Be more aggressive with X-values in the testbench

Signed-off-by: Claire Xenia Wolf <[email protected]>
piso77 · Oct 21, 2020 · 8bb5a6c · 8bb5a6c
1 parent f2a8b32
commit 8bb5a6c
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Showing 2 changed files with 6 additions and 5 deletions.
diff --git a/nerv.sv b/nerv.sv
@@ -18,7 +18,8 @@
  */
 
 module nerv #(
-	parameter [31:0] RESET_ADDR = 32'h 0000_0000
+	parameter [31:0] RESET_ADDR = 32'h 0000_0000,
+	parameter integer NUMREGS = 32
 ) (
 	input clock,
 	input reset,
@@ -85,10 +86,10 @@ module nerv #(
 
 	assign dmem_valid = mem_wr_enable || mem_rd_enable;
 	assign dmem_addr = mem_wr_enable ? mem_wr_addr : mem_rd_enable ? mem_rd_addr : 32'h x;
-	assign dmem_wstrb = mem_wr_enable ? mem_wr_strb : 4'h 0;
+	assign dmem_wstrb = mem_wr_enable ? mem_wr_strb : mem_rd_enable ? 4'h 0 : 4'h x;
 	assign dmem_wdata = mem_wr_enable ? mem_wr_data : 32'h x;
 
-	reg [31:0] regfile [0:31];
+	reg [31:0] regfile [0:NUMREGS-1];
 	wire [31:0] insn;
 	reg [31:0] npc;
 	reg [31:0] pc;

diff --git a/testbench.sv b/testbench.sv
@@ -120,13 +120,13 @@ nerv dut (
 	.stall(stall),
 
 	.imem_addr(imem_addr),
-	.imem_data(imem_data),
+	.imem_data(stall ? 32'bx : imem_data),
 
 	.dmem_valid(dmem_valid),
 	.dmem_addr(dmem_addr),
 	.dmem_wstrb(dmem_wstrb),
 	.dmem_wdata(dmem_wdata),
-	.dmem_rdata(dmem_rdata)
+	.dmem_rdata(stall ? 32'bx : dmem_rdata)
 );
 
 reg [31:0] cycles = 0;