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71 lines
2.4 KiB
Python
71 lines
2.4 KiB
Python
2 years ago
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from amaranth import *
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from amaranth.asserts import *
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from power_fv.check import PowerFVCheck
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from power_fv.check._timer import Timer
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__all__ = ["CausalityCheck"]
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class CausalityCheck(PowerFVCheck, name=("causal",)):
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"""Causal consistency check.
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Checks that an instruction that writes to a GPR has completed before any subsequent
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instruction (by program order) can read it.
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"""
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def testbench(self):
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return CausalityTestbench(self)
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class CausalityTestbench(Elaboratable):
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def __init__(self, check):
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if not isinstance(check, CausalityCheck):
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raise TypeError("Check must be an instance of CausalityCheck, not {!r}"
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.format(check))
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self.check = check
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self.name = "causal_tb"
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def elaborate(self, platform):
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m = Module()
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m.submodules.t_post = t_post = Timer(self.check.depth - 1)
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m.submodules.dut = dut = self.check.dut
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write_order = AnyConst(dut.pfv.order.shape())
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write_index = AnyConst(unsigned(5))
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read_before = Signal()
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gpr_write = Record([("ra", 1), ("rb", 1), ("rs", 1), ("rt", 1)])
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gpr_read = Record.like(gpr_write)
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m.d.comb += [
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gpr_write.ra.eq(dut.pfv.ra.w_stb & (dut.pfv.ra.index == write_index)),
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gpr_write.rb.eq(dut.pfv.rb.w_stb & (dut.pfv.rb.index == write_index)),
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gpr_write.rs.eq(dut.pfv.rs.w_stb & (dut.pfv.rs.index == write_index)),
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gpr_write.rt.eq(dut.pfv.rt.w_stb & (dut.pfv.rt.index == write_index)),
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gpr_read .ra.eq(dut.pfv.ra.r_stb & (dut.pfv.ra.index == write_index)),
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gpr_read .rb.eq(dut.pfv.rb.r_stb & (dut.pfv.rb.index == write_index)),
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gpr_read .rs.eq(dut.pfv.rs.r_stb & (dut.pfv.rs.index == write_index)),
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gpr_read .rt.eq(dut.pfv.rt.r_stb & (dut.pfv.rt.index == write_index)),
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]
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with m.If(dut.pfv.stb & (dut.pfv.order > write_order) & ~dut.pfv.skip):
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with m.If(gpr_read.any()):
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m.d.sync += read_before.eq(1)
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with m.If(t_post.zero):
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m.d.comb += [
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Assume(dut.pfv.stb),
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Assume(dut.pfv.order == write_order),
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Assume(~dut.pfv.skip),
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Assume(gpr_write.any()),
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Assert(~read_before),
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]
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m.d.comb += Assert(~Past(t_post.zero))
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return m
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