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86 lines
3.1 KiB
Python
86 lines
3.1 KiB
Python
from amaranth import *
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from amaranth.asserts import *
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from .. import PowerFVCheck
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from ... import pfv, tb
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__all__ = ["GPRSpec", "GPRCheck"]
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class GPRSpec(Elaboratable):
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"""GPR consistency specification.
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Checks that:
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* reads from a GPR return the last value that was written to it;
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* writes to multiple GPRs by a single instruction (e.g. load with update) do not target the
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same register.
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"""
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def __init__(self, post):
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self.pfv = pfv.Interface()
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self.post = tb.Trigger(cycle=post)
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def triggers(self):
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yield self.post
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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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spec_gpr_index = AnyConst(5)
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gpr_ra_read = Signal()
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gpr_ra_write = Signal()
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gpr_rb_read = Signal()
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gpr_rs_read = Signal()
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gpr_rt_read = Signal()
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gpr_rt_write = Signal()
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gpr_conflict = Signal()
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gpr_written = Signal()
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gpr_shadow = Signal(64)
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m.d.comb += [
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gpr_ra_read .eq(self.pfv.ra.r_stb & (self.pfv.ra.index == spec_gpr_index)),
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gpr_ra_write.eq(self.pfv.ra.w_stb & (self.pfv.ra.index == spec_gpr_index)),
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gpr_rb_read .eq(self.pfv.rb.r_stb & (self.pfv.rb.index == spec_gpr_index)),
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gpr_rs_read .eq(self.pfv.rs.r_stb & (self.pfv.rs.index == spec_gpr_index)),
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gpr_rt_read .eq(self.pfv.rt.r_stb & (self.pfv.rt.index == spec_gpr_index)),
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gpr_rt_write.eq(self.pfv.rt.w_stb & (self.pfv.rt.index == spec_gpr_index)),
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]
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with m.If(self.pfv.stb & ~self.pfv.intr & (self.pfv.order <= spec_order)):
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with m.If(gpr_ra_write & gpr_rt_write):
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m.d.sync += gpr_conflict.eq(1)
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with m.If(gpr_ra_write | gpr_rt_write):
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m.d.sync += gpr_written.eq(1)
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with m.If(gpr_ra_write):
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m.d.sync += gpr_shadow.eq(self.pfv.ra.w_data)
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with m.Else():
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m.d.sync += gpr_shadow.eq(self.pfv.rt.w_data)
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with m.If(self.post.stb):
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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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]
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with m.If(~Past(self.pfv.intr)):
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m.d.sync += Assert(gpr_written.implies(~gpr_conflict))
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with m.If(gpr_written & Past(gpr_ra_read)):
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m.d.sync += Assert(Past(gpr_shadow) == Past(self.pfv.ra.r_data))
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with m.If(gpr_written & Past(gpr_rb_read)):
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m.d.sync += Assert(Past(gpr_shadow) == Past(self.pfv.rb.r_data))
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with m.If(gpr_written & Past(gpr_rs_read)):
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m.d.sync += Assert(Past(gpr_shadow) == Past(self.pfv.rs.r_data))
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with m.If(gpr_written & Past(gpr_rt_read)):
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m.d.sync += Assert(Past(gpr_shadow) == Past(self.pfv.rt.r_data))
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return m
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class GPRCheck(PowerFVCheck, name="cons_gpr"):
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def get_testbench(self, dut, post):
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tb_spec = GPRSpec(post)
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tb_top = tb.Testbench(tb_spec, dut)
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return tb_top
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