iverilog: Towards iverilog support

Author: thommythomaso

iverilog/test.v

@@ -0,0 +1,86 @@
+// Copyright 2025 ETH Zurich and University of Bologna.
+// Solderpad Hardware License, Version 0.51, see LICENSE for details.
+// SPDX-License-Identifier: SHL-0.51
+//
+// Authors:
+// - Thomas Benz <tbenz@iis.ee.ethz.ch>
+
+`timescale 1ns/1ns
+module fbtb_croc_soc();
+
+    localparam time Period     = 100ns;
+    localparam time PeriodHalf = Period / 2;
+    localparam time TAppl      = 20ns;
+    localparam time TTest      = 80ns;
+
+    int    fd         = 0;
+    int    sim_time   = 0;
+    int    ret        = 0;
+    string line;
+    logic  clk_sample = 0;
+
+    // chip signals from file
+    logic        clk_i;
+    logic        rst_ni;
+    logic        ref_clk_i;
+    logic        testmode_i;
+    logic        fetch_en_i;
+    logic        status_o, status_to;
+    logic        jtag_tck_i;
+    logic        jtag_tdi_i;
+    logic        jtag_tdo_o, jtag_tdo_to;
+    logic        jtag_tms_i;
+    logic        jtag_trst_ni;
+    logic        uart_rx_i;
+    logic        uart_tx_o, uart_tx_to;
+    logic [15:0] gpio_i;
+    logic [15:0] gpio_o, gpio_to;
+    logic [15:0] gpio_out_en_o, gpio_out_en_to;
+
+    initial begin
+        forever begin
+            clk_sample = !clk_sample;
+            #PeriodHalf;
+        end
+    end
+
+    initial begin
+        fd = $fopen("../vsim/stimuli.txt", "r");
+        while (!$feof(fd)) begin
+            // fetch line
+            ret = $fgets(line, fd);
+            // parse line, apply data to chip
+            #TAppl;
+            ret = $fscanf(fd, "%010d.%01b%01b%01b%01b%01b%01b%01b%01b%01b%01b%16b.%01b%01b%01b%16b%16b",
+                sim_time,
+                clk_i,
+                rst_ni,
+                ref_clk_i,
+                testmode_i,
+                fetch_en_i,
+                jtag_tck_i,
+                jtag_tdi_i,
+                jtag_tms_i,
+                jtag_trst_ni,
+                uart_rx_i,
+                gpio_i,
+                status_to,
+                jtag_tdo_to,
+                uart_tx_to,
+                gpio_to,
+                gpio_out_en_to
+            );
+            // test outputs
+            #(TTest - TAppl);
+            if (status_o      !== status_to     )$warning("Output mismatch status_o      (%01b instead of %01b) at: %010d", status_o,      status_to,      sim_time);
+            if (jtag_tdo_o    !== jtag_tdo_to   )$warning("Output mismatch jtag_tdo_o    (%01b instead of %01b) at: %010d", jtag_tdo_o,    jtag_tdo_to,    sim_time);
+            if (uart_tx_o     !== uart_tx_to    )$warning("Output mismatch uart_tx_o     (%01b instead of %01b) at: %010d", uart_tx_o,     uart_tx_to,     sim_time);
+            if (gpio_o        !== gpio_to       )$warning("Output mismatch gpio_o        (%01b instead of %01b) at: %010d", gpio_o,        gpio_to,        sim_time);
+            if (gpio_out_en_o !== gpio_out_en_to)$warning("Output mismatch gpio_out_en_o (%01b instead of %01b) at: %010d", gpio_out_en_o, gpio_out_en_to, sim_time);
+            // next sample
+            @(posedge clk_sample);
+        end
+        $finish;
+        $fclose(fd);
+    end
+endmodule

rtl/tb_croc_soc.sv

@@ -399,6 +399,47 @@ module tb_croc_soc #(
     assign gpio_i[ 3:0] = '0;
     assign gpio_i[ 7:4] = gpio_out_en_o[3:0] & gpio_o[3:0];
 
+    int fd = 0;
+    initial begin
+        int i  = 0;
+        fd = $fopen ("stimuli.txt", "w");
+        forever begin
+            // wait one delta cycle
+            #0;
+            // write time
+            $fwrite(fd, "%010d", $time);
+            $fwrite(fd, ".");
+            // write stimuli
+            #TAppl;
+            $fwrite(fd, "%01b%01b%01b%01b%01b%01b%01b%01b%01b%01b%16b",
+                    i_croc_soc.clk_i,
+                    i_croc_soc.rst_ni,
+                    i_croc_soc.ref_clk_i,
+                    i_croc_soc.testmode_i,
+                    i_croc_soc.fetch_en_i,
+                    i_croc_soc.jtag_tck_i,
+                    i_croc_soc.jtag_tdi_i,
+                    i_croc_soc.jtag_tms_i,
+                    i_croc_soc.jtag_trst_ni,
+                    i_croc_soc.uart_rx_i,
+                    i_croc_soc.gpio_i
+            );
+            $fwrite(fd, ".");
+            // write responses
+            #(TTest-TAppl);
+            $fwrite(fd, "%01b%01b%01b%16b%16b",
+                    i_croc_soc.status_o,
+                    i_croc_soc.jtag_tdo_o,
+                    i_croc_soc.uart_tx_o,
+                    i_croc_soc.gpio_o,
+                    i_croc_soc.gpio_out_en_o
+            );
+            // wait for next clock
+            $fwrite(fd, "\n");
+            @(posedge clk);
+        end
+    end
+
 
     /////////////////
     //  Testbench  //

vsim/.gitignore

@@ -5,3 +5,4 @@ transcript
 vsim.wlf
 modelsim.ini
 *.vcd
+stimuli.txt