First version of zynq cosimulation added

Signed-off-by: Joppe Blondel <joppe@blondel.nl>

examples/zynq7000/SIM/tb_cosim.sv

@@ -0,0 +1,115 @@
+`timescale 1ns / 1ps
+
+module tb_cosim;
+    import "DPI-C" function int start_cosim(string path);
+    import "DPI-C" function void end_cosim();
+    import "DPI-C" function int wait_cosim(output int addr, output int t);
+    import "DPI-C" function void finalize_cosim(int t);
+    import "DPI-C" function void read_cosim(input int value);
+    import "DPI-C" function int write_cosim();
+    
+	// Cosimulation variables
+    integer cosim_ret;
+    reg unsigned [31:0] cosim_address;
+    reg unsigned [31:0] cosim_data;
+	integer timestamp;
+	integer curtime;
+	integer started;
+
+    reg ACLK;
+    reg ARESETN;
+
+    wire [1:0] LED;
+
+    initial begin
+        ACLK = 1'b0;
+        ARESETN = 0'b0;
+    end
+
+    always #5 ACLK = !ACLK;
+
+    initial begin
+        $display("Starting testbench");
+        // Start co-simulation
+        if (start_cosim("unix:/tmp/qemu-rport-_cosim@0")>0) begin
+            $display("ERROR: Could not start co-simulation. Stop simulation");
+            $stop;
+        end
+        $display("Co-simulation started");
+        
+        ARESETN = 1'b0;
+        repeat(2)@(posedge ACLK);
+        ARESETN = 1'b1;
+        repeat(2)@(posedge ACLK);
+
+        // Main loop
+        cosim_ret = 0;
+        while (cosim_ret>=0) begin
+            cosim_ret = wait_cosim(cosim_address, timestamp);
+
+            // Check for end of simulation
+            if (cosim_address=='h7ffffffc) begin
+                break;
+            end
+
+			// Check for start of simulation
+			if (cosim_address=='h7ffffff8) begin
+				curtime = timestamp;
+				cosim_ret = 0;
+				started = 1;
+			end
+
+			// Check for pause of simulation
+			if (cosim_address=='h7ffffff4) begin
+				started = 0;
+				finalize_cosim(curtime);
+			end
+
+			if (started==0) begin
+				continue;
+			end
+
+			while(curtime<timestamp) begin
+				@(posedge ACLK);
+			end
+
+            if (cosim_ret==1) begin
+                // WRITE
+                cosim_data = write_cosim();
+				// ADDR = cosim_address;
+				// WRDAT = cosim_data;
+				// WR = 1'b1;
+				@(posedge ACLK);
+				// WR = 1'b0;
+				// while (WRREADY==1'b0) begin
+				// 	@(posedge ACLK);
+				// end
+            end
+
+            if (cosim_ret==2) begin
+                // READ
+				// ADDR = cosim_address;
+				// RD = 1'b1;
+				@(posedge ACLK);
+				// RD = 1'b0;
+				// while (RDREADY==1'b0) begin
+				// 	@(posedge ACLK);
+				// end
+				@(negedge ACLK);
+				cosim_data = 'hdeadbeef;
+                read_cosim(cosim_data);
+            end
+            finalize_cosim(curtime);
+        end
+
+        $display("Reached end of simulation. Stop Co-simulation");
+        end_cosim();
+        $stop;
+
+    end
+
+    heartbeat #(100000000, 10000000) i_heartbeat(
+        ACLK, ARESETN, LED
+    );
+
+endmodule