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// DESCRIPTION: Verilator: Verilog Test module
//
// Copyright 2018 by Wilson Snyder. This program is free software; you can
// redistribute it and/or modify it under the terms of either the GNU
// Lesser General Public License Version 3 or the Perl Artistic License
// Version 2.0.
// SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
import "DPI-C" dpii_sys_task = function void \$dpii_sys ();
import "DPI-C" dpii_failure = function int \$dpii_failure ();
module t (clk);
input clk;
integer cyc;
integer failure;
initial cyc = 0;
`ifndef verilator
`error "Only Verilator supports PLI-ish DPI calls."
`endif
always @ (posedge clk) begin
if (cyc == 2) begin
failure = $dpii_failure();
$write("* failure = %0d\n", failure);
if (failure > 0) begin
$stop;
end
$write("*-* All Finished *-*\n");
$finish;
end
cyc <= cyc + 1;
end
// The purpose of this test is to confirm that the DPI-call serialization
// code in V3Partition does ensure that these DPI calls do not run
// concurrently.
//
// Alternatively, the test may be run with "--threads-dpi all" in which case
// it should confirm that the calls do run concurrently and do detect a
// collision (they should, if the test is set up right.) This is
// t_dpi_threads_collide.py.
//
// Q) Is it a risk that the partitioner will merge or serialize these always
// blocks, just by luck, even if the DPI-call serialization code fails?
//
// A) Yes, that's why t_dpi_threads_collide.py also passes
// --no-threads-do-coaren to disable MTask coarsening. This ensures that
// the MTask graph at the end of FixDataHazards (where we resolve DPI
// hazards) is basically the final MTasks graph, and that data hazards
// which persist beyond FixDataHazards should persist in the final
// generated C code.
always @ (posedge clk) begin
$dpii_sys();
end
always @ (posedge clk) begin
$dpii_sys();
end
endmodule
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