1 files changed, 171 insertions, 0 deletions

diff --git a/rtl/tb_lisp_coproc.sv b/rtl/tb_lisp_coproc.sv
new file mode 100644
index 0000000..6c39aa4
--- /dev/null
+++ b/rtl/tb_lisp_coproc.sv
@@ -0,0 +1,171 @@
+`timescale 1ns/1ps
+
+module tb_lisp_coproc;
+
+    // Testbench signals
+    reg        clk;
+    reg        rst;
+    reg        cs;
+    reg        rw;      // 0=Write, 1=Read
+    reg [2:0]  addr;
+    reg [7:0]  data_in;
+    wire [7:0] data_out;
+    
+    // Test variables
+    reg [7:0]  read_data;
+    integer i; 
+    
+    // Instantiate the DUT
+    lisp_coproc dut (
+        .clk(clk),
+        .rst(rst),
+        .cs(cs),
+        .rw(rw),
+        .addr(addr),
+        .data_in(data_in),
+        .data_out(data_out)
+    );
+    
+    // Clock generation
+    initial begin
+        clk = 0;
+        forever #5 clk = ~clk;
+    end
+    
+    // CPU Write Task
+    task cpu_write;
+        input [2:0] addr_in;
+        input [7:0] data_in_in;
+        begin
+            @(posedge clk);
+            cs = 1'b1;
+            rw = 1'b0;  // Write
+            addr = addr_in;
+            data_in = data_in_in;
+            @(posedge clk);
+            cs = 1'b0;
+        end
+    endtask
+    
+    // CPU Read Task
+    task cpu_read;
+        input [2:0] addr_in;
+        output [7:0] data_out_out;
+        reg [7:0] status;
+        begin
+            // Poll until not busy
+            do begin
+                @(posedge clk);
+                cs = 1'b1;
+                rw = 1'b1;  // Read
+                addr = 3'h4;  // Status register
+                @(posedge clk);
+                status = data_out;
+                cs = 1'b0;
+            end while (status[0]);  // Check BUSY bit
+            
+            // Read the requested address
+            @(posedge clk);
+            cs = 1'b1;
+            rw = 1'b1;  // Read
+            addr = addr_in;
+            @(posedge clk);
+            data_out_out = data_out;
+            cs = 1'b0;
+        end
+    endtask
+    
+    // Test Sequence
+    initial begin
+        // Initialize signals
+        rst = 1'b1;
+        cs = 1'b0;
+        rw = 1'b0;
+        addr = 3'h0;
+        data_in = 8'h00;
+        
+        // Apply reset
+        #20;
+        rst = 1'b0;
+        #20;
+        
+        // Test 1: Reset Test
+        $display("Test 1: Reset Test");
+        cpu_read(3'h4, read_data);  // Read STATUS
+        $display("STATUS after reset: 0x%02h (expected: 0x00)", read_data);
+        if (read_data != 8'h00) $display("ERROR: Reset test failed");
+        
+        // Test 2: ADD Test
+        $display("\nTest 2: ADD Test");
+        cpu_write(3'h1, 8'h85);  // ARG1 = NUMBER(5)
+        cpu_write(3'h2, 8'h86);  // ARG2 = NUMBER(6)
+        cpu_write(3'h0, 8'h06);  // OPCODE = ADD
+        
+        cpu_read(3'h3, read_data);  // Read RESULT
+        $display("ADD Result: 0x%02h (expected: 0x8B, NUMBER(11))", read_data);
+        if (read_data != 8'h8B) $display("ERROR: ADD test failed");
+        
+        cpu_read(3'h4, read_data);  // Read STATUS
+        $display("STATUS after ADD: 0x%02h (expected: 0x00, ZERO=0)", read_data);
+        if (read_data != 8'h00) $display("ERROR: ADD status test failed");
+        
+        // Test 3: CONS Test
+        $display("\nTest 3: CONS Test");
+        cpu_write(3'h1, 8'h41);  // ARG1 = ATOM('T')
+        cpu_write(3'h2, 8'h42);  // ARG2 = ATOM('B')
+        cpu_write(3'h0, 8'h01);  // OPCODE = CONS
+        
+        cpu_read(3'h3, read_data);  // Read RESULT
+        $display("CONS Result: 0x%02h (expected: 0xC0, CONS(0))", read_data);
+        if (read_data != 8'hC0) $display("ERROR: CONS test failed");
+        
+        // Test CAR and CDR
+        cpu_write(3'h1, read_data);  // Use the CONS result as ARG1
+        cpu_write(3'h0, 8'h02);      // OPCODE = CAR
+        
+        cpu_read(3'h3, read_data);   // Read RESULT
+        $display("CAR Result: 0x%02h (expected: 0x41, ATOM('T'))", read_data);
+        if (read_data != 8'h41) $display("ERROR: CAR test failed");
+        
+        cpu_write(3'h1, 8'hC0);      // ARG1 = CONS(0)
+        cpu_write(3'h0, 8'h03);      // OPCODE = CDR
+        
+        cpu_read(3'h3, read_data);   // Read RESULT
+        $display("CDR Result: 0x%02h (expected: 0x42, ATOM('B'))", read_data);
+        if (read_data != 8'h42) $display("ERROR: CDR test failed");
+        
+        // Test 4: Error Test (CAR on a Number)
+        $display("\nTest 4: Error Test (CAR on a Number)");
+        cpu_write(3'h1, 8'h85);  // ARG1 = NUMBER(5)
+        cpu_write(3'h0, 8'h02);  // OPCODE = CAR
+        
+        cpu_read(3'h4, read_data);  // Read STATUS
+        $display("STATUS after CAR on Number: 0x%02h (expected: 0x04, ERR_TYPE=1)", read_data);
+        if (read_data != 8'h04) $display("ERROR: Error test failed");
+        
+        // Test 5: Heap Full Test
+        $display("\nTest 5: Heap Full Test");
+        // Fill the heap with CONS operations
+        // Since bump_alloc is now 2, we have used 2 cells. 
+        // 16 cells total. 14 left. 7 more CONS possible.
+        for (i = 0; i < 7; i = i + 1) begin 
+            cpu_write(3'h1, 8'h41);  
+            cpu_write(3'h2, 8'h42);  
+            cpu_write(3'h0, 8'h01);  
+            cpu_read(3'h3, read_data); 
+        end
+        
+        // One more CONS should cause heap full error
+        cpu_write(3'h1, 8'h41); 
+        cpu_write(3'h2, 8'h42); 
+        cpu_write(3'h0, 8'h01); 
+        
+        cpu_read(3'h4, read_data);  // Read STATUS
+        $display("STATUS after Heap Full: 0x%02h (expected: 0x02, ERR_HEAP_FULL=1)", read_data);
+        if (read_data != 8'h02) $display("ERROR: Heap Full test failed");
+        
+        $display("\nAll tests completed.");
+        $finish;
+    end
+
+endmodule