Mixed-language logging

This runnable example combines C++ testbench messages with diagnostics authored inside the RTL. Both enter the same sink and optional LogHistory, receive one per-test sequence, and retain their source language and source location.

make cpp-dpi-mixed-logging-run
make cpp-dpi-mixed-logging-output-test
make cpp-dpi-mixed-logging-sv-run

cpptb build adds the SV package, DPI bridge, include path, and CPPTB_ENABLE_SV_LOGGING define automatically. Users author only the testbench and the guarded logging calls.

C++ testbench

Task<void> mixed_language_logging(Dut dut, TestContext& test) {
    auto log = test.logger("cpp.driver");
    log.info("starting mixed-language traffic");

    dut.clk.set_now(0);
    test.start_clock(dut.clk, 10_ns);
    dut.rst_n.set(0);
    dut.valid.set(0);
    dut.data.set(0);
    co_await clock_cycles(dut.clk, 2);
    dut.rst_n.set(1);

    for (uint32_t index = 0; index < 2; ++index) {
        co_await RisingEdge{dut.clk};
        dut.data.set(0x1234'0000u + index);
        dut.valid.set(1);
        co_await RisingEdge{dut.clk};
        co_await ReadOnly{};
        test.expect_eq("accepted count", dut.accepted_count.get(), index + 1);
        log.info([&] {
            return "observed accepted count=" + std::to_string(index + 1);
        });
        co_await NextTimeStep{};
        dut.valid.set(0);
    }
}

Instrumented SystemVerilog

`ifdef CPPTB_ENABLE_SV_LOGGING
`include "cpptb/sv/cpptb_log.svh"
`endif

always_ff @(posedge clk or negedge rst_n) begin
  if (!rst_n) begin
    accepted_count <= '0;
  end else if (valid) begin
    accepted_count <= accepted_count + 1'b1;
`ifdef CPPTB_ENABLE_SV_LOGGING
    `cpptb_info($sformatf("accepted data=0x%08x", data), "request_monitor")
`endif
  end
end

The output checker asserts that all five records have contiguous sequence numbers, the two RTL records have SystemVerilog origin plus file, line, scope, and hierarchy metadata, and the three C++ records retain C++ source locations. The standalone pure-SV twin drives the same two transfers and checks the same counter results.

See Structured logging for filtering, origin semantics, custom sinks, and the distinction from ordinary $display.