# SPDX-License-Identifier: GPL-2.0-or-later
from typing import Optional, Tuple, Union, cast

from pdkmaster.technology import geometry as _geo, primitive as _prm
from pdkmaster.design import circuit as _ckt, library as _lbry

from c4m.pdk import sky130

from . import frame as _frm


__all__ = ["ConnectedSRAM"]


class _io_spec:
    def __init__(self, *,
        sram_signal: Union[str, Tuple[str, str, str]],
        io_type: str, io_number: int,
    ):
        assert io_type in ("io_in", "io_out", "io_analog")
        assert (io_type != "io_inout") or isinstance(sram_signal, tuple)
        self.sram_signal = sram_signal
        self.io_type = io_type
        self.io_number = io_number

    @property
    def prefix(self) -> str:
        if self.io_type in ("io_in", "io_out", "io_inout"):
            return f"io{self.io_number}"
        elif self.io_type == "io_analog":
            return f"ioa{self.io_number}"
        elif self.io_type == "gpio":
            return f"gpio{self.io_number}"
        else:
            raise NotImplementedError(f"io_type == '{self.io_type}'")

    @property
    def toppin_name(self) -> str:
        num = self.io_number
        if self.io_type == "io_in":
            return f"io_in[{num}]"
        elif self.io_type == "io_out":
            return f"io_out[{num}]"
        elif self.io_type == "io_analog":
            return f"io_analog[{num}]"
        else:
            raise NotImplementedError(f"io_type == {self.io_type}")

    @property
    def oeb(self) -> Optional[bool]:
        if self.io_type == "io_in":
            return True
        elif self.io_type == "io_out":
            return False
        else:
            return None


io_specs = (
    _io_spec(sram_signal="a[8]", io_type="io_in", io_number=14),
    _io_spec(sram_signal="a[7]", io_type="io_in", io_number=15),
    _io_spec(sram_signal="a[6]", io_type="io_in", io_number=16),
    _io_spec(sram_signal="a[5]", io_type="io_in", io_number=17),
    _io_spec(sram_signal="a[4]", io_type="io_in", io_number=18),
    _io_spec(sram_signal="a[3]", io_type="io_in", io_number=19),
    _io_spec(sram_signal="a[2]", io_type="io_in", io_number=20),
    _io_spec(sram_signal="a[1]", io_type="io_in", io_number=21),
    _io_spec(sram_signal="a[0]", io_type="io_in", io_number=22),
    _io_spec(sram_signal="clk", io_type="io_in", io_number=23),
    _io_spec(sram_signal="q[7]", io_type="io_out", io_number=13),
    _io_spec(sram_signal="d[7]", io_type="io_in", io_number=12),
    _io_spec(sram_signal="d[6]", io_type="io_in", io_number=11),
    _io_spec(sram_signal="q[6]", io_type="io_out", io_number=10),
    _io_spec(sram_signal="q[5]", io_type="io_out", io_number=9),
    _io_spec(sram_signal="d[5]", io_type="io_in", io_number=8),
    _io_spec(sram_signal="d[4]", io_type="io_in", io_number=7),
    _io_spec(sram_signal="q[4]", io_type="io_out", io_number=6),
    _io_spec(sram_signal="q[3]", io_type="io_out", io_number=5),
    _io_spec(sram_signal="d[3]", io_type="io_in", io_number=4),
    _io_spec(sram_signal="d[2]", io_type="io_in", io_number=3),
    _io_spec(sram_signal="q[2]", io_type="io_out", io_number=2),
    _io_spec(sram_signal="q[1]", io_type="io_out", io_number=1),
    _io_spec(sram_signal="we[0]", io_type="io_in", io_number=0),
    _io_spec(sram_signal="d[1]", io_type="io_in", io_number=26),
    _io_spec(sram_signal="d[0]", io_type="io_in", io_number=25),
    _io_spec(sram_signal="q[0]", io_type="io_out", io_number=24),
    _io_spec(sram_signal="vdd", io_type="io_analog", io_number=4),
    _io_spec(sram_signal="vss", io_type="io_analog", io_number=5),
)
io_sig2spec = {
    spec.sram_signal: spec
    for spec in io_specs
}
io_pin2spec = {
    spec.toppin_name: spec
    for spec in io_specs
}


class ConnectedSRAM(_lbry._Cell[_lbry.Library]):
    def __init__(self, *, lib: _lbry.Library):
        super().__init__(lib=lib, name="ConnectedSRAM")
        tech = lib.tech
        prims = tech.primitives

        stdcells = sky130.stdcelllib.cells

        mem_fab = sky130.Sky130SP6TFactory(lib=self.lib)

        nwm = cast(_prm.Well, prims.nwm)
        li = cast(_prm.MetalWire, prims.li)
        lipin = cast(_prm.Marker, prims["li.pin"])
        mcon = cast(_prm.Via, prims.mcon)
        m1 = cast(_prm.MetalWire, prims.m1)
        m1pin = cast(_prm.Marker, prims["m1.pin"])
        via = cast(_prm.Via, prims.via)
        m2 = cast(_prm.MetalWire, prims.m2)
        m2pin = cast(_prm.Marker, prims["m2.pin"])
        via2 = cast(_prm.Via, prims.via2)
        m3 = cast(_prm.MetalWire, prims.m3)
        m3pin = cast(_prm.Marker, prims["m3.pin"])

        zero_cell = stdcells.zero_x1
        zero_nets = zero_cell.circuit.nets
        _zero_zerolipinbb = zero_cell.layout.bounds(
            mask=lipin.mask, net=zero_nets.zero, depth=1,
        )
        _zero_bb = zero_cell.layout.boundary
        assert _zero_bb is not None

        one_cell = stdcells.one_x1
        _one_bb = one_cell.layout.boundary
        assert _one_bb is not None

        buf_cell = stdcells.buf_x2
        buf_nets = buf_cell.circuit.nets
        _buf_ilipinbb = buf_cell.layout.bounds(mask=lipin.mask, net=buf_nets.i, depth=1)
        _buf_bb = buf_cell.layout.boundary
        assert _buf_bb is not None

        tie_cell = stdcells.tie_diff_w4
        _tie_bb = tie_cell.layout.boundary
        assert _tie_bb is not None

        sram_cell = mem_fab.block(words=512, word_size=8, we_size=1)
        self.a_bits = sram_cell.a_bits
        self.word_size = sram_cell.word_size

        ckt = self.new_circuit()
        layouter = self.new_circuitlayouter()
        layout = layouter.layout


        # vss/vdd for the included standard cells
        #
        dvss_name = "vssd1"
        dvss = ckt.new_net(name=dvss_name, external=True)
        dvss_bb = _frm.toppins[dvss_name]

        dvdd_name = "vccd1"
        dvdd = ckt.new_net(name=dvdd_name, external=True)
        dvdd_bb = _frm.toppins[dvdd_name]


        # Place the SRAM
        #
        # instantiate
        sram = ckt.instantiate(sram_cell, name="sram")

        # place
        _sram_lay = layouter.inst_layout(inst=sram)
        _sram_bb = _sram_lay.boundary
        assert _sram_bb is not None

        x = sky130.tech.on_grid(_frm.boundary.center.x - _sram_bb.center.x)
        y = _frm.boundary.top - 100.0 - _sram_bb.top
        sram_lay = layouter.place(_sram_lay, x=x, y=y)
        sram_bb = sram_lay.boundary
        assert sram_bb is not None


        # Make three rows of to place standard cells in
        #
        dbound = 4.0
        # left
        rot_leftrow = _geo.Rotation.R90
        _tie_rotbb = rot_leftrow*_tie_bb

        x_leftrow = dbound - _tie_rotbb.left

        inst = ckt.instantiate(tie_cell, name="lltie")
        dvss.childports += inst.ports.vss
        dvdd.childports += inst.ports.vdd

        y_tie = dbound - _tie_rotbb.bottom
        lay = layouter.place(inst, x=x_leftrow, y=y_tie, rotation=rot_leftrow)
        nwmbb1 = lay.bounds(mask=nwm.mask)
        lipindvssbb1 = lay.bounds(mask=lipin.mask, net=dvss, depth=1)
        lipindvddbb1 = lay.bounds(mask=lipin.mask, net=dvdd, depth=1)

        inst = ckt.instantiate(tie_cell, name="ultie")
        dvss.childports += inst.ports.vss
        dvdd.childports += inst.ports.vdd

        y_tie = _frm.boundary.top - dbound - _tie_rotbb.top
        lay = layouter.place(inst, x=x_leftrow, y=y_tie, rotation=rot_leftrow)
        nwmbb2 = lay.bounds(mask=nwm.mask)
        lipindvssbb2 = lay.bounds(mask=lipin.mask, net=dvss, depth=1)
        lipindvddbb2 = lay.bounds(mask=lipin.mask, net=dvdd, depth=1)

        shape = _geo.Rect.from_rect(rect=nwmbb1, top=nwmbb2.top)
        layouter.add_wire(net=dvdd, wire=nwm, shape=shape)

        shape = _geo.Rect.from_rect(rect=lipindvssbb1, top=lipindvssbb2.top)
        layouter.add_wire(net=dvss, wire=li, shape=shape)
        w = tech.on_grid(shape.width, mult=2, rounding="floor")
        h = tech.on_grid(shape.height, mult=2, rounding="floor")
        o = tech.on_grid(shape.center)
        lay = layouter.add_wire(
            net=dvss, wire=mcon, origin=o, bottom_width=w, bottom_height=h,
        )
        dvss_leftrowm1bb = lay.bounds(mask=m1.mask)

        shape = _geo.Rect.from_rect(rect=lipindvddbb1, top=lipindvddbb2.top)
        layouter.add_wire(net=dvdd, wire=li, shape=shape)
        w = tech.on_grid(shape.width, mult=2, rounding="floor")
        h = tech.on_grid(shape.height, mult=2, rounding="floor")
        o = tech.on_grid(shape.center)
        lay = layouter.add_wire(
            net=dvdd, wire=mcon, origin=o, bottom_width=w, bottom_height=h,
        )
        dvdd_leftrowm1bb = lay.bounds(mask=m1.mask)

        # right
        rot_rightrow = _geo.Rotation.R90
        _tie_rotbb = rot_rightrow*_tie_bb

        x_rightrow = _frm.boundary.right - dbound - _tie_rotbb.right

        inst = ckt.instantiate(tie_cell, name="lrtie")
        dvss.childports += inst.ports.vss
        dvdd.childports += inst.ports.vdd

        y_tie = dbound - _tie_rotbb.bottom
        lay = layouter.place(inst, x=x_rightrow, y=y_tie, rotation=rot_rightrow)
        nwmbb1 = lay.bounds(mask=nwm.mask)
        lipindvssbb1 = lay.bounds(mask=lipin.mask, net=dvss, depth=1)
        lipindvddbb1 = lay.bounds(mask=lipin.mask, net=dvdd, depth=1)

        inst = ckt.instantiate(tie_cell, name="urtie")
        dvss.childports += inst.ports.vss
        dvdd.childports += inst.ports.vdd

        y_tie = _frm.boundary.top - dbound - _tie_rotbb.top
        lay = layouter.place(inst, x=x_rightrow, y=y_tie, rotation=rot_rightrow)
        nwmbb2 = lay.bounds(mask=nwm.mask)
        lipindvssbb2 = lay.bounds(mask=lipin.mask, net=dvss, depth=1)
        lipindvddbb2 = lay.bounds(mask=lipin.mask, net=dvdd, depth=1)

        shape = _geo.Rect.from_rect(rect=nwmbb1, top=nwmbb2.top)
        layouter.add_wire(net=dvdd, wire=nwm, shape=shape)

        shape = _geo.Rect.from_rect(rect=lipindvssbb1, top=lipindvssbb2.top)
        layouter.add_wire(net=dvss, wire=li, shape=shape)
        w = tech.on_grid(shape.width, mult=2, rounding="floor")
        h = tech.on_grid(shape.height, mult=2, rounding="floor")
        o = tech.on_grid(shape.center)
        lay = layouter.add_wire(
            net=dvss, wire=mcon, origin=o, bottom_width=w, bottom_height=h,
        )
        dvss_rightrowm1bb = lay.bounds(mask=m1.mask)

        assert dvss_rightrowm1bb.center.x < dvss_bb.center.x, "Internal error"
        w = tech.on_grid(dvss_rightrowm1bb.width, mult=2, rounding="floor")
        h = tech.on_grid(dvss_bb.height, mult=2, rounding="floor")
        x_via = tech.on_grid(dvss_rightrowm1bb.center.x)
        y_via = tech.on_grid(dvss_bb.center.y)
        layouter.add_wire(
            net=dvss, wire=via, x=x_via, y=y_via,
            bottom_width=w, bottom_height=h, top_width=w, top_height=h,
        )
        via2_lay = layouter.add_wire(
            net=dvss, wire=via2, x=x_via, y=y_via,
            bottom_width=w, bottom_height=h, top_width=w, top_height=h,
        )
        via2_m3bb = via2_lay.bounds(mask=m3.mask)

        shape = _geo.Rect.from_rect(rect=dvss_bb, left=via2_m3bb.left)
        layouter.add_wire(net=dvss, wire=m3, shape=shape)

        layouter.add_wire(net=dvss, wire=m3, pin=m3pin, shape=dvss_bb)

        shape = _geo.Rect.from_rect(rect=lipindvddbb1, top=lipindvddbb2.top)
        layouter.add_wire(net=dvdd, wire=li, shape=shape)
        w = tech.on_grid(shape.width, mult=2, rounding="floor")
        h = tech.on_grid(shape.height, mult=2, rounding="floor")
        o = tech.on_grid(shape.center)
        lay = layouter.add_wire(
            net=dvdd, wire=mcon, origin=o, bottom_width=w, bottom_height=h,
        )
        dvdd_rightrowm1bb = lay.bounds(mask=m1.mask)

        assert dvdd_rightrowm1bb.center.x < dvdd_bb.center.x, "Internal error"
        w = tech.on_grid(dvdd_rightrowm1bb.width, mult=2, rounding="floor")
        h = tech.on_grid(dvdd_bb.height, mult=2, rounding="floor")
        x_via = tech.on_grid(dvdd_rightrowm1bb.center.x)
        y_via = tech.on_grid(dvdd_bb.center.y)
        layouter.add_wire(
            net=dvdd, wire=via, x=x_via, y=y_via,
            bottom_width=w, bottom_height=h, top_width=w, top_height=h,
        )
        via2_lay = layouter.add_wire(
            net=dvdd, wire=via2, x=x_via, y=y_via,
            bottom_width=w, bottom_height=h, top_width=w, top_height=h,
        )
        via2_m3bb = via2_lay.bounds(mask=m3.mask)

        shape = _geo.Rect.from_rect(rect=dvdd_bb, left=via2_m3bb.left)
        lay = layouter.add_wire(net=dvdd, wire=m3, shape=shape)

        layouter.add_wire(net=dvdd, wire=m3, pin=m3pin, shape=dvdd_bb)

        # below SRAM
        rot_midrow = _geo.Rotation.R0
        _tie_rotbb = rot_midrow*_tie_bb

        y_midrow = sram_bb.bottom - dbound - _tie_rotbb.top

        inst = ckt.instantiate(tie_cell, name="mltie")
        dvss.childports += inst.ports.vss
        dvdd.childports += inst.ports.vdd

        x_tie = sram_bb.left - _tie_rotbb.left
        lay = layouter.place(inst, x=x_tie, y=y_midrow, rotation=rot_midrow)
        nwmbb1 = lay.bounds(mask=nwm.mask)
        lipindvssbb1 = lay.bounds(mask=lipin.mask, net=dvss, depth=1)
        lipindvddbb1 = lay.bounds(mask=lipin.mask, net=dvdd, depth=1)

        inst = ckt.instantiate(tie_cell, name="mrtie")
        dvss.childports += inst.ports.vss
        dvdd.childports += inst.ports.vdd

        x_tie = sram_bb.right - _tie_rotbb.right
        lay = layouter.place(inst, x=x_tie, y=y_midrow, rotation=rot_midrow)
        nwmbb2 = lay.bounds(mask=nwm.mask)
        lipindvssbb2 = lay.bounds(mask=lipin.mask, net=dvss, depth=1)
        lipindvddbb2 = lay.bounds(mask=lipin.mask, net=dvdd, depth=1)

        shape = _geo.Rect.from_rect(rect=nwmbb1, right=nwmbb2.right)
        layouter.add_wire(net=dvdd, wire=nwm, shape=shape)

        shape = _geo.Rect.from_rect(rect=lipindvssbb1, right=lipindvssbb2.right)
        layouter.add_wire(net=dvss, wire=li, shape=shape)
        w = tech.on_grid(shape.width, mult=2, rounding="floor")
        h = tech.on_grid(shape.height, mult=2, rounding="floor")
        o = tech.on_grid(shape.center)
        lay = layouter.add_wire(
            net=dvss, wire=mcon, origin=o, bottom_width=w, bottom_height=h,
        )
        dvss_midrowm1bb = lay.bounds(mask=m1.mask)

        shape = _geo.Rect.from_rect(rect=lipindvddbb1, right=lipindvddbb2.right)
        layouter.add_wire(net=dvdd, wire=li, shape=shape)
        w = tech.on_grid(shape.width, mult=2, rounding="floor")
        h = tech.on_grid(shape.height, mult=2, rounding="floor")
        o = tech.on_grid(shape.center)
        lay = layouter.add_wire(
            net=dvdd, wire=mcon, origin=o, bottom_width=w, bottom_height=h,
        )
        dvdd_midrowm1bb = lay.bounds(mask=m1.mask)

        assert dvss_leftrowm1bb.center.x > dvdd_leftrowm1bb.center.x, "Internal error"
        assert dvss_rightrowm1bb.center.x > dvdd_rightrowm1bb.center.x, "Internal error"

        shape = _geo.Rect.from_rect(
            rect=dvss_midrowm1bb,
            left=dvss_leftrowm1bb.left, right=dvdd_rightrowm1bb.left - 1.0,
        )
        layouter.add_wire(net=dvss, wire=m1, shape=shape)

        w = shape.height
        _via_lay = layouter.wire_layout(
            net=dvss, wire=via, bottom_width=w, bottom_height=w,
        )
        _via_m1bb = _via_lay.bounds(mask=m1.mask)

        y_via = shape.center.y
        x_via = shape.right - _via_m1bb.right
        lay = layouter.place(_via_lay, x=x_via, y=y_via)
        m2bb1 = lay.bounds(mask=m2.mask)
        x_via = dvss_rightrowm1bb.center.x
        lay = layouter.place(_via_lay, x=x_via, y=y_via)
        m2bb2 = lay.bounds(mask=m2.mask)

        shape = _geo.Rect.from_rect(rect=m2bb1, right=m2bb2.right)
        layouter.add_wire(net=dvss, wire=m2, shape=shape)

        shape = _geo.Rect.from_rect(
            rect=dvdd_midrowm1bb,
            left=(dvss_leftrowm1bb.right + 1.0), right=dvdd_rightrowm1bb.right,
        )
        layouter.add_wire(net=dvdd, wire=m1, shape=shape)

        w = shape.height
        _via_lay = layouter.wire_layout(
            net=dvdd, wire=via, bottom_width=w, bottom_height=w,
        )
        _via_m1bb = _via_lay.bounds(mask=m1.mask)

        y_via = shape.center.y
        x_via = shape.left - _via_m1bb.left
        lay = layouter.place(_via_lay, x=x_via, y=y_via)
        m2bb1 = lay.bounds(mask=m2.mask)
        x_via = dvdd_leftrowm1bb.center.x
        lay = layouter.place(_via_lay, x=x_via, y=y_via)
        m2bb2 = lay.bounds(mask=m2.mask)

        shape = _geo.Rect.from_rect(rect=m2bb1, left=m2bb2.left)
        layouter.add_wire(net=dvdd, wire=m2, shape=shape)

        # Connect the SRAM signals
        #
        # vss
        spec = io_sig2spec["vss"]
        sram_port = sram.ports[spec.sram_signal]
        net = ckt.new_net(name=spec.toppin_name, external=True, childports=sram_port)
        toppin_bb = _frm.toppins[spec.toppin_name]
        bbs = tuple(ms.shape.bounds for ms in sram_lay.filter_polygons(
            net=net, mask=m2pin.mask, depth=1, split=True,
        ))
        left = max(bb.left for bb in bbs)
        top = max(bb.top for bb in bbs)
        bottom = min(bb.bottom for bb in bbs)
        w = 10.0
        x_via2 = left + w/2.0
        right = left + w

        for bb in bbs:
            y_via2 = bb.center.y
            layouter.add_wire(
                net=net, wire=via2, x=x_via2, y=y_via2,
                bottom_width=w, bottom_enclosure="wide",
                top_width=w, top_enclosure="wide",
            )

        shape = _geo.Rect(
            left=left, bottom=bottom, right=right, top=(top + 20.0),
        )
        layouter.add_wire(net=net, wire=m3, shape=shape)
        shape = _geo.Rect(
            left=toppin_bb.left, bottom=(top + 10.0), right=right, top=(top+20.0),
        )
        layouter.add_wire(net=net, wire=m3, shape=shape)
        shape = _geo.Rect.from_rect(rect=toppin_bb, bottom=(top + 10.0))
        layouter.add_wire(net=net, wire=m3, shape=shape)
        layouter.add_wire(net=net, wire=m3, pin=m3pin, shape=toppin_bb)

        # io_clamp_low
        clamp_bb = _frm.toppins["io_clamp_low[1]"]
        shape = _geo.Rect.from_rect(rect=clamp_bb, bottom=(top + 10))
        layouter.add_wire(net=net, wire=m3, shape=shape)

        # vdd
        spec = io_sig2spec["vdd"]
        sram_port = sram.ports[spec.sram_signal]
        net = ckt.new_net(name=spec.toppin_name, external=True, childports=sram_port)
        toppin_bb = _frm.toppins[spec.toppin_name]
        bbs = tuple(ms.shape.bounds for ms in sram_lay.filter_polygons(
            net=net, mask=m2pin.mask, depth=1, split=True,
        ))
        right = min(bb.right for bb in bbs)
        top = max(bb.top for bb in bbs)
        bottom = min(bb.bottom for bb in bbs)
        w = 10.0
        x_via2 = right - w/2.0
        left = right - w

        for bb in bbs:
            y_via2 = bb.center.y
            layouter.add_wire(
                net=net, wire=via2, x=x_via2, y=y_via2,
                bottom_width=w, bottom_enclosure="wide",
                top_width=w, top_enclosure="wide",
            )

        shape = _geo.Rect(
            left=left, bottom=bottom, right=right, top=(top + 20.0),
        )
        layouter.add_wire(net=net, wire=m3, shape=shape)
        shape = _geo.Rect(
            left=left, bottom=(top + 10.0), right=toppin_bb.right, top=(top + 20.0),
        )
        layouter.add_wire(net=net, wire=m3, shape=shape)
        shape = _geo.Rect.from_rect(rect=toppin_bb, bottom=(top + 10.0))
        layouter.add_wire(net=net, wire=m3, shape=shape)
        layouter.add_wire(net=net, wire=m3, pin=m3pin, shape=toppin_bb)

        # io_clamp_high
        clamp_bb = _frm.toppins["io_clamp_high[1]"]
        w = clamp_bb.width
        shape = _geo.Rect.from_rect(rect=clamp_bb, bottom=(clamp_bb.bottom - 2*w))
        layouter.add_wire(net=net, wire=m3, shape=shape)
        shape = _geo.Rect(
            left=clamp_bb.left, bottom=(clamp_bb.bottom - 2*w),
            right=toppin_bb.right, top=(clamp_bb.bottom - w)
        )
        layouter.add_wire(net=net, wire=m3, shape=shape)

        # connect the input signals
        a_col = 0
        for sig_name in (
            *(f"a[{a_bit}]" for a_bit in reversed(range(self.a_bits))), # Reversed for a_col
            "clk", "we[0]",
            *(f"d[{bit}]" for bit in range(self.word_size)),
        ):
            spec = io_sig2spec[sig_name]
            prefix = spec.prefix
            num = spec.io_number

            pin_name = spec.toppin_name
            oeb_name = f"io_oeb[{num}]"
            out_name = f"io_out[{num}]"
            assert spec.io_type == "io_in", "Internal error"
            assert spec.oeb, "Internal error"
            sram_port = sram.ports[sig_name]

            # instantiate cells
            buf = ckt.instantiate(buf_cell, name="{prefix}buf")
            one = ckt.instantiate(one_cell, name=f"{prefix}one")
            zero = ckt.instantiate(zero_cell, name=f"{prefix}zero")
            tie = ckt.instantiate(tie_cell, name=f"{prefix}tie")

            # create nets
            pin_net = ckt.new_net(name=pin_name, external=True, childports=buf.ports.i)
            sig_net = ckt.new_net(name=sig_name, external=False, childports=(
                buf.ports.q, sram_port,
            ))
            oeb_net = ckt.new_net(
                name=oeb_name, external=True, childports=one.ports.one,
            )
            out_net = ckt.new_net(
                name=out_name, external=True, childports=zero.ports.zero,
            )

            # get bbs; SRAM m2 pin to m3 pin
            toppin_bb = _frm.toppins[pin_name]
            oeb_bb = _frm.toppins[oeb_name]
            out_bb = _frm.toppins[out_name]
            if sig_name.startswith("a["):
                # Connect signal up to m2
                sram_m1pinbb = sram_lay.bounds(mask=m1pin.mask, net=sig_net, depth=1)

                w = 10.0
                right = sram_bb.left - (2*a_col + 1)*w
                left = right - 1
                a_col += 1

                x_via = right - w/2.0
                y_via = tech.on_grid(sram_m1pinbb.center.y)
                via_lay = layouter.add_wire(
                    net=sig_net, wire=via, x=x_via, y=y_via,
                    bottom_width=w, bottom_enclosure="wide",
                    top_width=w, top_enclosure="wide",
                )
                via_m1bb = via_lay.bounds(mask=m1.mask)
                sram_m2pinbb = via_lay.bounds(mask=m2.mask)

                shape = _geo.Rect.from_rect(rect=sram_m1pinbb, left=via_m1bb.left)
                layouter.add_wire(net=sig_net, wire=m1, shape=shape)
            else:
                sram_m2pinbb = sram_lay.bounds(mask=m2pin.mask, net=sig_net, depth=1)
            is_leftrow = toppin_bb.center.x < sram_m2pinbb.center.x

            rot = rot_leftrow if is_leftrow else rot_rightrow
            x_row = x_leftrow if is_leftrow else x_rightrow

            # place buf
            _buf_rotilipinbb = rot*_buf_ilipinbb
            y_buf = tech.on_grid(
                toppin_bb.top - _buf_rotilipinbb.bottom,
                mult=2,
            )
            buf_lay = layouter.place(buf, x=x_row, y=y_buf, rotation=rot)
            pinbuf_lipinbb = buf_lay.bounds(mask=lipin.mask, net=pin_net, depth=1)
            sigbuf_lipinbb = buf_lay.bounds(mask=lipin.mask, net=sig_net, depth=1)
            buf_bb = buf_lay.boundary
            assert buf_bb is not None

            # place tie cell
            _tie_rotbb = rot*_tie_bb
            if is_leftrow:
                y_tie = buf_bb.top - _tie_rotbb.bottom
            else:
                y_tie = buf_bb.bottom - _tie_rotbb.top
            layouter.place(tie, x=x_row, y=y_tie, rotation=rot)

            # place zero cell
            _zero_rotbb = rot*_zero_bb
            if is_leftrow:
                y_zero = buf_bb.bottom - _zero_rotbb.top
            else:
                y_zero = buf_bb.top - _zero_rotbb.bottom
            zero_lay = layouter.place(zero, x=x_row, y=y_zero, rotation=rot)
            zero_bb = zero_lay.boundary
            assert zero_bb is not None
            zeroout_lipinbb = zero_lay.bounds(mask=lipin.mask, net=out_net, depth=1)

            # place one cell
            _one_rotbb = rot*_one_bb
            if is_leftrow:
                y_one = zero_bb.bottom - _one_rotbb.top
            else:
                y_one = zero_bb.top - _one_rotbb.bottom
            one_lay = layouter.place(one, x=x_row, y=y_one, rotation=rot)
            oneoeb_lipinbb = one_lay.bounds(mask=lipin.mask, net=oeb_net, depth=1)

            # connect pin_net
            w = tech.on_grid(pinbuf_lipinbb.width, mult=2, rounding="floor")
            o_via = tech.on_grid(pinbuf_lipinbb.center)
            layouter.add_wire(
                net=pin_net, wire=mcon, origin=o_via,
                bottom_width=w, bottom_enclosure="wide",
                top_width=w, top_enclosure="wide",
            )
            layouter.add_wire(
                net=pin_net, wire=via, origin=o_via,
                bottom_width=w, bottom_enclosure="wide",
                top_width=w, top_enclosure="wide",
            )
            via2_lay = layouter.add_wire(
                net=pin_net, wire=via2, origin=o_via,
                bottom_width=w, bottom_enclosure="wide",
                top_width=w, top_enclosure="wide",
            )
            via2_m3bb = via2_lay.bounds(mask=m3.mask)

            if is_leftrow:
                shape = _geo.Rect.from_rect(rect=toppin_bb, right=via2_m3bb.right)
            else:
                shape = _geo.Rect.from_rect(rect=toppin_bb, left=via2_m3bb.left)
            layouter.add_wire(net=pin_net, wire=m3, shape=shape)
            layouter.add_wire(net=pin_net, wire=m3, pin=m3pin, shape=toppin_bb)

            # connect sig_net
            w = tech.on_grid(sigbuf_lipinbb.width, mult=2, rounding="floor")
            o_via = tech.on_grid(sigbuf_lipinbb.center)
            layouter.add_wire(
                net=sig_net, wire=mcon, origin=o_via,
                bottom_width=w, bottom_enclosure="wide",
                top_width=w, top_enclosure="wide",
            )
            layouter.add_wire(
                net=sig_net, wire=via, origin=o_via,
                bottom_width=w, bottom_enclosure="wide",
                top_width=w, top_enclosure="wide",
            )
            via2_lay = layouter.add_wire(
                net=sig_net, wire=via2, origin=o_via,
                bottom_width=w, bottom_enclosure="wide",
                top_width=w, top_enclosure="wide",
            )
            via2_m3bb1 = via2_lay.bounds(mask=m3.mask)

            _via2_lay = layouter.wire_layout(
                net=sig_net, wire=via2, rows=6, columns=3,
            )
            _via2_m2bb = _via2_lay.bounds(mask=m2.mask)
            if is_leftrow:
                x_via2 = sram_m2pinbb.right - _via2_m2bb.right
            else:
                x_via2 = sram_m2pinbb.left - _via2_m2bb.left
            y_via2 = via2_m3bb1.center.y
            via2_lay = layouter.place(_via2_lay, x=x_via2, y=y_via2)
            via2_m2bb = via2_lay.bounds(mask=m2.mask)
            via2_m3bb2 = via2_lay.bounds(mask=m3.mask)

            shape = _geo.Rect.from_rect(rect=sram_m2pinbb, bottom=via2_m2bb.bottom)
            layouter.add_wire(net=sig_net, wire=m2, shape=shape)
            if is_leftrow:
                shape = _geo.Rect.from_rect(rect=via2_m3bb1, right=via2_m3bb2.right)
            else:
                shape = _geo.Rect.from_rect(rect=via2_m3bb1, left=via2_m3bb2.left)
            layouter.add_wire(net=sig_net, wire=m3, shape=shape)

            # connect oeb_net
            w = tech.on_grid(oneoeb_lipinbb.width, mult=2, rounding="floor")
            o_via = tech.on_grid(oneoeb_lipinbb.center)
            layouter.add_wire(
                net=oeb_net, wire=mcon, origin=o_via,
                bottom_width=w, bottom_enclosure="wide",
                top_width=w, top_enclosure="wide",
            )
            via_lay = layouter.add_wire(
                net=oeb_net, wire=via, origin=o_via,
                bottom_width=w, bottom_enclosure="wide",
                top_width=w, top_enclosure="wide",
            )
            via_m2bb = via_lay.bounds(mask=m2.mask)

            o_via2 = _geo.Point.from_point(point=o_via, y=oeb_bb.center.y)
            via2_lay = layouter.add_wire(
                net=oeb_net, wire=via2, origin=o_via2,
                bottom_width=w, bottom_enclosure="wide",
                top_width=w, top_enclosure="wide",
            )
            via2_m2bb = via2_lay.bounds(mask=m2.mask)
            via2_m3bb = via2_lay.bounds(mask=m3.mask)

            if is_leftrow:
                shape = _geo.Rect.from_rect(rect=via_m2bb, bottom=via2_m2bb.bottom)
            else:
                shape = _geo.Rect.from_rect(rect=via_m2bb, top=via2_m2bb.top)
            layouter.add_wire(net=oeb_net, wire=m2, shape=shape)
            if is_leftrow:
                shape = _geo.Rect.from_rect(rect=oeb_bb, right=via2_m3bb.right)
            else:
                shape = _geo.Rect.from_rect(rect=oeb_bb, left=via2_m3bb.left)
            layouter.add_wire(net=oeb_net, wire=m3, shape=shape)

            layouter.add_wire(net=oeb_net, wire=m3, pin=m3pin, shape=oeb_bb)

            # connect out_net
            w = tech.on_grid(zeroout_lipinbb.width, mult=2, rounding="floor")
            o_via = tech.on_grid(zeroout_lipinbb.center)
            layouter.add_wire(
                net=out_net, wire=mcon, origin=o_via,
                bottom_width=w, bottom_enclosure="wide",
                top_width=w, top_enclosure="wide",
            )
            layouter.add_wire(
                net=out_net, wire=via, origin=o_via,
                bottom_width=w, bottom_enclosure="wide",
                top_width=w, top_enclosure="wide",
            )
            via2_lay = layouter.add_wire(
                net=out_net, wire=via2, origin=o_via,
                bottom_width=w, bottom_enclosure="wide",
                top_width=w, top_enclosure="wide",
            )
            via2_m3bb = via2_lay.bounds(mask=m3.mask)

            if is_leftrow:
                shape = _geo.Rect.from_rect(rect=via2_m3bb, bottom=out_bb.bottom)
            else:
                shape = _geo.Rect.from_rect(rect=via2_m3bb, top=out_bb.top)
            layouter.add_wire(net=out_net, wire=m3, shape=shape)
            if is_leftrow:
                shape = _geo.Rect.from_rect(rect=out_bb, right=via2_m3bb.right)
            else:
                shape = _geo.Rect.from_rect(rect=out_bb, left=via2_m3bb.left)
            layouter.add_wire(net=out_net, wire=m3, shape=shape)

            layouter.add_wire(net=out_net, wire=m3, pin=m3pin, shape=out_bb)

        # connect the output signals
        for sig_name in (
            *(f"q[{bit}]" for bit in range(self.word_size)),
        ):
            spec = io_sig2spec[sig_name]
            prefix = spec.prefix
            num = spec.io_number

            pin_name = spec.toppin_name
            oeb_name = f"io_oeb[{num}]"
            assert spec.io_type == "io_out", "Internal error"
            assert not spec.oeb, "Internal error"
            sram_port = sram.ports[spec.sram_signal]

            # instantiate cells
            buf = ckt.instantiate(buf_cell, name="{prefix}buf")
            zero = ckt.instantiate(zero_cell, name=f"{prefix}zero")
            tie = ckt.instantiate(tie_cell, name=f"{prefix}tie")

            # create nets
            pin_net = ckt.new_net(name=pin_name, external=True, childports=buf.ports.q)
            sig_net = ckt.new_net(name=sig_name, external=False, childports=(
                buf.ports.i, sram_port,
            ))
            oeb_net = ckt.new_net(
                name=oeb_name, external=True, childports=zero.ports.zero,
            )

            # get bss
            toppin_bb = _frm.toppins[pin_name]
            oeb_bb = _frm.toppins[oeb_name]
            sram_m2pinbb = sram_lay.bounds(mask=m2pin.mask, net=sig_net, depth=1)

            is_leftrow = toppin_bb.center.x < sram_m2pinbb.center.x

            # place buf
            rot = rot_midrow
            y_row = y_midrow
            _buf_rotilipinbb = rot*_buf_ilipinbb
            x_buf = tech.on_grid(
                sram_m2pinbb.right - _buf_rotilipinbb.left,
                mult=2, rounding="ceiling",
            )
            buf_lay = layouter.place(buf, x=x_buf, y=y_row, rotation=rot)
            pinbuf_lipinbb = buf_lay.bounds(mask=lipin.mask, net=pin_net, depth=1)
            sigbuf_lipinbb = buf_lay.bounds(mask=lipin.mask, net=sig_net, depth=1)
            buf_bb = buf_lay.boundary
            assert buf_bb is not None

            # place zero
            rot = rot_leftrow if is_leftrow else rot_rightrow
            x_row = x_leftrow if is_leftrow else x_rightrow
            _zero_rotzerolipinbb = rot*_zero_zerolipinbb
            y_zero = oeb_bb.center.y - _zero_rotzerolipinbb.center.y
            zero_lay = layouter.place(zero, x=x_row, y=y_zero, rotation=rot)
            zero_zerolipinbb = zero_lay.bounds(mask=lipin.mask, net=oeb_net, depth=1)
            zero_bb = zero_lay.boundary
            assert zero_bb is not None

            # place tie
            _tie_rotbb = rot*_tie_bb
            y_tie = zero_bb.top - _tie_rotbb.bottom
            layouter.place(tie, x=x_row, y=y_tie, rotation=rot)

            # connect sig_net
            h = tech.on_grid(sigbuf_lipinbb.height, mult=2, rounding="floor")
            o_via = tech.on_grid(sigbuf_lipinbb.center)
            layouter.add_wire(
                net=sig_net, wire=mcon, origin=o_via,
                bottom_height=h, bottom_enclosure="tall",
                top_height=h, top_enclosure="tall",
            )
            via_lay = layouter.add_wire(
                net=sig_net, wire=via, origin=o_via,
                bottom_height=h, bottom_enclosure="tall",
                top_height=h, top_enclosure="tall",
            )
            via_m2bb = via_lay.bounds(mask=m2.mask)

            shape = _geo.Rect.from_rect(rect=sram_m2pinbb, bottom=via_m2bb.bottom)
            layouter.add_wire(net=sig_net, wire=m2, shape=shape)

            # connect pin_net
            h = tech.on_grid(pinbuf_lipinbb.height, mult=2, rounding="floor")
            o_via = tech.on_grid(pinbuf_lipinbb.center)

            layouter.add_wire(
                net=sig_net, wire=mcon, origin=o_via,
                bottom_height=h, bottom_enclosure="tall",
                top_height=h, top_enclosure="tall",
            )
            via_lay = layouter.add_wire(
                net=sig_net, wire=via, origin=o_via,
                bottom_height=h, bottom_enclosure="tall",
                top_height=h, top_enclosure="tall",
            )
            via_m2bb = via_lay.bounds(mask=m2.mask)

            _via2_lay = layouter.wire_layout(
                net=pin_net, wire=via2, rows=6, columns=3,
            )
            _via2_m2bb = _via2_lay.bounds(mask=m2.mask)
            if is_leftrow:
                x_via2 = via_m2bb.right - _via2_m2bb.right
            else:
                x_via2 = via_m2bb.left - _via2_m2bb.left
            y_via2 = toppin_bb.center.y
            via2_lay = layouter.place(_via2_lay, x=x_via2, y=y_via2)
            via2_m2bb = via2_lay.bounds(mask=m2.mask)
            via2_m3bb = via2_lay.bounds(mask=m3.mask)

            shape = _geo.Rect.from_rect(rect=via_m2bb, bottom=via2_m2bb.bottom)
            layouter.add_wire(net=pin_net, wire=m2, shape=shape)
            if is_leftrow:
                shape = _geo.Rect.from_rect(rect=toppin_bb, right=via2_m3bb.right)
            else:
                shape = _geo.Rect.from_rect(rect=toppin_bb, left=via2_m3bb.left)
            layouter.add_wire(net=pin_net, wire=m3, shape=shape)
            layouter.add_wire(net=pin_net, wire=m3, pin=m3pin, shape=toppin_bb)

            # connect oeb_net
            w = tech.on_grid(zero_zerolipinbb.width, mult=2, rounding="floor")
            o_via = tech.on_grid(zero_zerolipinbb.center)
            layouter.add_wire(
                net=oeb_net, wire=mcon, origin=o_via,
                bottom_width=w, bottom_enclosure="wide",
                top_width=w, top_enclosure="wide",
            )
            layouter.add_wire(
                net=oeb_net, wire=via, origin=o_via,
                bottom_width=w, bottom_enclosure="wide",
                top_width=w, top_enclosure="wide",
            )
            via2_lay = layouter.add_wire(
                net=oeb_net, wire=via2, origin=o_via,
                bottom_width=w, bottom_enclosure="wide",
                top_width=w, top_enclosure="wide",
            )
            via2_m3bb = via2_lay.bounds(mask=m3.mask)

            if is_leftrow:
                shape = _geo.Rect.from_rect(rect=oeb_bb, right=via2_m3bb.right)
            else:
                shape = _geo.Rect.from_rect(rect=oeb_bb, left=via2_m3bb.left)
            layouter.add_wire(net=oeb_net, wire=m3, shape=shape)
            layouter.add_wire(net=oeb_net, wire=m3, pin=m3pin, shape=oeb_bb)

        # boundary
        #
        layout.boundary = _frm.boundary