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101 lines
3.8 KiB
Python
101 lines
3.8 KiB
Python
from amaranth import *
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from amaranth.lib.coding import Encoder
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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__ = ["GPRCheck"]
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class GPRCheck(PowerFVCheck, name=("gpr",)):
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"""GPR consistency check.
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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 conflict
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with each other.
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"""
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def testbench(self):
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return GPRTestbench(self)
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class GPRTestbench(Elaboratable):
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def __init__(self, check):
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if not isinstance(check, GPRCheck):
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raise TypeError("Check must be an instance of GPRCheck, not {!r}"
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.format(check))
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self.check = check
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self.name = "gpr_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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spec_order = AnyConst(dut.pfv.order.shape())
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spec_index = AnyConst(unsigned(5))
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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 == spec_index)),
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gpr_write.rb.eq(dut.pfv.rb.w_stb & (dut.pfv.rb.index == spec_index)),
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gpr_write.rs.eq(dut.pfv.rs.w_stb & (dut.pfv.rs.index == spec_index)),
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gpr_write.rt.eq(dut.pfv.rt.w_stb & (dut.pfv.rt.index == spec_index)),
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gpr_read .ra.eq(dut.pfv.ra.r_stb & (dut.pfv.ra.index == spec_index)),
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gpr_read .rb.eq(dut.pfv.rb.r_stb & (dut.pfv.rb.index == spec_index)),
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gpr_read .rs.eq(dut.pfv.rs.r_stb & (dut.pfv.rs.index == spec_index)),
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gpr_read .rt.eq(dut.pfv.rt.r_stb & (dut.pfv.rt.index == spec_index)),
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]
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gpr_conflict = Record([("prev", 1), ("curr", 1)])
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gpr_written = Record([("prev", 1)])
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gpr_shadow = Record([("prev", 64)])
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m.submodules.write_enc = write_enc = Encoder(len(gpr_write))
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m.d.comb += write_enc.i.eq(gpr_write)
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with m.If(dut.pfv.stb & write_enc.i.any() & write_enc.n):
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# Write conflict: more then one bit of `gpr_write` is asserted.
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m.d.comb += gpr_conflict.curr.eq(1)
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m.d.sync += gpr_conflict.prev.eq(dut.pfv.order < spec_order)
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with m.If(dut.pfv.stb & (dut.pfv.order < spec_order)):
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with m.If(gpr_write.any()):
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m.d.sync += gpr_written.prev.eq(1)
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with m.If(gpr_write.ra):
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m.d.sync += gpr_shadow.prev.eq(dut.pfv.ra.w_data)
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with m.If(gpr_write.rb):
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m.d.sync += gpr_shadow.prev.eq(dut.pfv.rb.w_data)
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with m.If(gpr_write.rs):
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m.d.sync += gpr_shadow.prev.eq(dut.pfv.rs.w_data)
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with m.If(gpr_write.rt):
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m.d.sync += gpr_shadow.prev.eq(dut.pfv.rt.w_data)
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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 == spec_order),
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Assert(~gpr_conflict.curr),
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Assert(~gpr_conflict.prev),
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]
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with m.If(gpr_written.prev):
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with m.If(gpr_read.ra):
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m.d.comb += Assert(dut.pfv.ra.r_data == gpr_shadow.prev)
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with m.If(gpr_read.rb):
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m.d.comb += Assert(dut.pfv.rb.r_data == gpr_shadow.prev)
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with m.If(gpr_read.rs):
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m.d.comb += Assert(dut.pfv.rs.r_data == gpr_shadow.prev)
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with m.If(gpr_read.rt):
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m.d.comb += Assert(dut.pfv.rt.r_data == gpr_shadow.prev)
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m.d.comb += Assert(~Past(t_post.zero))
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return m
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