Add tests/various/async.{sh,v}

Signed-off-by: Clifford Wolf <clifford@clifford.at>

tests/various/async.sh

@@ -0,0 +1,6 @@
+#!/bin/bash
+set -ex
+../../yosys -q -o async_syn.v -p 'synth; rename uut syn' async.v
+iverilog -o async_sim -DTESTBENCH async.v async_syn.v
+vvp -N async_sim > async.out
+rm -f async_syn.v async_sim async.out async.vcd

tests/various/async.v

@@ -0,0 +1,82 @@
+`define MAXQ 2
+module uut (
+	input clk,
+	input d, r, e,
+	output [`MAXQ:0] q
+);
+	reg q0;
+	always @(posedge clk) begin
+		if (r)
+			q0 <= 0;
+		else if (e)
+			q0 <= d;
+	end
+
+	reg q1;
+	always @(posedge clk, posedge r) begin
+		if (r)
+			q1 <= 0;
+		else if (e)
+			q1 <= d;
+	end
+
+	reg q2;
+	always @(posedge clk, negedge r) begin
+		if (!r)
+			q2 <= 0;
+		else if (!e)
+			q2 <= d;
+	end
+
+	assign q = {q2, q1, q0};
+endmodule
+
+`ifdef TESTBENCH
+module testbench;
+	reg clk;
+	always #5 clk = (clk === 1'b0);
+
+	reg d, r, e;
+
+	wire [`MAXQ:0] q_uut;
+	uut uut (.clk(clk), .d(d), .r(r), .e(e), .q(q_uut));
+
+	wire [`MAXQ:0] q_syn;
+	syn syn (.clk(clk), .d(d), .r(r), .e(e), .q(q_syn));
+
+	task printq;
+		reg [5*8-1:0] msg;
+		begin
+			msg = "OK";
+			if (q_uut != q_syn) msg = "SYN";
+			$display("%6t %b %b %s", $time, q_uut, q_syn, msg);
+			if (msg != "OK") $stop;
+		end
+	endtask
+
+	initial if(0) begin
+		$dumpfile("async.vcd");
+		$dumpvars(0, testbench);
+	end
+
+	initial begin
+		@(posedge clk);
+		d <= 0;
+		r <= 0;
+		e <= 0;
+		@(posedge clk);
+		e <= 1;
+		@(posedge clk);
+		e <= 0;
+		repeat (10000) begin
+			@(posedge clk);
+			printq;
+			d <= $random;
+			r <= $random;
+			e <= $random;
+		end
+		$display("OK");
+		$finish;
+	end
+endmodule
+`endif