39 lines
1.0 KiB
Python
39 lines
1.0 KiB
Python
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from fractions import Fraction
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from migen.fhdl.structure import *
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class Inst:
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def __init__(self, infreq, outfreq):
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declare_signal(self, "clkin")
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declare_signal(self, "clkout")
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ratio = Fraction(outfreq)/Fraction(infreq)
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appr = ratio.limit_denominator(32)
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m = appr.numerator
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if m < 2 or m > 32:
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raise OverflowError
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d = appr.denominator
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in_period = float(Fraction(1000000000)/Fraction(infreq))
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self._inst = Instance("DCM_SP",
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[("CLKFX", self.clkout)],
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[("CLKIN", self.clkin),
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("PSEN", BV(1)),
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("RST", BV(1))],
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[("CLKDV_DIVIDE", 2.0),
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("CLKFX_DIVIDE", d),
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("CLKFX_MULTIPLY", m),
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("CLKIN_DIVIDE_BY_2", "FALSE"),
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("CLKIN_PERIOD", in_period),
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("CLKOUT_PHASE_SHIFT", "NONE"),
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("CLK_FEEDBACK", "NONE"),
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("DESKEW_ADJUST", "SYSTEM_SYNCHRONOUS"),
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("DUTY_CYCLE_CORRECTION", "TRUE"),
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("PHASE_SHIFT", 0),
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("STARTUP_WAIT", "TRUE")]
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)
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def get_fragment(self):
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return Fragment([self._inst.ins["PSEN"].eq(0), self._inst.ins["RST"].eq(0)], instances=[self._inst])
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