src/scoreboard/shadow_fn.py

   1 from nmigen.compat.sim import run_simulation
   2 from nmigen.cli import verilog, rtlil
   3 from nmigen import Module, Signal, Cat, Elaboratable
   4 from nmutil.latch import SRLatch
   5
   6
   7 class ShadowFn(Elaboratable):
   8     """ implements shadowing 11.5.1, p55, just the individual shadow function
   9     """
  10     def __init__(self):
  11
  12         # inputs
  13         self.issue_i = Signal(reset_less=True)
  14         self.shadow_i  = Signal(reset_less=True)
  15         self.s_fail_i  = Signal(reset_less=True)
  16         self.s_good_i  = Signal(reset_less=True)
  17
  18         # outputs
  19         self.shadow_o = Signal(reset_less=True)
  20         self.recover_o = Signal(reset_less=True)
  21
  22     def elaborate(self, platform):
  23         m = Module()
  24         m.submodules.sl = sl = SRLatch(sync=False)
  25
  26         cq = Signal() # resets to 0
  27         m.d.sync += cq.eq(sl.q)
  28
  29         m.d.comb += sl.s.eq(self.shadow_i & self.issue_i & ~self.s_good_i)
  30         m.d.comb += sl.r.eq(self.s_good_i | (self.issue_i & ~self.shadow_i))
  31         m.d.comb += self.recover_o.eq((cq | sl.q) & self.s_fail_i)
  32         m.d.comb += self.shadow_o.eq((cq | sl.q))
  33
  34         return m
  35
  36     def __iter__(self):
  37         yield self.issue_i
  38         yield self.shadow_i
  39         yield self.s_fail_i
  40         yield self.s_good_i
  41         yield self.shadow_o
  42         yield self.recover_o
  43
  44     def ports(self):
  45         return list(self)
  46
  47
  48 def shadow_fn_unit_sim(dut):
  49     yield dut.dest_i.eq(1)
  50     yield dut.issue_i.eq(1)
  51     yield
  52     yield dut.issue_i.eq(0)
  53     yield
  54     yield dut.src1_i.eq(1)
  55     yield dut.issue_i.eq(1)
  56     yield
  57     yield
  58     yield
  59     yield dut.issue_i.eq(0)
  60     yield
  61     yield dut.go_rd_i.eq(1)
  62     yield
  63     yield dut.go_rd_i.eq(0)
  64     yield
  65     yield dut.go_wr_i.eq(1)
  66     yield
  67     yield dut.go_wr_i.eq(0)
  68     yield
  69
  70
  71 def test_shadow_fn_unit():
  72     dut = ShadowFn()
  73     vl = rtlil.convert(dut, ports=dut.ports())
  74     with open("test_shadow_fn_unit.il", "w") as f:
  75         f.write(vl)
  76
  77     run_simulation(dut, shadow_fn_unit_sim(dut),
  78                    vcd_name='test_shadow_fn_unit.vcd')
  79
  80 if __name__ == '__main__':
  81     test_shadow_fn_unit()