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58 lines
1.5 KiB
Python
58 lines
1.5 KiB
Python
from amaranth import *
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from amaranth.asserts import *
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from .. import pfv
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__all__ = ["CRCheck"]
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class CRCheck(Elaboratable):
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"""Condition Register check.
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Checks that reads from CR fields are consistent with the last value that was written to them.
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"""
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def __init__(self):
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self.pre = Signal()
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self.post = Signal()
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self.pfv = pfv.Interface()
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def elaborate(self, platform):
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m = Module()
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spec_order = AnyConst(self.pfv.order.width)
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cr = Array(Record([
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("written", 1),
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("shadow", 4),
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], name=f"cr{i}") for i in range(8))
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cr_written_any = 0
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with m.If(self.pfv.stb & (self.pfv.order <= spec_order)):
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for i, cr_field in enumerate(cr):
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pfv_cr_field = getattr(self.pfv, f"cr{i}")
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with m.If(pfv_cr_field.w_stb):
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m.d.sync += [
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cr_field.written.eq(1),
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cr_field.shadow .eq(pfv_cr_field.w_data),
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]
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cr_written_any |= cr_field.written
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with m.If(self.post):
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m.d.sync += [
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Assume(Past(self.pfv.stb)),
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Assume(Past(self.pfv.order) == spec_order),
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Assume(cr_written_any),
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]
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for i, cr_field in enumerate(cr):
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pfv_cr_field = getattr(self.pfv, f"cr{i}")
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with m.If(Past(pfv_cr_field.r_stb)):
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m.d.sync += Assert(Past(pfv_cr_field.r_data) == Past(cr_field.shadow))
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return m
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