src/scoreboard/dependence_cell.py

   1 from nmigen.compat.sim import run_simulation
   2 from nmigen.cli import verilog, rtlil
   3 from nmigen import Module, Signal, Elaboratable, Array, Cat
   4 from nmutil.latch import SRLatch
   5
   6
   7 class DependenceCell(Elaboratable):
   8     """ implements 11.4.7 mitch alsup dependence cell, p27
   9     """
  10     def __init__(self):
  11         # inputs
  12         self.dest_i = Signal(reset_less=True)     # Dest in (top)
  13         self.src1_i = Signal(reset_less=True)     # oper1 in (top)
  14         self.src2_i = Signal(reset_less=True)     # oper2 in (top)
  15         self.issue_i = Signal(reset_less=True)    # Issue in (top)
  16
  17         self.go_wr_i = Signal(reset_less=True) # Go Write in (left)
  18         self.go_rd_i = Signal(reset_less=True)  # Go Read in (left)
  19
  20         # for Register File Select Lines (vertical)
  21         self.dest_rsel_o = Signal(reset_less=True)  # dest reg sel (bottom)
  22         self.src1_rsel_o = Signal(reset_less=True)  # src1 reg sel (bottom)
  23         self.src2_rsel_o = Signal(reset_less=True)  # src2 reg sel (bottom)
  24
  25         # for Function Unit "forward progress" (horizontal)
  26         self.dest_fwd_o = Signal(reset_less=True)   # dest FU fw (right)
  27         self.src1_fwd_o = Signal(reset_less=True)   # src1 FU fw (right)
  28         self.src2_fwd_o = Signal(reset_less=True)   # src2 FU fw (right)
  29
  30     def elaborate(self, platform):
  31         m = Module()
  32         m.submodules.dest_l = dest_l = SRLatch() # clock-sync'd
  33         m.submodules.src1_l = src1_l = SRLatch() # clock-sync'd
  34         m.submodules.src2_l = src2_l = SRLatch() # clock-sync'd
  35
  36         # destination latch: reset on go_wr HI, set on dest and issue
  37         m.d.comb += dest_l.s.eq(self.issue_i & self.dest_i)
  38         m.d.comb += dest_l.r.eq(self.go_wr_i)
  39
  40         # src1 latch: reset on go_rd HI, set on src1_i and issue
  41         m.d.comb += src1_l.s.eq(self.issue_i & self.src1_i)
  42         m.d.comb += src1_l.r.eq(self.go_rd_i)
  43
  44         # src2 latch: reset on go_rd HI, set on op2_i and issue
  45         m.d.comb += src2_l.s.eq(self.issue_i & self.src2_i)
  46         m.d.comb += src2_l.r.eq(self.go_rd_i)
  47
  48         # FU "Forward Progress" (read out horizontally)
  49         m.d.comb += self.dest_fwd_o.eq(dest_l.q & self.go_wr_i)
  50         m.d.comb += self.src1_fwd_o.eq(src1_l.q & self.go_rd_i)
  51         m.d.comb += self.src2_fwd_o.eq(src2_l.q & self.go_rd_i)
  52
  53         # Register File Select (read out vertically)
  54         m.d.comb += self.dest_rsel_o.eq(dest_l.q & self.dest_i)
  55         m.d.comb += self.src1_rsel_o.eq(src1_l.q & self.src1_i)
  56         m.d.comb += self.src2_rsel_o.eq(src2_l.q & self.src2_i)
  57
  58         return m
  59
  60     def __iter__(self):
  61         yield self.dest_i
  62         yield self.src1_i
  63         yield self.src2_i
  64         yield self.issue_i
  65         yield self.go_wr_i
  66         yield self.go_rd_i
  67         yield self.dest_rsel_o
  68         yield self.src1_rsel_o
  69         yield self.src2_rsel_o
  70         yield self.dest_fwd_o
  71         yield self.src1_fwd_o
  72         yield self.src2_fwd_o
  73
  74     def ports(self):
  75         return list(self)
  76
  77
  78 class DependencyRow(Elaboratable):
  79     def __init__(self, n_reg_col):
  80         self.n_reg_col = n_reg_col
  81
  82         # ----
  83         # fields all match DependencyCell precisely
  84
  85         self.dest_i = Signal(n_reg_col, reset_less=True)
  86         self.src1_i = Signal(n_reg_col, reset_less=True)
  87         self.src2_i = Signal(n_reg_col, reset_less=True)
  88         self.issue_i = Signal(n_reg_col, reset_less=True)
  89
  90         self.go_wr_i = Signal(n_reg_col, reset_less=True)
  91         self.go_rd_i = Signal(n_reg_col, reset_less=True)
  92
  93         self.dest_rsel_o = Signal(n_reg_col, reset_less=True)
  94         self.src1_rsel_o = Signal(n_reg_col, reset_less=True)
  95         self.src2_rsel_o = Signal(n_reg_col, reset_less=True)
  96
  97         self.dest_fwd_o = Signal(n_reg_col, reset_less=True)
  98         self.src1_fwd_o = Signal(n_reg_col, reset_less=True)
  99         self.src2_fwd_o = Signal(n_reg_col, reset_less=True)
 100
 101     def elaborate(self, platform):
 102         m = Module()
 103         rcell = Array(DependenceCell() for f in range(self.n_reg_col))
 104         for rn in range(self.n_reg_col):
 105             setattr(m.submodules, "dm_r%d" % rn, rcell[rn])
 106
 107         # ---
 108         # connect Dep dest/src to module dest/src
 109         # ---
 110         dest_i = []
 111         src1_i = []
 112         src2_i = []
 113         for rn in range(self.n_reg_col):
 114             dc = rcell[rn]
 115             # accumulate cell inputs dest/src1/src2
 116             dest_i.append(dc.dest_i)
 117             src1_i.append(dc.src1_i)
 118             src2_i.append(dc.src2_i)
 119         # wire up inputs from module to row cell inputs (Cat is gooood)
 120         m.d.comb += [Cat(*dest_i).eq(self.dest_i),
 121                      Cat(*src1_i).eq(self.src1_i),
 122                      Cat(*src2_i).eq(self.src2_i),
 123                     ]
 124
 125         # ---
 126         # connect Dep issue_i/go_rd_i/go_wr_i to module issue_i/go_rd/go_wr
 127         # ---
 128         go_rd_i = []
 129         go_wr_i = []
 130         issue_i = []
 131         for rn in range(self.n_reg_col):
 132             dc = rcell[rn]
 133             # accumulate cell outputs for issue/go_rd/go_wr
 134             go_rd_i.append(dc.go_rd_i)
 135             go_wr_i.append(dc.go_wr_i)
 136             issue_i.append(dc.issue_i)
 137         # wire up inputs from module to row cell inputs (Cat is gooood)
 138         m.d.comb += [Cat(*go_rd_i).eq(self.go_rd_i),
 139                      Cat(*go_wr_i).eq(self.go_wr_i),
 140                      Cat(*issue_i).eq(self.issue_i),
 141                     ]
 142
 143         return m
 144
 145
 146 def dcell_sim(dut):
 147     yield dut.dest_i.eq(1)
 148     yield dut.issue_i.eq(1)
 149     yield
 150     yield dut.issue_i.eq(0)
 151     yield
 152     yield dut.src1_i.eq(1)
 153     yield dut.issue_i.eq(1)
 154     yield
 155     yield
 156     yield
 157     yield dut.issue_i.eq(0)
 158     yield
 159     yield dut.go_rd_i.eq(1)
 160     yield
 161     yield dut.go_rd_i.eq(0)
 162     yield
 163     yield dut.go_wr_i.eq(1)
 164     yield
 165     yield dut.go_wr_i.eq(0)
 166     yield
 167
 168 def test_dcell():
 169     dut = DependenceCell()
 170     vl = rtlil.convert(dut, ports=dut.ports())
 171     with open("test_dcell.il", "w") as f:
 172         f.write(vl)
 173
 174     run_simulation(dut, dcell_sim(dut), vcd_name='test_dcell.vcd')
 175
 176 if __name__ == '__main__':
 177     test_dcell()