Improved vivado "system" example

2 files changed, 56 insertions, 16 deletions

diff --git a/scripts/vivado/system.v b/scripts/vivado/system.v
index 86449a0..c4882a1 100644
--- a/scripts/vivado/system.v
+++ b/scripts/vivado/system.v
@@ -7,12 +7,15 @@ module system (
 	output reg [7:0] out_byte,
 	output reg       out_byte_en
 );
+	// set this to 0 for better timing but less performance/MHz
+	parameter FAST_MEMORY = 1;
+
 	// 4096 32bit words = 16kB memory
 	parameter MEM_SIZE = 4096;
 
 	wire mem_valid;
 	wire mem_instr;
-	wire mem_ready;
+	reg mem_ready;
 	wire [31:0] mem_addr;
 	wire [31:0] mem_wdata;
 	wire [3:0] mem_wstrb;
@@ -24,7 +27,7 @@ module system (
 	wire [31:0] mem_la_wdata;
 	wire [3:0] mem_la_wstrb;
 
-	picorv32 uut (
+	picorv32 picorv32_core (
 		.clk         (clk         ),
 		.resetn      (resetn      ),
 		.trap        (trap        ),
@@ -45,21 +48,54 @@ module system (
 	reg [31:0] memory [0:MEM_SIZE-1];
 	initial $readmemh("firmware.hex", memory);
 
-	assign mem_ready = 1;
+	reg [31:0] m_read_data;
+	reg m_read_en;
 
-	always @(posedge clk) begin
-		out_byte_en <= 0;
-		mem_rdata <= memory[mem_la_addr >> 2];
-		if (mem_la_write && (mem_la_addr >> 2) < MEM_SIZE) begin
-			if (mem_la_wstrb[0]) memory[mem_la_addr >> 2][ 7: 0] <= mem_la_wdata[ 7: 0];
-			if (mem_la_wstrb[1]) memory[mem_la_addr >> 2][15: 8] <= mem_la_wdata[15: 8];
-			if (mem_la_wstrb[2]) memory[mem_la_addr >> 2][23:16] <= mem_la_wdata[23:16];
-			if (mem_la_wstrb[3]) memory[mem_la_addr >> 2][31:24] <= mem_la_wdata[31:24];
+	generate if (FAST_MEMORY) begin
+		always @(posedge clk) begin
+			mem_ready <= 1;
+			out_byte_en <= 0;
+			mem_rdata <= memory[mem_la_addr >> 2];
+			if (mem_la_write && (mem_la_addr >> 2) < MEM_SIZE) begin
+				if (mem_la_wstrb[0]) memory[mem_la_addr >> 2][ 7: 0] <= mem_la_wdata[ 7: 0];
+				if (mem_la_wstrb[1]) memory[mem_la_addr >> 2][15: 8] <= mem_la_wdata[15: 8];
+				if (mem_la_wstrb[2]) memory[mem_la_addr >> 2][23:16] <= mem_la_wdata[23:16];
+				if (mem_la_wstrb[3]) memory[mem_la_addr >> 2][31:24] <= mem_la_wdata[31:24];
+			end
+			else
+			if (mem_la_write && mem_la_addr == 32'h1000_0000) begin
+				out_byte_en <= 1;
+				out_byte <= mem_la_wdata;
+			end
 		end
-		else
-		if (mem_la_write && mem_la_addr == 32'h1000_0000) begin
-			out_byte_en <= 1;
-			out_byte <= mem_la_wdata;
+	end else begin
+		always @(posedge clk) begin
+			m_read_en <= 0;
+			mem_ready <= mem_valid && !mem_ready && m_read_en;
+
+			m_read_data <= memory[mem_addr >> 2];
+			mem_rdata <= m_read_data;
+
+			out_byte_en <= 0;
+
+			(* parallel_case *)
+			case (1)
+				mem_valid && !mem_ready && !mem_wstrb && (mem_addr >> 2) < MEM_SIZE: begin
+					m_read_en <= 1;
+				end
+				mem_valid && !mem_ready && |mem_wstrb && (mem_addr >> 2) < MEM_SIZE: begin
+					if (mem_wstrb[0]) memory[mem_addr >> 2][ 7: 0] <= mem_wdata[ 7: 0];
+					if (mem_wstrb[1]) memory[mem_addr >> 2][15: 8] <= mem_wdata[15: 8];
+					if (mem_wstrb[2]) memory[mem_addr >> 2][23:16] <= mem_wdata[23:16];
+					if (mem_wstrb[3]) memory[mem_addr >> 2][31:24] <= mem_wdata[31:24];
+					mem_ready <= 1;
+				end
+				mem_valid && !mem_ready && |mem_wstrb && mem_addr == 32'h1000_0000: begin
+					out_byte_en <= 1;
+					out_byte <= mem_wdata;
+					mem_ready <= 1;
+				end
+			endcase
 		end
-	end
+	end endgenerate
 endmodule
diff --git a/scripts/vivado/system_tb.v b/scripts/vivado/system_tb.v
index f0676ca..a66d612 100644
--- a/scripts/vivado/system_tb.v
+++ b/scripts/vivado/system_tb.v
@@ -6,6 +6,10 @@ module system_tb;
 
 	reg resetn = 0;
 	initial begin
+		if ($test$plusargs("vcd")) begin
+			$dumpfile("system.vcd");
+			$dumpvars(0, system_tb);
+		end
 		repeat (100) @(posedge clk);
 		resetn <= 1;
 	end