50 lines
1.2 KiB
Python
50 lines
1.2 KiB
Python
from migen.fhdl.std import *
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from migen.bank.description import *
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from migen.bank.eventmanager import *
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from migen.genlib.misc import Counter
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class Timer(Module, AutoCSR):
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def __init__(self, width=32, prescaler_width=32):
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self._load = CSRStorage(width)
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self._reload = CSRStorage(width)
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self._en = CSRStorage()
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self._prescaler = CSRStorage(prescaler_width, reset=1)
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self._update_value = CSR()
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self._value = CSRStatus(width)
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self.submodules.ev = EventManager()
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self.ev.zero = EventSourceProcess()
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self.ev.finalize()
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###
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enable = self._en.storage
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tick = Signal()
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counter = Counter(prescaler_width)
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self.submodules += counter
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self.comb += [
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If(enable,
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tick.eq(counter.value >= (self._prescaler.storage-1)),
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counter.ce.eq(1),
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counter.reset.eq(tick),
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).Else(
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counter.reset.eq(1)
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)
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]
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value = Signal(width)
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self.sync += [
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If(enable,
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If(value == 0,
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# set reload to 0 to disable reloading
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value.eq(self._reload.storage)
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).Elif(tick,
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value.eq(value - 1)
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)
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).Else(
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value.eq(self._load.storage)
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),
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If(self._update_value.re, self._value.status.eq(value))
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]
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self.comb += self.ev.zero.trigger.eq(value != 0)
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