lib: add a DelayLine module
A delay line takes a write and echoes it back N cycles later, with N fixed at compile time. It's a handy primitive to have when wrapping Verilog blackbox modules because the blackbox often specifies something like having 2 cycles of latency, and so you need to bubble the fact that a write occurred 2 cycles ago through to the output so that you can wire up the right implicit conditions.
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package DelayLine;
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import List::*;
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interface DelayLine#(type value);
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method Action _write (value v);
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method value _read();
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method Bool ready();
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endinterface
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module mkDelayLine(Integer delay_cycles, DelayLine#(a) ifc)
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provisos (Bits#(a, a_sz));
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DelayLine#(a) ret = ?;
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if (delay_cycles == 0) begin
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RWire#(a) w <- mkRWire();
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ret = (interface DelayLine;
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method Action _write(a value);
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w.wset(value);
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endmethod
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method a _read() if (w.wget matches tagged Valid .val);
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return val;
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endmethod
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method Bool ready();
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return isValid(w.wget);
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endmethod
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endinterface);
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end
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else begin
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RWire#(a) inputVal <- mkRWire;
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List#(Reg#(Maybe#(a))) delay = tagged Nil;
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for (Integer i = 0; i < delay_cycles; i = i+1) begin
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let r <- mkReg(tagged Invalid);
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delay = cons(r, delay);
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end
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(* no_implicit_conditions, fire_when_enabled *)
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rule pump_line;
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delay[0] <= inputVal.wget();
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for (Integer i = 0; i < delay_cycles-1; i = i+1)
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delay[i+1] <= delay[i];
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endrule
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ret = (interface DelayLine;
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method Action _write(a value);
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inputVal.wset(value);
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endmethod
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method a _read() if (delay[delay_cycles-1] matches tagged Valid .val);
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return val;
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endmethod
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method Bool ready();
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return isValid(delay[delay_cycles-1]);
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endmethod
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endinterface);
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end
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return ret;
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endmodule
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endpackage
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@ -0,0 +1,98 @@
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package DelayLine_Test;
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import Assert::*;
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import StmtFSM::*;
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import Testing::*;
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import Printf::*;
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import List::*;
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import DelayLine::*;
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module mkTB();
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let cycles <- mkTestCycleLimiter(100);
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function Stmt testDelayLine(DelayLine#(Int#(8)) delay, Bit#(32) wantDelay);
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seq
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$display(" RUN delay=%0d", wantDelay);
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action
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delay <= 42;
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cycles.reset_count();
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$display(" write cycle: %0d", cycles.cycles);
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endaction
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repeat (wantDelay-1)
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action
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if (delay.ready) begin
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$display("delay line ready after %0d cycles, want %0d", cycles.count, wantDelay);
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$finish;
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end
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endaction
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// Check the value coming off the delay line and the timing
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// separately, since the delay line read can be blocked by
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// implicit conditions.
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par
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dynamicAssert(delay == 42, "delay output was wrong value");
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action
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dynamicAssert(delay.ready == True, "delay line not ready when expected");
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if (cycles.count != wantDelay) begin
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$display("delay line ready after %0d cycles, want %0d", cycles.count, wantDelay);
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$finish;
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end
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$display(" ready cycle: %0d", cycles.cycles);
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endaction
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endpar
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dynamicAssert(delay.ready == False, "delay line still ready after value yield");
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$display(" OK delay=%0d", wantDelay);
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endseq;
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endfunction
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let delay0 <- mkDelayLine(0);
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let test0 = seq
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$display(" RUN delay=0");
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dynamicAssert(delay0.ready == False, "delay line ready before put");
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par
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action
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delay0 <= 42;
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$display(" write cycle: %0d", cycles.cycles);
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endaction
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action
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dynamicAssert(delay0.ready == True, "delay line not ready on same cycle");
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$display(" read cycle: %0d", cycles.cycles);
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endaction
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dynamicAssert(delay0 == 42, "delay line has wrong value");
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endpar
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dynamicAssert(delay0.ready == False, "delay line ready without write");
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$display(" OK delay=0");
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endseq;
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let delay1 <- mkDelayLine(1);
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let test1 = testDelayLine(delay1, 1);
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let delay2 <- mkDelayLine(2);
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let test2 = testDelayLine(delay2, 2);
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let delay3 <- mkDelayLine(3);
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let test3 = testDelayLine(delay3, 3);
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let delay4 <- mkDelayLine(4);
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let test4 = testDelayLine(delay4, 4);
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mkTest("DelayLine", seq
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test0;
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test1;
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test2;
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test3;
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test4;
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endseq);
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endmodule
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endpackage
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@ -3,13 +3,31 @@ package Testing;
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import Assert::*;
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import StmtFSM::*;
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module mkTestCycleLimit#(Integer max_cycles)();
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Reg#(UInt#(64)) c <- mkReg(fromInteger(max_cycles));
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interface TestCycleLimiter;
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method Bit#(32) cycles();
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rule count;
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dynamicAssert(c > 0, "FAIL: test timed out");
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c <= c-1;
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method Bit#(32) count();
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method Action reset_count();
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endinterface
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module mkTestCycleLimiter#(Integer max_cycles)(TestCycleLimiter);
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Bit#(32) max = fromInteger(max_cycles);
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Reg#(Bit#(32)) cnt <- mkReg(0);
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Reg#(Bit#(32)) lastReset <- mkReg(0);
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(* no_implicit_conditions, fire_when_enabled *)
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rule count_up;
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dynamicAssert(cnt < max, "FAIL: test timed out");
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cnt <= cnt+1;
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endrule
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method cycles = cnt._read;
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method Bit#(32) count();
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return cnt - lastReset;
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endmethod
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method Action reset_count();
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lastReset <= cnt;
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endmethod
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endmodule
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module mkTest#(String name, RStmt#(Bit#(0)) test)();
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22
tasks.py
22
tasks.py
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@ -92,13 +92,18 @@ def build(c, target="."):
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c.run(f"bsc -aggressive-conditions -check-assert -u -verilog -info-dir {out_info} -vdir {out_verilog} -bdir {out_bsc} -p {target.parent}:lib:%/Libraries -show-module-use -show-compiles {target}")
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module_name = Path(f"mk{target.stem}")
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verilog_files.append(out_verilog / module_name.with_suffix(".v"))
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with open(out_verilog / module_name.with_suffix(".use")) as f:
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verilog_files.extend(find_verilog_modules(c, f.read().splitlines()))
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verilog_main_file = out_verilog / module_name.with_suffix(".v")
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if verilog_main_file.is_file():
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verilog_files.append(verilog_main_file)
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use_file = out_verilog / module_name.with_suffix(".use")
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if use_file.is_file():
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with open(out_verilog / module_name.with_suffix(".use")) as f:
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verilog_files.extend(find_verilog_modules(c, f.read().splitlines()))
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print("\nVerilog files for synthesis:")
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for v in verilog_files:
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print(" "+str(v))
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if verilog_files:
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print("\nVerilog files for synthesis:")
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for v in verilog_files:
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print(" "+str(v))
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return verilog_files
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@ -110,6 +115,9 @@ def synth(c, target):
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module_name = Path(f"mk{target.stem}")
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verilog_files = build(c, target)
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if not verilog_files:
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print("\nWARNING: bluespec compile didn't output any verilog files, did you (* synthesize *) something?")
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return
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phase("Logic synthesis")
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yosys_script = out_yosys / "script.ys"
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print(f"Wrote bitstream to {bitstream}")
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@task
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def test(c, target="."):
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def test(c, target):
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for target in expand_test_target(target):
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out_info, out_sim, out_bsc = ensure_build_dirs(target, "info", "sim", "bsc")
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c.run(f"bsc -show-schedule -aggressive-conditions -check-assert -u -sim -info-dir {out_info} -simdir {out_sim} -bdir {out_bsc} -g mkTB -p {target.parent}:lib:%/Libraries {target}")
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