Move ALU test cases to external testcase file

This makes is a little easier to create new ALU testcases and to quickly
read and understand the existing testcases.  Additionally, the test bench
itself can now report when a test fails, rather than requiring inspection
on the waveform (though the waveform is still available).

1 files changed, 28 insertions, 46 deletions

diff --git a/alu_tb.v b/alu_tb.v
index 6afafbc..8342e6c 100644
--- a/alu_tb.v
+++ b/alu_tb.v
@@ -1,3 +1,4 @@
+`include "testbench.vh"
 `timescale 1 ns / 100 ps
 
 module alu_tb ();
@@ -11,58 +12,39 @@ module alu_tb ();
 	wire carry;
 	reg expected_carry;
 
+	reg [3*8:0] opstr;
+	integer file, r;
+
 	initial begin
 		$dumpfile("alu_tb.vcd");
 		$dumpvars(0, alu_tb);
 
-		x = 16'h0123;
-		y = 16'h1234;
-
-		op = 4'h0;  // add
-		expected_result = 16'h1357;
-		expected_zero = 1'b0;
-		expected_carry = 1'b0;
-
-		#2
-		op = 4'h1;  // subtract
-		expected_result = 16'hEEEF;
-		expected_carry = 1'b1;
-		expected_zero = 1'b0;
-
-		#2
-		y = 16'h0123;
-		expected_result = 16'h0;
-		expected_zero = 1'b1;
-		expected_carry = 1'b0;
-
-		#2
-		y = 16'h1234;
-		op = 4'h2;  // multiply
-		expected_result = 16'hB11C;
-		expected_zero = 1'b0;
-		expected_carry = 1'b0;
+		file = $fopenr("tests/alu");
+
+		skip_comments(file);
+		while (!$feof(file)) begin
+			r = $fscanf(file, " 0x%x %3s 0x%x = 0x%x Z=%x C=%x\n", x, opstr, y, expected_result, expected_zero, expected_carry);
+
+			case (opstr)
+				"+" : op = 0;
+				"-" : op = 1;
+				"*" : op = 2;
+				"/" : op = 3;
+				"&" : op = 4;
+				"|" : op = 5;
+				"^" : op = 6;
+				default : op = 0;
+			endcase
+
+			#2
+			if (result != expected_result || zero != expected_zero || carry != expected_carry) begin
+				$display("TEST FAILED: 0x%04x %3s 0x%04x = 0x%04x Z=%x C=%x (expected 0x%04x Z=%x C=%x)", x, opstr, y, result, zero, carry, expected_result, expected_zero, expected_carry);
+			end
+			skip_comments(file);
+		end
 
 		#2
-		x = 16'h3E58;
-		y = 16'h0078;
-		op = 4'h3;  // divide
-		expected_result = 16'h0085;
-
-		#2
-		x = 16'hAF74;
-		y = 16'h7CC7;
-		op = 4'h4;  // and
-		expected_result = 16'h2C44;
-
-		#2
-		op = 4'h5;  // or
-		expected_result = 16'hFFF7;
-
-		#2
-		op = 4'h6;  // xor
-		expected_result = 16'hD3B3;
-
-		#5
+		$fclose(file);
 		$finish;
 	end