mirror of https://github.com/VLSIDA/OpenRAM.git
70 lines
2.7 KiB
Python
70 lines
2.7 KiB
Python
from tech import drc
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import debug
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import design
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from vector import vector
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from hierarchical_predecode import hierarchical_predecode
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class hierarchical_predecode3x8(hierarchical_predecode):
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"""
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Pre 3x8 decoder used in hierarchical_decoder.
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"""
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def __init__(self):
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hierarchical_predecode.__init__(self, 3)
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self.add_pins()
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self.create_modules()
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self.setup_constraints()
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self.create_layout()
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self.DRC_LVS()
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def create_layout(self):
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""" The general organization is from left to right:
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1) a set of M2 rails for input signals
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2) a set of inverters to invert input signals
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3) a set of M2 rails for the vdd, gnd, inverted inputs, inputs
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4) a set of NAND gates for inversion
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"""
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self.create_rails()
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self.add_input_inverters()
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self.add_output_inverters()
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connections=[["in[0]", "in[1]", "in[2]", "Z[7]", "vdd", "gnd"],
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["in[0]", "in[1]", "inbar[2]", "Z[6]", "vdd", "gnd"],
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["in[0]", "inbar[1]", "in[2]", "Z[5]", "vdd", "gnd"],
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["in[0]", "inbar[1]", "inbar[2]", "Z[4]", "vdd", "gnd"],
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["inbar[0]", "in[1]", "in[2]", "Z[3]", "vdd", "gnd"],
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["inbar[0]", "in[1]", "inbar[2]", "Z[2]", "vdd", "gnd"],
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["inbar[0]", "inbar[1]", "in[2]", "Z[1]", "vdd", "gnd"],
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["inbar[0]", "inbar[1]", "inbar[2]", "Z[0]", "vdd", "gnd"]]
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self.add_nand(connections)
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self.route()
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def get_nand_input_line_combination(self):
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""" These are the decoder connections of the NAND gates to the A,B,C pins """
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combination = [["Abar[0]", "Abar[1]", "Abar[2]"],
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["Abar[0]", "Abar[1]", "A[2]"],
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["Abar[0]", "A[1]", "Abar[2]"],
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["Abar[0]", "A[1]", "A[2]"],
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["A[0]", "Abar[1]", "Abar[2]"],
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["A[0]", "Abar[1]", "A[2]"],
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["A[0]", "A[1]", "Abar[2]"],
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["A[0]", "A[1]", "A[2]"]]
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return combination
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def delay(self, slew, load = 0.0 ):
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# A -> Abar
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a_t_b_delay = self.inv.delay(slew=slew,load = self.nand.input_load())
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# Abar -> z
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b_t_z_delay = self.nand.delay(slew=a_t_b_delay.slew,load = self.inv.input_load())
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result = a_t_b_delay + b_t_z_delay
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# Z -> out
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a_t_out_delay = self.inv.delay(slew=b_t_z_delay.slew,load = load)
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result = result + a_t_out_delay
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return result
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def input_load(self):
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return self.nand.input_load()
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