mirror of https://github.com/VLSIDA/OpenRAM.git
168 lines
6.3 KiB
Python
168 lines
6.3 KiB
Python
# See LICENSE for licensing information.
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#
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# Copyright (c) 2016-2022 Regents of the University of California and The Board
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# of Regents for the Oklahoma Agricultural and Mechanical College
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# (acting for and on behalf of Oklahoma State University)
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# All rights reserved.
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#
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from openram import debug
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from openram.base import vector
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from openram.sram_factory import factory
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from .pgate import *
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class pdriver(pgate):
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"""
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This instantiates an even or odd number of inverters
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sized for driving a load.
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"""
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def __init__(self, name, inverting=False, fanout=0, size_list=None, height=None, add_wells=True):
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debug.info(1, "creating pdriver {}".format(name))
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self.stage_effort = 3
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self.height = height
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self.inverting = inverting
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self.size_list = size_list
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self.fanout = fanout
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if not size_list and self.fanout == 0:
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debug.error("Either fanout or size list must be specified.", -1)
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if self.size_list and self.fanout != 0:
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debug.error("Cannot specify both size_list and fanout.", -1)
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if self.size_list and self.inverting:
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debug.error("Cannot specify both size_list and inverting.", -1)
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# Creates the netlist and layout
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super().__init__(name, height, add_wells)
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def compute_sizes(self):
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# size_list specified
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if self.size_list:
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self.num_stages = len(self.size_list)
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else:
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# Find the optimal number of stages for the given effort
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self.num_stages = max(1,
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int(round(self.fanout ** (1 / self.stage_effort))))
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# Increase the number of stages if we need to fix polarity
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if self.inverting and (self.num_stages % 2 == 0):
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self.num_stages += 1
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elif not self.inverting and (self.num_stages % 2):
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self.num_stages += 1
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self.size_list = []
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# compute sizes backwards from the fanout
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fanout_prev = self.fanout
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for x in range(self.num_stages):
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fanout_prev = max(round(fanout_prev / self.stage_effort), 1)
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self.size_list.append(fanout_prev)
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# reverse the sizes to be from input to output
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self.size_list.reverse()
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def create_netlist(self):
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self.compute_sizes()
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self.add_comment("sizes: {}".format(str(self.size_list)))
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self.add_pins()
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self.add_modules()
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self.create_insts()
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def create_layout(self):
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self.place_modules()
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self.route_wires()
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self.add_layout_pins()
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self.width = self.inv_inst_list[-1].rx()
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self.height = self.inv_inst_list[0].height
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self.extend_wells()
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self.route_supply_rails()
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self.add_boundary()
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def add_pins(self):
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self.add_pin("A", "INPUT")
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self.add_pin("Z", "OUTPUT")
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self.add_pin("vdd", "POWER")
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self.add_pin("gnd", "GROUND")
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def add_modules(self):
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self.inv_list = []
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for size in self.size_list:
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temp_inv = factory.create(module_type="pinv",
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size=size,
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height=self.height,
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add_wells=self.add_wells)
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self.inv_list.append(temp_inv)
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def create_insts(self):
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self.inv_inst_list = []
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for x in range(1, self.num_stages + 1):
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# Create first inverter
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if x == 1:
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zbx_int = "Zb{}_int".format(x)
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inst = self.add_inst(name="buf_inv{}".format(x),
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mod=self.inv_list[x - 1])
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self.inv_inst_list.append(inst)
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if self.num_stages == 1:
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self.connect_inst(["A", "Z", "vdd", "gnd"])
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else:
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self.connect_inst(["A", zbx_int, "vdd", "gnd"])
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# Create last inverter
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elif x == self.num_stages:
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zbn_int = "Zb{}_int".format(x - 1)
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inst = self.add_inst(name="buf_inv{}".format(x),
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mod=self.inv_list[x - 1])
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self.inv_inst_list.append(inst)
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self.connect_inst([zbn_int, "Z", "vdd", "gnd"])
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# Create middle inverters
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else:
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zbx_int = "Zb{}_int".format(x - 1)
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zbn_int = "Zb{}_int".format(x)
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inst = self.add_inst(name="buf_inv{}".format(x),
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mod=self.inv_list[x - 1])
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self.inv_inst_list.append(inst)
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self.connect_inst([zbx_int, zbn_int, "vdd", "gnd"])
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def place_modules(self):
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# Add the first inverter at the origin
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self.inv_inst_list[0].place(vector(0, 0))
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# Add inverters to the right of the previous inverter
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for x in range(1, len(self.inv_inst_list)):
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loc = vector(self.inv_inst_list[x - 1].rx(), 0)
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self.inv_inst_list[x].place(loc)
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def route_wires(self):
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z_inst_list = []
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a_inst_list = []
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# inv_current Z to inv_next A
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for x in range(0, len(self.inv_inst_list) - 1):
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z_inst_list.append(self.inv_inst_list[x].get_pin("Z"))
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a_inst_list.append(self.inv_inst_list[x + 1].get_pin("A"))
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mid_point = vector(z_inst_list[x].cx(), a_inst_list[x].cy())
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self.add_path(self.route_layer,
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[z_inst_list[x].center(), mid_point,
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a_inst_list[x].center()])
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def add_layout_pins(self):
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z_pin = self.inv_inst_list[len(self.inv_inst_list) - 1].get_pin("Z")
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self.add_layout_pin_rect_center(text="Z",
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layer=z_pin.layer,
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offset=z_pin.center(),
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width=z_pin.width(),
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height=z_pin.height())
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a_pin = self.inv_inst_list[0].get_pin("A")
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self.add_layout_pin_rect_center(text="A",
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layer=a_pin.layer,
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offset=a_pin.center(),
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width=a_pin.width(),
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height=a_pin.height())
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def get_sizes(self):
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""" Return the relative sizes of the buffers """
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return self.size_list
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