1 from nmigen
.compat
.sim
import run_simulation
2 from nmigen
.cli
import verilog
, rtlil
3 from nmigen
import Module
, Signal
, Elaboratable
5 from nmutil
.latch
import SRLatch
, latchregister
8 class ComputationUnitNoDelay(Elaboratable
):
9 def __init__(self
, rwid
, opwid
, alu
):
13 self
.counter
= Signal(3)
14 self
.go_rd_i
= Signal(reset_less
=True) # go read in
15 self
.go_wr_i
= Signal(reset_less
=True) # go write in
16 self
.issue_i
= Signal(reset_less
=True) # fn issue in
18 self
.oper_i
= Signal(opwid
, reset_less
=True) # opcode in
19 self
.src1_i
= Signal(rwid
, reset_less
=True) # oper1 in
20 self
.src2_i
= Signal(rwid
, reset_less
=True) # oper2 in
22 self
.busy_o
= Signal(reset_less
=True) # fn busy out
23 self
.data_o
= Signal(rwid
, reset_less
=True) # Dest out
24 self
.req_rel_o
= Signal(reset_less
=True) # release request out (valid_o)
26 def elaborate(self
, platform
):
28 m
.submodules
.alu
= self
.alu
29 m
.submodules
.src_l
= src_l
= SRLatch(sync
=False)
30 m
.submodules
.opc_l
= opc_l
= SRLatch(sync
=False)
31 m
.submodules
.req_l
= req_l
= SRLatch(sync
=False)
33 # This is fascinating and very important to observe that this
34 # is in effect a "3-way revolving door". At no time may all 3
35 # latches be set at the same time.
37 # opcode latch (not using go_rd_i) - inverted so that busy resets to 0
38 m
.d
.comb
+= opc_l
.s
.eq(self
.issue_i
) # XXX NOTE: INVERTED FROM book!
39 m
.d
.comb
+= opc_l
.r
.eq(self
.go_wr_i
) # XXX NOTE: INVERTED FROM book!
41 # src operand latch (not using go_wr_i)
42 m
.d
.comb
+= src_l
.s
.eq(self
.issue_i
)
43 m
.d
.comb
+= src_l
.r
.eq(self
.go_rd_i
)
45 # dest operand latch (not using issue_i)
46 m
.d
.comb
+= req_l
.s
.eq(self
.go_rd_i
)
47 m
.d
.comb
+= req_l
.r
.eq(self
.go_wr_i
)
50 # XXX NOTE: sync on req_rel_o and data_o due to simulation lock-up
54 m
.d
.comb
+= self
.busy_o
.eq(opc_l
.q
) # busy out
56 with m
.If(req_l
.qn
& opc_l
.q
& (self
.counter
== 0)):
57 m
.d
.sync
+= self
.counter
.eq(3)
58 with m
.If(self
.counter
> 0):
59 m
.d
.sync
+= self
.counter
.eq(self
.counter
- 1)
60 with m
.If((self
.counter
== 1) |
(self
.counter
== 0)):
61 m
.d
.comb
+= self
.req_rel_o
.eq(req_l
.q
& opc_l
.q
) # req release out
63 # create a latch/register for src1/src2
64 latchregister(m
, self
.src1_i
, self
.alu
.a
, src_l
.q
)
65 latchregister(m
, self
.src2_i
, self
.alu
.b
, src_l
.q
)
67 # m.d.comb += self.alu.op.eq(self.oper_i)
69 # create a latch/register for the operand
70 latchregister(m
, self
.oper_i
, self
.alu
.op
, src_l
.q
)
72 # and one for the output from the ALU
73 data_o
= Signal(self
.rwid
, reset_less
=True) # Dest register
74 latchregister(m
, self
.alu
.o
, data_o
, req_l
.q
)
76 with m
.If(self
.go_wr_i
):
77 m
.d
.comb
+= self
.data_o
.eq(data_o
)
81 def scoreboard_sim(dut
):
82 yield dut
.dest_i
.eq(1)
83 yield dut
.issue_i
.eq(1)
85 yield dut
.issue_i
.eq(0)
87 yield dut
.src1_i
.eq(1)
88 yield dut
.issue_i
.eq(1)
92 yield dut
.issue_i
.eq(0)
94 yield dut
.go_read_i
.eq(1)
96 yield dut
.go_read_i
.eq(0)
98 yield dut
.go_write_i
.eq(1)
100 yield dut
.go_write_i
.eq(0)
103 def test_scoreboard():
104 dut
= Scoreboard(32, 8)
105 vl
= rtlil
.convert(dut
, ports
=dut
.ports())
106 with
open("test_scoreboard.il", "w") as f
:
109 run_simulation(dut
, scoreboard_sim(dut
), vcd_name
='test_scoreboard.vcd')
111 if __name__
== '__main__':