottom(self):
        """ Return the bottom of the main bitcell array. """
        return self.bitcell_array_inst.by()

    def get_main_array_left(self):
        """ Return the left of the main bitcell array. """
        return self.bitcell_array_inst.lx()

    def get_main_array_right(self):
        """ Return the right of the main bitcell array. """
        return self.bitcell_array_inst.rx()

    def get_replica_top(self):
        """ Return the top of all replica columns. """
        return self.dummy_row_insts[0].by()

    def get_replica_bottom(self):
        """ Return the bottom of all replica columns. """
        return self.dummy_row_insts[0].uy()

    def get_replica_left(self):
        """ Return the left of all replica columns. """
        return self.dummy_col_insts[0].rx()

    def get_replica_right(self):
        """ Return the right of all replica columns. """
        return self.dummy_col_insts[1].rx()

    def get_column_offsets(self):
        """
        Return an array of the x offsets of all the regular bits
        """
        offsets = [x + self.bitcell_array_inst.lx() for x in self.bitcell_array.get_column_offsets()]
        return offsets

    def add_replica_columns(self):
        """ Add replica columns on left and right of array """

        # Grow from left to right, toward the array
        for bit, port in enumerate(self.left_rbl):
            offset = self.bitcell_offset.scale(-len(self.left_rbl) + bit, -self.rbl[0] - 1) + self.unused_offset
            self.replica_col_insts[bit].place(offset)
        # Grow to the right of the bitcell array, array outward
        for bit, port in enumerate(self.right_rbl):
            offset = self.bitcell_array_inst.lr() + self.bitcell_offset.scale(bit, -self.rbl[0] - 1)
            self.replica_col_insts[self.rbl[0] + bit].place(offset)

        # Replica dummy rows
        # Add the dummy rows even if we aren't adding the replica column to this bitcell array
        # These grow up, toward the array
        for bit in range(self.rbl[0]):
            dummy_offset = self.bitcell_offset.scale(0, -self.rbl[0] + bit + (-self.rbl[0] + bit) % 2) + self.unused_offset
            self.dummy_row_replica_insts[bit].place(offset=dummy_offset,
                                                    mirror="MX" if (-self.rbl[0] + bit) % 2 else "R0")
        # These grow up, away from the array
        for bit in range(self.rbl[1]):
            dummy_offset = self.bitcell_offset.scale(0, bit + bit % 2) + self.bitcell_array_inst.ul()
            self.dummy_row_replica_insts[self.rbl[0] + bit].place(offset=dummy_offset,
                                                                  mirror="MX" if (self.row_size + bit) % 2 else "R0")

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

        # All wordlines
        # Main array wl and bl/br
        for pin_name in self.all_wordline_names:
            pin_list = self.bitcell_array_inst.get_pins(pin_name)
            for pin in pin_list:
                self.add_layout_pin(text=pin_name,
                                    layer=pin.layer,
                                    offset=pin.ll().scale(0, 1),
                                    width=self.width,
                                    height=pin.height())

        # Replica wordlines (go by the row instead of replica column because we may have to add a pin
        # even though the column is in another local bitcell array)
        for (names, inst) in zip(self.rbl_wordline_names, self.dummy_row_replica_insts):
            for (wl_name, pin_name) in zip(names, self.dummy_row.get_wordline_names()):
                if wl_name in self.gnd_wordline_names:
                    continue
                pin = inst.get_pin(pin_name)
                self.add_layout_pin(text=wl_name,
                                    layer=pin.layer,
                                    offset=pin.ll().scale(0, 1),
                                    width=self.width,
                                    height=pin.height())

        for pin_name in self.all_bitline_names:
            pin_list = self.bitcell_array_inst.get_pins(pin_name)
            for pin in pin_list:
                self.add_layout_pin(text=pin_name,
                                    layer=pin.layer,
                                    offset=pin.ll().scale(1, 0),
                                    width=pin.width(),
                                    height=self.height)

        # Replica bitlines
        if len(self.rbls) > 0:
            for (names, inst) in zip(self.rbl_bitline_names, self.replica_col_insts):
                pin_names = self.replica_columns[self.rbls[0]].all_bitline_names
                for (bl_name, pin_name) in zip(names, pin_names):
                    pin = inst.get_pin(pin_name)
                    self.add_layout_pin(text=bl_name,
                                        layer=pin.layer,
                                        offset=pin.ll().scale(1, 0),
                                        width=pin.width(),
                                        height=self.height)

    def analytical_power(self, corner, load):
        """Power of Bitcell array and bitline in nW."""
        # Dynamic Power from Bitline
        bl_wire = self.gen_bl_wire()
        cell_load = 2 * bl_wire.return_input_cap()
        bl_swing = OPTS.rbl_delay_percentage
        freq = spice["default_event_frequency"]
        bitline_dynamic = self.calc_dynamic_power(corner, cell_load, freq, swing=bl_swing)

        # Calculate the bitcell power which currently only includes leakage
        cell_power = self.cell.analytical_power(corner, load)

        # Leakage power grows with entire array and bitlines.
        total_power = self.return_power(cell_power.dynamic + bitline_dynamic * self.column_size,
                                        cell_power.leakage * self.column_size * self.row_size)
        return total_power


    def gen_bl_wire(self):
        if OPTS.netlist_only:
            height = 0
        else:
            height = self.height
        bl_pos = 0
        bl_wire = self.generate_rc_net(int(self.row_size - bl_pos), height, drc("minwidth_m1"))
        bl_wire.wire_c =spice["min_tx_drain_c"] + bl_wire.wire_c # 1 access tx d/s per cell
        return bl_wire

    def graph_exclude_bits(self, targ_row=None, targ_col=None):
        """
        Excludes bits in column from being added to graph except target
        """
        self.bitcell_array.graph_exclude_bits(targ_row, targ_col)

    def graph_exclude_replica_col_bits(self):
        """
        Exclude all replica/dummy cells in the replica columns except the replica bit.
        """

        for port in self.left_rbl + self.right_rbl:
            self.replica_columns[port].exclude_all_but_replica()

    def get_cell_name(self, inst_name, row, col):
        """
        Gets the spice name of the target bitcell.
        """
        return self.bitcell_array.get_cell_name(inst_name + "{}x".format(OPTS.hier_seperator) + self.bitcell_array_inst.name, row, col)

    def clear_exclude_bits(self):
        """
        Clears the bit exclusions
        """
        self.bitcell_array.init_graph_params()