# See LICENSE for licensing information.
#
# Copyright (c) 2016-2021 Regents of the University of California and The Board
# of Regents for the Oklahoma Agricultural and Mechanical College
# (acting for and on behalf of Oklahoma State University)
# All rights reserved.
#
import design
import debug
import math
from sram_factory import factory
from vector import vector
from globals import OPTS


class write_mask_and_array(design.design):
    """
    Array of AND gates to turn write mask signal on only when w_en is on.
    The write mask AND array goes between the write driver array and the sense amp array.
    """

    def __init__(self, name, columns, word_size, write_size, offsets=None, column_offset=0):
        super().__init__(name)
        debug.info(1, "Creating {0}".format(self.name))
        self.add_comment("columns: {0}".format(columns))
        self.add_comment("word_size {0}".format(word_size))
        self.add_comment("write_size {0}".format(write_size))

        self.columns = columns
        self.word_size = word_size
        self.write_size = write_size
        self.offsets = offsets
        self.column_offset = column_offset
        self.words_per_row = int(columns / word_size)
        self.num_wmasks = int(math.ceil(word_size / write_size))

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

    def create_netlist(self):
        self.add_modules()
        self.add_pins()
        self.create_and2_array()

    def create_layout(self):
        self.place_and2_array()
        self.add_layout_pins()
        self.add_boundary()
        self.DRC_LVS()

    def add_pins(self):
        for bit in range(self.num_wmasks):
            self.add_pin("wmask_in_{}".format(bit), "INPUT")
        self.add_pin("en", "INPUT")
        for bit in range(self.num_wmasks):
            self.add_pin("wmask_out_{}".format(bit), "OUTPUT")
        self.add_pin("vdd", "POWER")
        self.add_pin("gnd", "GROUND")

    def add_modules(self):
        # Size the AND gate for the number of write drivers it drives, which is equal to the write size.
        # Assume stage effort of 3 to compute the size
        self.and2 = factory.create(module_type="pand2",
                                   size=max(self.write_size / 4.0, 1))

    def create_and2_array(self):
        self.and2_insts = {}
        for bit in range(self.num_wmasks):
            name = "and2_{}".format(bit)
            self.and2_insts[bit] = self.add_inst(name=name,
                                                 mod=self.and2)
            self.connect_inst(["wmask_in_{}".format(bit),
                               "en",
                               "wmask_out_{}".format(bit),
                               "vdd", "gnd"])

    def place_and2_array(self):
        # Place the write mask AND array at the start of each write driver enable length.
        # This ensures the write mask AND array will be directly under the corresponding write driver enable wire.

        # This is just used for measurements, so don't add the module
        self.bitcell = factory.create(module_type=OPTS.bitcell)
        self.driver = factory.create(module_type="write_driver")
        if self.bitcell.width > self.driver.width:
            self.driver_spacing = self.bitcell.width
        else:
            self.driver_spacing = self.driver.width

        self.wmask_en_len = self.words_per_row * (self.write_size * self.driver_spacing)
        debug.check(self.wmask_en_len >= self.and2.width,
                    "Write mask AND is wider than the corresponding write drivers {0} vs {1}.".format(self.and2.width,
                                                                                                      self.wmask_en_len))
        if not self.offsets:
            self.offsets = []
            for i in range(self.columns):
                self.offsets.append((i + self.write_size - 1) * self.driver_spacing)

        self.width = self.offsets[-1] + self.bitcell.width
        self.height = self.and2.height

        write_bits = self.columns / self.num_wmasks
        for i in range(self.num_wmasks):
            base = vector(self.offsets[int(i * write_bits)], 0)
            self.and2_insts[i].place(base)

    def add_layout_pins(self):

        # Create the enable pin that connects all write mask AND array's B pins
        en_pin = self.and2_insts[0].get_pin("B")
        self.add_layout_pin_segment_center(text="en",
                                           layer="m3",
                                           start=vector(0, en_pin.cy()),
                                           end=vector(self.width, en_pin.cy()))

        for i in range(self.num_wmasks):
            # Route the A pin over to the left so that it doesn't conflict with the sense
            # amp output which is usually in the center
            inst = self.and2_insts[i]
            a_pin = inst.get_pin("A")
            a_pos = a_pin.center()
            in_pos = vector(inst.lx(),
                            a_pos.y)
            self.add_via_stack_center(from_layer=a_pin.layer,
                                      to_layer="m2",
                                      offset=in_pos)
            self.add_layout_pin_rect_center(text="wmask_in_{0}".format(i),
                                            layer="m2",
                                            offset=in_pos)
            self.add_path(a_pin.layer, [in_pos, a_pos])

            # Copy remaining layout pins
            self.copy_layout_pin(inst, "Z", "wmask_out_{0}".format(i))

            # Add via connections to metal3 for AND array's B pin
            en_pin = inst.get_pin("B")
            en_pos = en_pin.center()
            self.add_via_stack_center(from_layer=en_pin.layer,
                                      to_layer="m3",
                                      offset=en_pos)

            # Add connection to the supply
            for supply_name in ["gnd", "vdd"]:
                supply_pin = inst.get_pin(supply_name)
                self.add_via_stack_center(from_layer=supply_pin.layer,
                                          to_layer="m1",
                                          offset=supply_pin.center())

        for supply in ["gnd", "vdd"]:
            supply_pin = self.and2_insts[0].get_pin(supply)
            supply_pin_yoffset = supply_pin.cy()
            left_loc = vector(0, supply_pin_yoffset)
            right_loc = vector(self.width, supply_pin_yoffset)
            self.add_path("m1", [left_loc, right_loc])
            for loc in [left_loc, right_loc]:
                self.add_via_stack_center(from_layer=supply_pin.layer,
                                          to_layer="m1",
                                          offset=loc)
                self.copy_power_pin(supply_pin, loc=loc)
