// tb_rng.cpp - Verilator C++ testbench for rng_sync
//
// Drives valid_i pulses and prints 256-bit LFSR output values.
// Reads a hex input file to determine how many vectors to generate
// (one line per vector, content ignored).
// Prints "RESULT: <64-char hex>" for each output.
//
// Clock: 10ns period. Reset: 2 cycles low.
// Timeout: 100,000 cycles.

#include <iostream>
#include <fstream>
#include <string>
#include <cstdio>
#include "Vrng_sync.h"
#include "verilated.h"

#define CLK_PERIOD_NS 10.0

static vluint64_t main_time = 0;

double sc_time_stamp() {
    return main_time;
}

int main(int argc, char** argv) {
    Verilated::commandArgs(argc, argv);

    // Parse +VECTOR_FILE= plusarg
    const char* vector_file = NULL;
    for (int i = 1; i < argc; i++) {
        std::string arg(argv[i]);
        if (arg.rfind("+VECTOR_FILE=", 0) == 0) {
            vector_file = argv[i] + 13;
        }
    }

    if (!vector_file) {
        std::cerr << "ERROR: +VECTOR_FILE= not specified" << std::endl;
        return 1;
    }

    std::ifstream infile(vector_file);
    if (!infile.is_open()) {
        std::cerr << "ERROR: Cannot open vector file: " << vector_file << std::endl;
        return 1;
    }

    // Count non-empty, non-comment lines to determine vector count
    int num_vectors = 0;
    std::string line;
    while (std::getline(infile, line)) {
        if (!line.empty() && line[0] != '#')
            num_vectors++;
    }
    infile.close();

    // Instantiate DUT
    Vrng_sync* dut = new Vrng_sync;

    // Initialize
    dut->clk     = 0;
    dut->rst_n   = 0;
    dut->valid_i = 0;
    dut->ready_i = 0;

    // Reset: 2 cycles low
    for (int i = 0; i < 4; i++) {
        dut->clk = 1; main_time += 5; dut->eval();
        dut->clk = 0; main_time += 5; dut->eval();
    }
    dut->rst_n   = 1;
    dut->ready_i = 1;

    // Generate vectors
    for (int n = 0; n < num_vectors; n++) {
        // Drive valid_i and posedge → LFSR advances, valid_o→1
        dut->valid_i = 1;
        dut->clk = 1; main_time += 5; dut->eval();
        dut->clk = 0; main_time += 5; dut->eval();
        dut->valid_i = 0;

        // Posedge to consume → valid_o→0
        dut->clk = 1; main_time += 5; dut->eval();
        // Print 256-bit result (8 × 32-bit words, MSB first)
        printf("RESULT: %08X%08X%08X%08X%08X%08X%08X%08X\n",
               dut->data_o[7], dut->data_o[6], dut->data_o[5], dut->data_o[4],
               dut->data_o[3], dut->data_o[2], dut->data_o[1], dut->data_o[0]);
        dut->clk = 0; main_time += 5; dut->eval();
    }

    delete dut;
    return 0;
}
