{ "dataset_id": "D3", "title": "HDL simulator observations: thirty original fixtures", "version": "2026-10-24-p6", "licence": "CC-BY-4.0", "licence_url": "https://creativecommons.org/licenses/by/4.0/", "attribution": "HDL simulator observations \u2014 original compilation, 2026-10-24", "fixture_count": 30, "tool_count": 2, "pipeline_count": 60, "executions_including_repeat": 120, "execution_environment": { "os": "macOS 27.0.1 build 26A434", "architecture": "arm64", "compiler": "Apple clang version 21.0.0 (clang-2100.3.34.2)", "local_date": "2026-10-24", "tools": { "icarus": "Icarus Verilog 13.0 stable v13_0", "verilator": "Verilator 5.052 2026-09-05 rev vUNKNOWN-built20260905" }, "configuration": { "icarus": [ "-g2012", "-gstrict-expr-width", "-Wall" ], "verilator": [ "--timing", "--language 1800-2012", "--x-assign 0", "--x-initial 0", "-Wno-fatal" ], "purpose": "Declared configurations, not defaults or language conformance verdicts." } }, "summary": { "compiled": 60, "executed": 60, "repeat_payloads_equal": 60, "matching_fixture_payloads": 20, "different_fixture_payloads": 10, "different_fixture_ids": [ "F01", "F02", "F13", "F14", "F15", "F16", "F18", "F19", "F29", "F30" ], "compile_warning_pipeline_count": 3 }, "comparison_rule": "Compare only literal lines beginning OBS. Full literal stdout/stderr and return codes remain in every observation; finish banners are not normalized into semantic differences.", "seed_scope": "F28 is an explicit portable modulo-arithmetic sequence. F29/F30 pin built-in seeds but do not assume matching algorithms across tools.", "rows": [ { "id": "F01", "title": "Explicit unknown assignment", "category": "four-state", "source": "harness/hdl-simulator-observations/fixtures/F01.sv", "source_sha256": "0aff1f827d4027a3be001c9989386f2f8229ae1162083ac9326bda99c1aba444", "origin": "Original project-authored fixture; first five concepts extend earlier original project fixtures.", "observations": { "icarus": { "tool_version": "13.0 stable v13_0", "compile_command": [ "iverilog", "-B", "${ICARUS_LIB}", "-g2012", "-gstrict-expr-width", "-Wall", "-s", "tb", "-o", "run.vvp", "fixture.sv" ], "execute_command": [ "vvp", "-M", "${ICARUS_LIB}", "run.vvp" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS value=10x1 unknown=1\nfixture.sv:7: $finish called at 1000 (1ps)\n", "runtime_stderr": "", "observed_lines": [ "OBS value=10x1 unknown=1" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:32:59.013749+00:00", "log": "harness/hdl-simulator-observations/logs/F01-icarus.json" }, "verilator": { "tool_version": "5.052 2026-09-05 rev vUNKNOWN-built20260905", "compile_command": [ "verilator", "--binary", "--timing", "--language", "1800-2012", "--x-assign", "0", "--x-initial", "0", "-Wno-fatal", "--quiet-build", "--quiet-stats", "--quiet-exit", "--top-module", "tb", "--Mdir", "obj", "fixture.sv" ], "execute_command": [ "./obj/Vtb", "+verilator+quiet" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS value=1001 unknown=0\n- fixture.sv:7: Verilog $finish\n", "runtime_stderr": "", "observed_lines": [ "OBS value=1001 unknown=0" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:33:08.563729+00:00", "log": "harness/hdl-simulator-observations/logs/F01-verilator.json" } }, "observed_payload_equal": false, "interpretation": "Unknown or initialization behavior differs under the declared Verilator zero policies and Icarus four-state representation.", "public_source_path": "/data/hdl-simulator-observations/fixtures/F01.sv" }, { "id": "F02", "title": "Uninitialized register", "category": "initialization", "source": "harness/hdl-simulator-observations/fixtures/F02.sv", "source_sha256": "8803165c30ab4298001506d849867f3711ea5d0bc2a7aeb2faf5a8cdc6600d1a", "origin": "Original project-authored fixture; first five concepts extend earlier original project fixtures.", "observations": { "icarus": { "tool_version": "13.0 stable v13_0", "compile_command": [ "iverilog", "-B", "${ICARUS_LIB}", "-g2012", "-gstrict-expr-width", "-Wall", "-s", "tb", "-o", "run.vvp", "fixture.sv" ], "execute_command": [ "vvp", "-M", "${ICARUS_LIB}", "run.vvp" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS value=xxxxxxxx unknown=1\nfixture.sv:7: $finish called at 1000 (1ps)\n", "runtime_stderr": "", "observed_lines": [ "OBS value=xxxxxxxx unknown=1" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:32:59.055145+00:00", "log": "harness/hdl-simulator-observations/logs/F02-icarus.json" }, "verilator": { "tool_version": "5.052 2026-09-05 rev vUNKNOWN-built20260905", "compile_command": [ "verilator", "--binary", "--timing", "--language", "1800-2012", "--x-assign", "0", "--x-initial", "0", "-Wno-fatal", "--quiet-build", "--quiet-stats", "--quiet-exit", "--top-module", "tb", "--Mdir", "obj", "fixture.sv" ], "execute_command": [ "./obj/Vtb", "+verilator+quiet" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS value=00000000 unknown=0\n- fixture.sv:7: Verilog $finish\n", "runtime_stderr": "", "observed_lines": [ "OBS value=00000000 unknown=0" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:33:08.565556+00:00", "log": "harness/hdl-simulator-observations/logs/F02-verilator.json" } }, "observed_payload_equal": false, "interpretation": "Unknown or initialization behavior differs under the declared Verilator zero policies and Icarus four-state representation.", "public_source_path": "/data/hdl-simulator-observations/fixtures/F02.sv" }, { "id": "F03", "title": "Mixed signed comparison", "category": "signedness", "source": "harness/hdl-simulator-observations/fixtures/F03.sv", "source_sha256": "92a19e3cef2946572ca028201862dc453d767e7dd95e5c938d49b2e313ad1679", "origin": "Original project-authored fixture; first five concepts extend earlier original project fixtures.", "observations": { "icarus": { "tool_version": "13.0 stable v13_0", "compile_command": [ "iverilog", "-B", "${ICARUS_LIB}", "-g2012", "-gstrict-expr-width", "-Wall", "-s", "tb", "-o", "run.vvp", "fixture.sv" ], "execute_command": [ "vvp", "-M", "${ICARUS_LIB}", "run.vvp" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS mixed_less=0 cast_less=1\nfixture.sv:7: $finish called at 1000 (1ps)\n", "runtime_stderr": "", "observed_lines": [ "OBS mixed_less=0 cast_less=1" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:33:08.617340+00:00", "log": "harness/hdl-simulator-observations/logs/F03-icarus.json" }, "verilator": { "tool_version": "5.052 2026-09-05 rev vUNKNOWN-built20260905", "compile_command": [ "verilator", "--binary", "--timing", "--language", "1800-2012", "--x-assign", "0", "--x-initial", "0", "-Wno-fatal", "--quiet-build", "--quiet-stats", "--quiet-exit", "--top-module", "tb", "--Mdir", "obj", "fixture.sv" ], "execute_command": [ "./obj/Vtb", "+verilator+quiet" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS mixed_less=0 cast_less=1\n- fixture.sv:7: Verilog $finish\n", "runtime_stderr": "", "observed_lines": [ "OBS mixed_less=0 cast_less=1" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:33:15.480575+00:00", "log": "harness/hdl-simulator-observations/logs/F03-verilator.json" } }, "observed_payload_equal": true, "interpretation": "Matching OBS payload in these configurations; finish banners and diagnostics are compared separately.", "public_source_path": "/data/hdl-simulator-observations/fixtures/F03.sv" }, { "id": "F04", "title": "Assignment-width truncation", "category": "width", "source": "harness/hdl-simulator-observations/fixtures/F04.sv", "source_sha256": "a14d8794cf0adc49a579a9f7e222f9bcd956088bec32763aeed2be0751a2be6c", "origin": "Original project-authored fixture; first five concepts extend earlier original project fixtures.", "observations": { "icarus": { "tool_version": "13.0 stable v13_0", "compile_command": [ "iverilog", "-B", "${ICARUS_LIB}", "-g2012", "-gstrict-expr-width", "-Wall", "-s", "tb", "-o", "run.vvp", "fixture.sv" ], "execute_command": [ "vvp", "-M", "${ICARUS_LIB}", "run.vvp" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS narrow=1 wide=17\nfixture.sv:7: $finish called at 1000 (1ps)\n", "runtime_stderr": "", "observed_lines": [ "OBS narrow=1 wide=17" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:33:08.673077+00:00", "log": "harness/hdl-simulator-observations/logs/F04-icarus.json" }, "verilator": { "tool_version": "5.052 2026-09-05 rev vUNKNOWN-built20260905", "compile_command": [ "verilator", "--binary", "--timing", "--language", "1800-2012", "--x-assign", "0", "--x-initial", "0", "-Wno-fatal", "--quiet-build", "--quiet-stats", "--quiet-exit", "--top-module", "tb", "--Mdir", "obj", "fixture.sv" ], "execute_command": [ "./obj/Vtb", "+verilator+quiet" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS narrow=1 wide=17\n- fixture.sv:7: Verilog $finish\n", "runtime_stderr": "", "observed_lines": [ "OBS narrow=1 wide=17" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:33:15.579529+00:00", "log": "harness/hdl-simulator-observations/logs/F04-verilator.json" } }, "observed_payload_equal": true, "interpretation": "Matching OBS payload in these configurations; finish banners and diagnostics are compared separately.", "public_source_path": "/data/hdl-simulator-observations/fixtures/F04.sv" }, { "id": "F05", "title": "Clocked nonblocking update", "category": "ordering", "source": "harness/hdl-simulator-observations/fixtures/F05.sv", "source_sha256": "c355074c07707bcf6b2c0ab149ebd365ee5e68e0ee1e118930ef3856b0e07efd", "origin": "Original project-authored fixture; first five concepts extend earlier original project fixtures.", "observations": { "icarus": { "tool_version": "13.0 stable v13_0", "compile_command": [ "iverilog", "-B", "${ICARUS_LIB}", "-g2012", "-gstrict-expr-width", "-Wall", "-s", "tb", "-o", "run.vvp", "fixture.sv" ], "execute_command": [ "vvp", "-M", "${ICARUS_LIB}", "run.vvp" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS a=1 b=0\nfixture.sv:8: $finish called at 6000 (1ps)\n", "runtime_stderr": "", "observed_lines": [ "OBS a=1 b=0" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:33:15.520381+00:00", "log": "harness/hdl-simulator-observations/logs/F05-icarus.json" }, "verilator": { "tool_version": "5.052 2026-09-05 rev vUNKNOWN-built20260905", "compile_command": [ "verilator", "--binary", "--timing", "--language", "1800-2012", "--x-assign", "0", "--x-initial", "0", "-Wno-fatal", "--quiet-build", "--quiet-stats", "--quiet-exit", "--top-module", "tb", "--Mdir", "obj", "fixture.sv" ], "execute_command": [ "./obj/Vtb", "+verilator+quiet" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS a=1 b=0\n- fixture.sv:8: Verilog $finish\n", "runtime_stderr": "", "observed_lines": [ "OBS a=1 b=0" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:33:24.579217+00:00", "log": "harness/hdl-simulator-observations/logs/F05-verilator.json" } }, "observed_payload_equal": true, "interpretation": "Matching OBS payload in these configurations; finish banners and diagnostics are compared separately.", "public_source_path": "/data/hdl-simulator-observations/fixtures/F05.sv" }, { "id": "F06", "title": "Signed extension", "category": "signedness", "source": "harness/hdl-simulator-observations/fixtures/F06.sv", "source_sha256": "743ce75b82f46170c6a034f3fb0ac4c5d55253c536586b781614b4f24c379831", "origin": "Original fixture authored for P6.", "observations": { "icarus": { "tool_version": "13.0 stable v13_0", "compile_command": [ "iverilog", "-B", "${ICARUS_LIB}", "-g2012", "-gstrict-expr-width", "-Wall", "-s", "tb", "-o", "run.vvp", "fixture.sv" ], "execute_command": [ "vvp", "-M", "${ICARUS_LIB}", "run.vvp" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS a=-8 b=-8 bits=fff8\nfixture.sv:7: $finish called at 1000 (1ps)\n", "runtime_stderr": "", "observed_lines": [ "OBS a=-8 b=-8 bits=fff8" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:33:15.615637+00:00", "log": "harness/hdl-simulator-observations/logs/F06-icarus.json" }, "verilator": { "tool_version": "5.052 2026-09-05 rev vUNKNOWN-built20260905", "compile_command": [ "verilator", "--binary", "--timing", "--language", "1800-2012", "--x-assign", "0", "--x-initial", "0", "-Wno-fatal", "--quiet-build", "--quiet-stats", "--quiet-exit", "--top-module", "tb", "--Mdir", "obj", "fixture.sv" ], "execute_command": [ "./obj/Vtb", "+verilator+quiet" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "%Warning-WIDTHEXPAND: fixture.sv:6:12: Operator ASSIGN expects 16 bits on the Assign RHS, but Assign RHS's VARREF 'a' generates 8 bits.\n : ... note: In instance 'tb'\n 6 | a=-8; b=a; #1; $display(\"OBS a=%0d b=%0d bits=%h\",a,b,b);\n | ^\n ... For warning description see https://verilator.org/warn/WIDTHEXPAND?v=5.052\n ... Use \"/* verilator lint_off WIDTHEXPAND */\" and lint_on around source to disable this message.\n", "runtime_stdout": "OBS a=-8 b=-8 bits=fff8\n- fixture.sv:7: Verilog $finish\n", "runtime_stderr": "", "observed_lines": [ "OBS a=-8 b=-8 bits=fff8" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:33:24.629802+00:00", "log": "harness/hdl-simulator-observations/logs/F06-verilator.json" } }, "observed_payload_equal": true, "interpretation": "Matching OBS payload in these configurations; finish banners and diagnostics are compared separately.", "public_source_path": "/data/hdl-simulator-observations/fixtures/F06.sv" }, { "id": "F07", "title": "Unsigned extension", "category": "signedness", "source": "harness/hdl-simulator-observations/fixtures/F07.sv", "source_sha256": "2975eec2dba42312e02813fcd81687278328a81cbbe247c133b35f9322cd60d9", "origin": "Original fixture authored for P6.", "observations": { "icarus": { "tool_version": "13.0 stable v13_0", "compile_command": [ "iverilog", "-B", "${ICARUS_LIB}", "-g2012", "-gstrict-expr-width", "-Wall", "-s", "tb", "-o", "run.vvp", "fixture.sv" ], "execute_command": [ "vvp", "-M", "${ICARUS_LIB}", "run.vvp" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS a=248 b=248 bits=00f8\nfixture.sv:7: $finish called at 1000 (1ps)\n", "runtime_stderr": "", "observed_lines": [ "OBS a=248 b=248 bits=00f8" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:33:24.627965+00:00", "log": "harness/hdl-simulator-observations/logs/F07-icarus.json" }, "verilator": { "tool_version": "5.052 2026-09-05 rev vUNKNOWN-built20260905", "compile_command": [ "verilator", "--binary", "--timing", "--language", "1800-2012", "--x-assign", "0", "--x-initial", "0", "-Wno-fatal", "--quiet-build", "--quiet-stats", "--quiet-exit", "--top-module", "tb", "--Mdir", "obj", "fixture.sv" ], "execute_command": [ "./obj/Vtb", "+verilator+quiet" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "%Warning-WIDTHEXPAND: fixture.sv:6:15: Operator ASSIGN expects 16 bits on the Assign RHS, but Assign RHS's VARREF 'a' generates 8 bits.\n : ... note: In instance 'tb'\n 6 | a=8'hf8; b=a; #1; $display(\"OBS a=%0d b=%0d bits=%h\",a,b,b);\n | ^\n ... For warning description see https://verilator.org/warn/WIDTHEXPAND?v=5.052\n ... Use \"/* verilator lint_off WIDTHEXPAND */\" and lint_on around source to disable this message.\n", "runtime_stdout": "OBS a=248 b=248 bits=00f8\n- fixture.sv:7: Verilog $finish\n", "runtime_stderr": "", "observed_lines": [ "OBS a=248 b=248 bits=00f8" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:33:32.437935+00:00", "log": "harness/hdl-simulator-observations/logs/F07-verilator.json" } }, "observed_payload_equal": true, "interpretation": "Matching OBS payload in these configurations; finish banners and diagnostics are compared separately.", "public_source_path": "/data/hdl-simulator-observations/fixtures/F07.sv" }, { "id": "F08", "title": "Logical and arithmetic shifts", "category": "signedness", "source": "harness/hdl-simulator-observations/fixtures/F08.sv", "source_sha256": "76fb8929d509eb5e91a9661266a2fa8b35f71490079d31706b628e3614676138", "origin": "Original fixture authored for P6.", "observations": { "icarus": { "tool_version": "13.0 stable v13_0", "compile_command": [ "iverilog", "-B", "${ICARUS_LIB}", "-g2012", "-gstrict-expr-width", "-Wall", "-s", "tb", "-o", "run.vvp", "fixture.sv" ], "execute_command": [ "vvp", "-M", "${ICARUS_LIB}", "run.vvp" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS logical=3c arithmetic=fc\nfixture.sv:7: $finish called at 1000 (1ps)\n", "runtime_stderr": "", "observed_lines": [ "OBS logical=3c arithmetic=fc" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:33:24.687993+00:00", "log": "harness/hdl-simulator-observations/logs/F08-icarus.json" }, "verilator": { "tool_version": "5.052 2026-09-05 rev vUNKNOWN-built20260905", "compile_command": [ "verilator", "--binary", "--timing", "--language", "1800-2012", "--x-assign", "0", "--x-initial", "0", "-Wno-fatal", "--quiet-build", "--quiet-stats", "--quiet-exit", "--top-module", "tb", "--Mdir", "obj", "fixture.sv" ], "execute_command": [ "./obj/Vtb", "+verilator+quiet" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS logical=3c arithmetic=fc\n- fixture.sv:7: Verilog $finish\n", "runtime_stderr": "", "observed_lines": [ "OBS logical=3c arithmetic=fc" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:33:32.436170+00:00", "log": "harness/hdl-simulator-observations/logs/F08-verilator.json" } }, "observed_payload_equal": true, "interpretation": "Matching OBS payload in these configurations; finish banners and diagnostics are compared separately.", "public_source_path": "/data/hdl-simulator-observations/fixtures/F08.sv" }, { "id": "F09", "title": "Unsized literal widths", "category": "width", "source": "harness/hdl-simulator-observations/fixtures/F09.sv", "source_sha256": "f7bb3ef047c2ef7b4021936d0eb665a748db0d00240613f543fd9f4076431c8e", "origin": "Original fixture authored for P6.", "observations": { "icarus": { "tool_version": "13.0 stable v13_0", "compile_command": [ "iverilog", "-B", "${ICARUS_LIB}", "-g2012", "-gstrict-expr-width", "-Wall", "-s", "tb", "-o", "run.vvp", "fixture.sv" ], "execute_command": [ "vvp", "-M", "${ICARUS_LIB}", "run.vvp" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS decimal_bits=32 hex_bits=32 value=1\nfixture.sv:7: $finish called at 1000 (1ps)\n", "runtime_stderr": "", "observed_lines": [ "OBS decimal_bits=32 hex_bits=32 value=1" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:33:32.486218+00:00", "log": "harness/hdl-simulator-observations/logs/F09-icarus.json" }, "verilator": { "tool_version": "5.052 2026-09-05 rev vUNKNOWN-built20260905", "compile_command": [ "verilator", "--binary", "--timing", "--language", "1800-2012", "--x-assign", "0", "--x-initial", "0", "-Wno-fatal", "--quiet-build", "--quiet-stats", "--quiet-exit", "--top-module", "tb", "--Mdir", "obj", "fixture.sv" ], "execute_command": [ "./obj/Vtb", "+verilator+quiet" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS decimal_bits=32 hex_bits=32 value=1\n- fixture.sv:7: Verilog $finish\n", "runtime_stderr": "", "observed_lines": [ "OBS decimal_bits=32 hex_bits=32 value=1" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:33:40.436349+00:00", "log": "harness/hdl-simulator-observations/logs/F09-verilator.json" } }, "observed_payload_equal": true, "interpretation": "Matching OBS payload in these configurations; finish banners and diagnostics are compared separately.", "public_source_path": "/data/hdl-simulator-observations/fixtures/F09.sv" }, { "id": "F10", "title": "Expression assignment context", "category": "width", "source": "harness/hdl-simulator-observations/fixtures/F10.sv", "source_sha256": "1c7dcbf188daa976f49977bb8ca0afbb5fb6b3b2f47317005be9276c7a1da5b0", "origin": "Original fixture authored for P6.", "observations": { "icarus": { "tool_version": "13.0 stable v13_0", "compile_command": [ "iverilog", "-B", "${ICARUS_LIB}", "-g2012", "-gstrict-expr-width", "-Wall", "-s", "tb", "-o", "run.vvp", "fixture.sv" ], "execute_command": [ "vvp", "-M", "${ICARUS_LIB}", "run.vvp" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS narrow=0 wide=16\nfixture.sv:7: $finish called at 1000 (1ps)\n", "runtime_stderr": "", "observed_lines": [ "OBS narrow=0 wide=16" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:33:32.540313+00:00", "log": "harness/hdl-simulator-observations/logs/F10-icarus.json" }, "verilator": { "tool_version": "5.052 2026-09-05 rev vUNKNOWN-built20260905", "compile_command": [ "verilator", "--binary", "--timing", "--language", "1800-2012", "--x-assign", "0", "--x-initial", "0", "-Wno-fatal", "--quiet-build", "--quiet-stats", "--quiet-exit", "--top-module", "tb", "--Mdir", "obj", "fixture.sv" ], "execute_command": [ "./obj/Vtb", "+verilator+quiet" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS narrow=0 wide=16\n- fixture.sv:7: Verilog $finish\n", "runtime_stderr": "", "observed_lines": [ "OBS narrow=0 wide=16" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:33:40.473444+00:00", "log": "harness/hdl-simulator-observations/logs/F10-verilator.json" } }, "observed_payload_equal": true, "interpretation": "Matching OBS payload in these configurations; finish banners and diagnostics are compared separately.", "public_source_path": "/data/hdl-simulator-observations/fixtures/F10.sv" }, { "id": "F11", "title": "Concatenation unsigned comparison", "category": "signedness", "source": "harness/hdl-simulator-observations/fixtures/F11.sv", "source_sha256": "d2e526eaed1907a17b8ddfdeb18095ff76c05783a5d59055e271633ef0a95bc7", "origin": "Original fixture authored for P6.", "observations": { "icarus": { "tool_version": "13.0 stable v13_0", "compile_command": [ "iverilog", "-B", "${ICARUS_LIB}", "-g2012", "-gstrict-expr-width", "-Wall", "-s", "tb", "-o", "run.vvp", "fixture.sv" ], "execute_command": [ "vvp", "-M", "${ICARUS_LIB}", "run.vvp" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS signed_less=1 concat_less=0\nfixture.sv:7: $finish called at 1000 (1ps)\n", "runtime_stderr": "", "observed_lines": [ "OBS signed_less=1 concat_less=0" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:33:40.481978+00:00", "log": "harness/hdl-simulator-observations/logs/F11-icarus.json" }, "verilator": { "tool_version": "5.052 2026-09-05 rev vUNKNOWN-built20260905", "compile_command": [ "verilator", "--binary", "--timing", "--language", "1800-2012", "--x-assign", "0", "--x-initial", "0", "-Wno-fatal", "--quiet-build", "--quiet-stats", "--quiet-exit", "--top-module", "tb", "--Mdir", "obj", "fixture.sv" ], "execute_command": [ "./obj/Vtb", "+verilator+quiet" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "%Warning-UNSIGNED: fixture.sv:6:69: Comparison is constant due to unsigned arithmetic\n : ... note: In instance 'tb'\n 6 | a=-1; #1; $display(\"OBS signed_less=%0d concat_less=%0d\",a<0,{a}<0);\n | ^\n ... For warning description see https://verilator.org/warn/UNSIGNED?v=5.052\n ... Use \"/* verilator lint_off UNSIGNED */\" and lint_on around source to disable this message.\n", "runtime_stdout": "OBS signed_less=1 concat_less=0\n- fixture.sv:7: Verilog $finish\n", "runtime_stderr": "", "observed_lines": [ "OBS signed_less=1 concat_less=0" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:33:48.246740+00:00", "log": "harness/hdl-simulator-observations/logs/F11-verilator.json" } }, "observed_payload_equal": true, "interpretation": "Matching OBS payload in these configurations; finish banners and diagnostics are compared separately.", "public_source_path": "/data/hdl-simulator-observations/fixtures/F11.sv" }, { "id": "F12", "title": "Explicit signed cast", "category": "signedness", "source": "harness/hdl-simulator-observations/fixtures/F12.sv", "source_sha256": "b0bc235dc7777b9b6e1839efc2242060e70a089ef0dee27b67bdf3ceedcb1953", "origin": "Original fixture authored for P6.", "observations": { "icarus": { "tool_version": "13.0 stable v13_0", "compile_command": [ "iverilog", "-B", "${ICARUS_LIB}", "-g2012", "-gstrict-expr-width", "-Wall", "-s", "tb", "-o", "run.vvp", "fixture.sv" ], "execute_command": [ "vvp", "-M", "${ICARUS_LIB}", "run.vvp" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS unsigned=255 signed=-1\nfixture.sv:7: $finish called at 1000 (1ps)\n", "runtime_stderr": "", "observed_lines": [ "OBS unsigned=255 signed=-1" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:33:40.534576+00:00", "log": "harness/hdl-simulator-observations/logs/F12-icarus.json" }, "verilator": { "tool_version": "5.052 2026-09-05 rev vUNKNOWN-built20260905", "compile_command": [ "verilator", "--binary", "--timing", "--language", "1800-2012", "--x-assign", "0", "--x-initial", "0", "-Wno-fatal", "--quiet-build", "--quiet-stats", "--quiet-exit", "--top-module", "tb", "--Mdir", "obj", "fixture.sv" ], "execute_command": [ "./obj/Vtb", "+verilator+quiet" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS unsigned=255 signed=-1\n- fixture.sv:7: Verilog $finish\n", "runtime_stderr": "", "observed_lines": [ "OBS unsigned=255 signed=-1" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:33:48.385237+00:00", "log": "harness/hdl-simulator-observations/logs/F12-verilator.json" } }, "observed_payload_equal": true, "interpretation": "Matching OBS payload in these configurations; finish banners and diagnostics are compared separately.", "public_source_path": "/data/hdl-simulator-observations/fixtures/F12.sv" }, { "id": "F13", "title": "Unknown condition in if", "category": "four-state", "source": "harness/hdl-simulator-observations/fixtures/F13.sv", "source_sha256": "3e85a4a1f7884bcf1f1f9d902b2a320e6aa9cf54bfca1040ff77a44f1aa1abb4", "origin": "Original fixture authored for P6.", "observations": { "icarus": { "tool_version": "13.0 stable v13_0", "compile_command": [ "iverilog", "-B", "${ICARUS_LIB}", "-g2012", "-gstrict-expr-width", "-Wall", "-s", "tb", "-o", "run.vvp", "fixture.sv" ], "execute_command": [ "vvp", "-M", "${ICARUS_LIB}", "run.vvp" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS sel=x branch=2\nfixture.sv:7: $finish called at 1000 (1ps)\n", "runtime_stderr": "", "observed_lines": [ "OBS sel=x branch=2" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:33:48.294444+00:00", "log": "harness/hdl-simulator-observations/logs/F13-icarus.json" }, "verilator": { "tool_version": "5.052 2026-09-05 rev vUNKNOWN-built20260905", "compile_command": [ "verilator", "--binary", "--timing", "--language", "1800-2012", "--x-assign", "0", "--x-initial", "0", "-Wno-fatal", "--quiet-build", "--quiet-stats", "--quiet-exit", "--top-module", "tb", "--Mdir", "obj", "fixture.sv" ], "execute_command": [ "./obj/Vtb", "+verilator+quiet" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS sel=0 branch=2\n- fixture.sv:7: Verilog $finish\n", "runtime_stderr": "", "observed_lines": [ "OBS sel=0 branch=2" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:33:54.989274+00:00", "log": "harness/hdl-simulator-observations/logs/F13-verilator.json" } }, "observed_payload_equal": false, "interpretation": "Unknown or initialization behavior differs under the declared Verilator zero policies and Icarus four-state representation.", "public_source_path": "/data/hdl-simulator-observations/fixtures/F13.sv" }, { "id": "F14", "title": "Unknown conditional bit merge", "category": "four-state", "source": "harness/hdl-simulator-observations/fixtures/F14.sv", "source_sha256": "e0101f0529a119e45821b434c148b25cab2554419f49d19e57a25013a39361a8", "origin": "Original fixture authored for P6.", "observations": { "icarus": { "tool_version": "13.0 stable v13_0", "compile_command": [ "iverilog", "-B", "${ICARUS_LIB}", "-g2012", "-gstrict-expr-width", "-Wall", "-s", "tb", "-o", "run.vvp", "fixture.sv" ], "execute_command": [ "vvp", "-M", "${ICARUS_LIB}", "run.vvp" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS value=10xx\nfixture.sv:7: $finish called at 1000 (1ps)\n", "runtime_stderr": "", "observed_lines": [ "OBS value=10xx" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:33:48.425701+00:00", "log": "harness/hdl-simulator-observations/logs/F14-icarus.json" }, "verilator": { "tool_version": "5.052 2026-09-05 rev vUNKNOWN-built20260905", "compile_command": [ "verilator", "--binary", "--timing", "--language", "1800-2012", "--x-assign", "0", "--x-initial", "0", "-Wno-fatal", "--quiet-build", "--quiet-stats", "--quiet-exit", "--top-module", "tb", "--Mdir", "obj", "fixture.sv" ], "execute_command": [ "./obj/Vtb", "+verilator+quiet" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS value=1001\n- fixture.sv:7: Verilog $finish\n", "runtime_stderr": "", "observed_lines": [ "OBS value=1001" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:33:55.146251+00:00", "log": "harness/hdl-simulator-observations/logs/F14-verilator.json" } }, "observed_payload_equal": false, "interpretation": "Unknown or initialization behavior differs under the declared Verilator zero policies and Icarus four-state representation.", "public_source_path": "/data/hdl-simulator-observations/fixtures/F14.sv" }, { "id": "F15", "title": "Case equality against unknown", "category": "four-state", "source": "harness/hdl-simulator-observations/fixtures/F15.sv", "source_sha256": "78927603724403e8b85ea19cf4f23b5635348be2c09e7c30118bea79502c817f", "origin": "Original fixture authored for P6.", "observations": { "icarus": { "tool_version": "13.0 stable v13_0", "compile_command": [ "iverilog", "-B", "${ICARUS_LIB}", "-g2012", "-gstrict-expr-width", "-Wall", "-s", "tb", "-o", "run.vvp", "fixture.sv" ], "execute_command": [ "vvp", "-M", "${ICARUS_LIB}", "run.vvp" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS ordinary=x case_x=1 unknown=1\nfixture.sv:7: $finish called at 1000 (1ps)\n", "runtime_stderr": "", "observed_lines": [ "OBS ordinary=x case_x=1 unknown=1" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:33:55.039768+00:00", "log": "harness/hdl-simulator-observations/logs/F15-icarus.json" }, "verilator": { "tool_version": "5.052 2026-09-05 rev vUNKNOWN-built20260905", "compile_command": [ "verilator", "--binary", "--timing", "--language", "1800-2012", "--x-assign", "0", "--x-initial", "0", "-Wno-fatal", "--quiet-build", "--quiet-stats", "--quiet-exit", "--top-module", "tb", "--Mdir", "obj", "fixture.sv" ], "execute_command": [ "./obj/Vtb", "+verilator+quiet" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS ordinary=1 case_x=0 unknown=0\n- fixture.sv:7: Verilog $finish\n", "runtime_stderr": "", "observed_lines": [ "OBS ordinary=1 case_x=0 unknown=0" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:34:01.765707+00:00", "log": "harness/hdl-simulator-observations/logs/F15-verilator.json" } }, "observed_payload_equal": false, "interpretation": "Unknown or initialization behavior differs under the declared Verilator zero policies and Icarus four-state representation.", "public_source_path": "/data/hdl-simulator-observations/fixtures/F15.sv" }, { "id": "F16", "title": "Reduction with unknown bit", "category": "four-state", "source": "harness/hdl-simulator-observations/fixtures/F16.sv", "source_sha256": "87ffe117fc76c21bc10abdcec046cec858d15aa19b26431be4b4b7445d3debd3", "origin": "Original fixture authored for P6.", "observations": { "icarus": { "tool_version": "13.0 stable v13_0", "compile_command": [ "iverilog", "-B", "${ICARUS_LIB}", "-g2012", "-gstrict-expr-width", "-Wall", "-s", "tb", "-o", "run.vvp", "fixture.sv" ], "execute_command": [ "vvp", "-M", "${ICARUS_LIB}", "run.vvp" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS and=x or=1 xor=x\nfixture.sv:7: $finish called at 1000 (1ps)\n", "runtime_stderr": "", "observed_lines": [ "OBS and=x or=1 xor=x" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:33:55.181495+00:00", "log": "harness/hdl-simulator-observations/logs/F16-icarus.json" }, "verilator": { "tool_version": "5.052 2026-09-05 rev vUNKNOWN-built20260905", "compile_command": [ "verilator", "--binary", "--timing", "--language", "1800-2012", "--x-assign", "0", "--x-initial", "0", "-Wno-fatal", "--quiet-build", "--quiet-stats", "--quiet-exit", "--top-module", "tb", "--Mdir", "obj", "fixture.sv" ], "execute_command": [ "./obj/Vtb", "+verilator+quiet" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS and=0 or=1 xor=1\n- fixture.sv:7: Verilog $finish\n", "runtime_stderr": "", "observed_lines": [ "OBS and=0 or=1 xor=1" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:34:01.856809+00:00", "log": "harness/hdl-simulator-observations/logs/F16-verilator.json" } }, "observed_payload_equal": false, "interpretation": "Unknown or initialization behavior differs under the declared Verilator zero policies and Icarus four-state representation.", "public_source_path": "/data/hdl-simulator-observations/fixtures/F16.sv" }, { "id": "F17", "title": "Controlling bitwise zero", "category": "four-state", "source": "harness/hdl-simulator-observations/fixtures/F17.sv", "source_sha256": "e475976d33161df346eda9841a7d7852efbfeaea566e7d29f079301983cc2bf8", "origin": "Original fixture authored for P6.", "observations": { "icarus": { "tool_version": "13.0 stable v13_0", "compile_command": [ "iverilog", "-B", "${ICARUS_LIB}", "-g2012", "-gstrict-expr-width", "-Wall", "-s", "tb", "-o", "run.vvp", "fixture.sv" ], "execute_command": [ "vvp", "-M", "${ICARUS_LIB}", "run.vvp" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS x_and_0=0 x_or_1=1\nfixture.sv:7: $finish called at 1000 (1ps)\n", "runtime_stderr": "", "observed_lines": [ "OBS x_and_0=0 x_or_1=1" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:34:01.803639+00:00", "log": "harness/hdl-simulator-observations/logs/F17-icarus.json" }, "verilator": { "tool_version": "5.052 2026-09-05 rev vUNKNOWN-built20260905", "compile_command": [ "verilator", "--binary", "--timing", "--language", "1800-2012", "--x-assign", "0", "--x-initial", "0", "-Wno-fatal", "--quiet-build", "--quiet-stats", "--quiet-exit", "--top-module", "tb", "--Mdir", "obj", "fixture.sv" ], "execute_command": [ "./obj/Vtb", "+verilator+quiet" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS x_and_0=0 x_or_1=1\n- fixture.sv:7: Verilog $finish\n", "runtime_stderr": "", "observed_lines": [ "OBS x_and_0=0 x_or_1=1" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:34:08.258192+00:00", "log": "harness/hdl-simulator-observations/logs/F17-verilator.json" } }, "observed_payload_equal": true, "interpretation": "Matching OBS payload in these configurations; finish banners and diagnostics are compared separately.", "public_source_path": "/data/hdl-simulator-observations/fixtures/F17.sv" }, { "id": "F18", "title": "Unknown XOR operand", "category": "four-state", "source": "harness/hdl-simulator-observations/fixtures/F18.sv", "source_sha256": "5d83673ab342a8318fc02d2412afe3f5abbbfbdd601fbab4a05bddda8f2768a5", "origin": "Original fixture authored for P6.", "observations": { "icarus": { "tool_version": "13.0 stable v13_0", "compile_command": [ "iverilog", "-B", "${ICARUS_LIB}", "-g2012", "-gstrict-expr-width", "-Wall", "-s", "tb", "-o", "run.vvp", "fixture.sv" ], "execute_command": [ "vvp", "-M", "${ICARUS_LIB}", "run.vvp" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS x_xor_0=x\nfixture.sv:7: $finish called at 1000 (1ps)\n", "runtime_stderr": "", "observed_lines": [ "OBS x_xor_0=x" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:34:01.894927+00:00", "log": "harness/hdl-simulator-observations/logs/F18-icarus.json" }, "verilator": { "tool_version": "5.052 2026-09-05 rev vUNKNOWN-built20260905", "compile_command": [ "verilator", "--binary", "--timing", "--language", "1800-2012", "--x-assign", "0", "--x-initial", "0", "-Wno-fatal", "--quiet-build", "--quiet-stats", "--quiet-exit", "--top-module", "tb", "--Mdir", "obj", "fixture.sv" ], "execute_command": [ "./obj/Vtb", "+verilator+quiet" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS x_xor_0=0\n- fixture.sv:7: Verilog $finish\n", "runtime_stderr": "", "observed_lines": [ "OBS x_xor_0=0" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:34:08.352554+00:00", "log": "harness/hdl-simulator-observations/logs/F18-verilator.json" } }, "observed_payload_equal": false, "interpretation": "Unknown or initialization behavior differs under the declared Verilator zero policies and Icarus four-state representation.", "public_source_path": "/data/hdl-simulator-observations/fixtures/F18.sv" }, { "id": "F19", "title": "Two-state bit assignment", "category": "four-state", "source": "harness/hdl-simulator-observations/fixtures/F19.sv", "source_sha256": "2d48bdf32bd532b6413427d2360bac6099c56403b28de17b415a1b76f46cba35", "origin": "Original fixture authored for P6.", "observations": { "icarus": { "tool_version": "13.0 stable v13_0", "compile_command": [ "iverilog", "-B", "${ICARUS_LIB}", "-g2012", "-gstrict-expr-width", "-Wall", "-s", "tb", "-o", "run.vvp", "fixture.sv" ], "execute_command": [ "vvp", "-M", "${ICARUS_LIB}", "run.vvp" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS bit=0 logic=x\nfixture.sv:7: $finish called at 1000 (1ps)\n", "runtime_stderr": "", "observed_lines": [ "OBS bit=0 logic=x" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:34:08.296197+00:00", "log": "harness/hdl-simulator-observations/logs/F19-icarus.json" }, "verilator": { "tool_version": "5.052 2026-09-05 rev vUNKNOWN-built20260905", "compile_command": [ "verilator", "--binary", "--timing", "--language", "1800-2012", "--x-assign", "0", "--x-initial", "0", "-Wno-fatal", "--quiet-build", "--quiet-stats", "--quiet-exit", "--top-module", "tb", "--Mdir", "obj", "fixture.sv" ], "execute_command": [ "./obj/Vtb", "+verilator+quiet" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS bit=0 logic=0\n- fixture.sv:7: Verilog $finish\n", "runtime_stderr": "", "observed_lines": [ "OBS bit=0 logic=0" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:34:14.825460+00:00", "log": "harness/hdl-simulator-observations/logs/F19-verilator.json" } }, "observed_payload_equal": false, "interpretation": "Unknown or initialization behavior differs under the declared Verilator zero policies and Icarus four-state representation.", "public_source_path": "/data/hdl-simulator-observations/fixtures/F19.sv" }, { "id": "F20", "title": "Explicit register initialization", "category": "initialization", "source": "harness/hdl-simulator-observations/fixtures/F20.sv", "source_sha256": "a07aae4ba39a68e4d8853e70d1758a1b6676e0e4250737f414c3e49c42438279", "origin": "Original fixture authored for P6.", "observations": { "icarus": { "tool_version": "13.0 stable v13_0", "compile_command": [ "iverilog", "-B", "${ICARUS_LIB}", "-g2012", "-gstrict-expr-width", "-Wall", "-s", "tb", "-o", "run.vvp", "fixture.sv" ], "execute_command": [ "vvp", "-M", "${ICARUS_LIB}", "run.vvp" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS value=5a\nfixture.sv:7: $finish called at 1000 (1ps)\n", "runtime_stderr": "", "observed_lines": [ "OBS value=5a" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:34:08.386765+00:00", "log": "harness/hdl-simulator-observations/logs/F20-icarus.json" }, "verilator": { "tool_version": "5.052 2026-09-05 rev vUNKNOWN-built20260905", "compile_command": [ "verilator", "--binary", "--timing", "--language", "1800-2012", "--x-assign", "0", "--x-initial", "0", "-Wno-fatal", "--quiet-build", "--quiet-stats", "--quiet-exit", "--top-module", "tb", "--Mdir", "obj", "fixture.sv" ], "execute_command": [ "./obj/Vtb", "+verilator+quiet" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS value=5a\n- fixture.sv:7: Verilog $finish\n", "runtime_stderr": "", "observed_lines": [ "OBS value=5a" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:34:14.904042+00:00", "log": "harness/hdl-simulator-observations/logs/F20-verilator.json" } }, "observed_payload_equal": true, "interpretation": "Matching OBS payload in these configurations; finish banners and diagnostics are compared separately.", "public_source_path": "/data/hdl-simulator-observations/fixtures/F20.sv" }, { "id": "F21", "title": "Declaration initialization", "category": "initialization", "source": "harness/hdl-simulator-observations/fixtures/F21.sv", "source_sha256": "e72bd55204fd0927ced653f4dfeae5a8e9b5bd81375040abf2497ce913e1298f", "origin": "Original fixture authored for P6.", "observations": { "icarus": { "tool_version": "13.0 stable v13_0", "compile_command": [ "iverilog", "-B", "${ICARUS_LIB}", "-g2012", "-gstrict-expr-width", "-Wall", "-s", "tb", "-o", "run.vvp", "fixture.sv" ], "execute_command": [ "vvp", "-M", "${ICARUS_LIB}", "run.vvp" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS value=a5\nfixture.sv:7: $finish called at 1000 (1ps)\n", "runtime_stderr": "", "observed_lines": [ "OBS value=a5" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:34:14.861956+00:00", "log": "harness/hdl-simulator-observations/logs/F21-icarus.json" }, "verilator": { "tool_version": "5.052 2026-09-05 rev vUNKNOWN-built20260905", "compile_command": [ "verilator", "--binary", "--timing", "--language", "1800-2012", "--x-assign", "0", "--x-initial", "0", "-Wno-fatal", "--quiet-build", "--quiet-stats", "--quiet-exit", "--top-module", "tb", "--Mdir", "obj", "fixture.sv" ], "execute_command": [ "./obj/Vtb", "+verilator+quiet" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS value=a5\n- fixture.sv:7: Verilog $finish\n", "runtime_stderr": "", "observed_lines": [ "OBS value=a5" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:34:21.979088+00:00", "log": "harness/hdl-simulator-observations/logs/F21-verilator.json" } }, "observed_payload_equal": true, "interpretation": "Matching OBS payload in these configurations; finish banners and diagnostics are compared separately.", "public_source_path": "/data/hdl-simulator-observations/fixtures/F21.sv" }, { "id": "F22", "title": "Blocking statements in one process", "category": "ordering", "source": "harness/hdl-simulator-observations/fixtures/F22.sv", "source_sha256": "03c3754609871e44d06bc60435cd77246f75670e36b1b8bf4d40f5357ab2bec9", "origin": "Original fixture authored for P6.", "observations": { "icarus": { "tool_version": "13.0 stable v13_0", "compile_command": [ "iverilog", "-B", "${ICARUS_LIB}", "-g2012", "-gstrict-expr-width", "-Wall", "-s", "tb", "-o", "run.vvp", "fixture.sv" ], "execute_command": [ "vvp", "-M", "${ICARUS_LIB}", "run.vvp" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS a=2 b=2\nfixture.sv:7: $finish called at 1000 (1ps)\n", "runtime_stderr": "", "observed_lines": [ "OBS a=2 b=2" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:34:14.948105+00:00", "log": "harness/hdl-simulator-observations/logs/F22-icarus.json" }, "verilator": { "tool_version": "5.052 2026-09-05 rev vUNKNOWN-built20260905", "compile_command": [ "verilator", "--binary", "--timing", "--language", "1800-2012", "--x-assign", "0", "--x-initial", "0", "-Wno-fatal", "--quiet-build", "--quiet-stats", "--quiet-exit", "--top-module", "tb", "--Mdir", "obj", "fixture.sv" ], "execute_command": [ "./obj/Vtb", "+verilator+quiet" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS a=2 b=2\n- fixture.sv:7: Verilog $finish\n", "runtime_stderr": "", "observed_lines": [ "OBS a=2 b=2" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:34:22.050492+00:00", "log": "harness/hdl-simulator-observations/logs/F22-verilator.json" } }, "observed_payload_equal": true, "interpretation": "Matching OBS payload in these configurations; finish banners and diagnostics are compared separately.", "public_source_path": "/data/hdl-simulator-observations/fixtures/F22.sv" }, { "id": "F23", "title": "Nonblocking swap after edge", "category": "ordering", "source": "harness/hdl-simulator-observations/fixtures/F23.sv", "source_sha256": "ac5e085093e19074477c2675d4340505f30c5c9637dce88f70f6f67144ab7055", "origin": "Original fixture authored for P6.", "observations": { "icarus": { "tool_version": "13.0 stable v13_0", "compile_command": [ "iverilog", "-B", "${ICARUS_LIB}", "-g2012", "-gstrict-expr-width", "-Wall", "-s", "tb", "-o", "run.vvp", "fixture.sv" ], "execute_command": [ "vvp", "-M", "${ICARUS_LIB}", "run.vvp" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS a=2 b=1\nfixture.sv:8: $finish called at 6000 (1ps)\n", "runtime_stderr": "", "observed_lines": [ "OBS a=2 b=1" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:34:22.020930+00:00", "log": "harness/hdl-simulator-observations/logs/F23-icarus.json" }, "verilator": { "tool_version": "5.052 2026-09-05 rev vUNKNOWN-built20260905", "compile_command": [ "verilator", "--binary", "--timing", "--language", "1800-2012", "--x-assign", "0", "--x-initial", "0", "-Wno-fatal", "--quiet-build", "--quiet-stats", "--quiet-exit", "--top-module", "tb", "--Mdir", "obj", "fixture.sv" ], "execute_command": [ "./obj/Vtb", "+verilator+quiet" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS a=2 b=1\n- fixture.sv:8: Verilog $finish\n", "runtime_stderr": "", "observed_lines": [ "OBS a=2 b=1" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:34:28.780946+00:00", "log": "harness/hdl-simulator-observations/logs/F23-verilator.json" } }, "observed_payload_equal": true, "interpretation": "Matching OBS payload in these configurations; finish banners and diagnostics are compared separately.", "public_source_path": "/data/hdl-simulator-observations/fixtures/F23.sv" }, { "id": "F24", "title": "Last nonblocking assignment in process", "category": "ordering", "source": "harness/hdl-simulator-observations/fixtures/F24.sv", "source_sha256": "a6b86428c170c71e11c15105544b8a93477e8d9f256abbfe4e224aab0cf5233f", "origin": "Original fixture authored for P6.", "observations": { "icarus": { "tool_version": "13.0 stable v13_0", "compile_command": [ "iverilog", "-B", "${ICARUS_LIB}", "-g2012", "-gstrict-expr-width", "-Wall", "-s", "tb", "-o", "run.vvp", "fixture.sv" ], "execute_command": [ "vvp", "-M", "${ICARUS_LIB}", "run.vvp" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS a=2\nfixture.sv:8: $finish called at 6000 (1ps)\n", "runtime_stderr": "", "observed_lines": [ "OBS a=2" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:34:22.089038+00:00", "log": "harness/hdl-simulator-observations/logs/F24-icarus.json" }, "verilator": { "tool_version": "5.052 2026-09-05 rev vUNKNOWN-built20260905", "compile_command": [ "verilator", "--binary", "--timing", "--language", "1800-2012", "--x-assign", "0", "--x-initial", "0", "-Wno-fatal", "--quiet-build", "--quiet-stats", "--quiet-exit", "--top-module", "tb", "--Mdir", "obj", "fixture.sv" ], "execute_command": [ "./obj/Vtb", "+verilator+quiet" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS a=2\n- fixture.sv:8: Verilog $finish\n", "runtime_stderr": "", "observed_lines": [ "OBS a=2" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:34:28.982057+00:00", "log": "harness/hdl-simulator-observations/logs/F24-verilator.json" } }, "observed_payload_equal": true, "interpretation": "Matching OBS payload in these configurations; finish banners and diagnostics are compared separately.", "public_source_path": "/data/hdl-simulator-observations/fixtures/F24.sv" }, { "id": "F25", "title": "Three-stage pipeline", "category": "ordering", "source": "harness/hdl-simulator-observations/fixtures/F25.sv", "source_sha256": "c1021e94d67e5edaacd3c02d6b9b8128d56fe309cb767e07693e15c4bbda14f3", "origin": "Original fixture authored for P6.", "observations": { "icarus": { "tool_version": "13.0 stable v13_0", "compile_command": [ "iverilog", "-B", "${ICARUS_LIB}", "-g2012", "-gstrict-expr-width", "-Wall", "-s", "tb", "-o", "run.vvp", "fixture.sv" ], "execute_command": [ "vvp", "-M", "${ICARUS_LIB}", "run.vvp" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS a=1 b=0 c=0\nOBS a=2 b=1 c=0\nOBS a=3 b=2 c=1\nfixture.sv:8: $finish called at 30000 (1ps)\n", "runtime_stderr": "", "observed_lines": [ "OBS a=1 b=0 c=0", "OBS a=2 b=1 c=0", "OBS a=3 b=2 c=1" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:34:28.820531+00:00", "log": "harness/hdl-simulator-observations/logs/F25-icarus.json" }, "verilator": { "tool_version": "5.052 2026-09-05 rev vUNKNOWN-built20260905", "compile_command": [ "verilator", "--binary", "--timing", "--language", "1800-2012", "--x-assign", "0", "--x-initial", "0", "-Wno-fatal", "--quiet-build", "--quiet-stats", "--quiet-exit", "--top-module", "tb", "--Mdir", "obj", "fixture.sv" ], "execute_command": [ "./obj/Vtb", "+verilator+quiet" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS a=1 b=0 c=0\nOBS a=2 b=1 c=0\nOBS a=3 b=2 c=1\n- fixture.sv:8: Verilog $finish\n", "runtime_stderr": "", "observed_lines": [ "OBS a=1 b=0 c=0", "OBS a=2 b=1 c=0", "OBS a=3 b=2 c=1" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:34:35.595079+00:00", "log": "harness/hdl-simulator-observations/logs/F25-verilator.json" } }, "observed_payload_equal": true, "interpretation": "Matching OBS payload in these configurations; finish banners and diagnostics are compared separately.", "public_source_path": "/data/hdl-simulator-observations/fixtures/F25.sv" }, { "id": "F26", "title": "Opposite-edge stimulus", "category": "ordering", "source": "harness/hdl-simulator-observations/fixtures/F26.sv", "source_sha256": "347f5ea6289e2505fd39f577011d62971b567703088bb4319143728a1f713388", "origin": "Original fixture authored for P6.", "observations": { "icarus": { "tool_version": "13.0 stable v13_0", "compile_command": [ "iverilog", "-B", "${ICARUS_LIB}", "-g2012", "-gstrict-expr-width", "-Wall", "-s", "tb", "-o", "run.vvp", "fixture.sv" ], "execute_command": [ "vvp", "-M", "${ICARUS_LIB}", "run.vvp" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS d=1 q=1\nfixture.sv:9: $finish called at 16000 (1ps)\n", "runtime_stderr": "", "observed_lines": [ "OBS d=1 q=1" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:34:29.020620+00:00", "log": "harness/hdl-simulator-observations/logs/F26-icarus.json" }, "verilator": { "tool_version": "5.052 2026-09-05 rev vUNKNOWN-built20260905", "compile_command": [ "verilator", "--binary", "--timing", "--language", "1800-2012", "--x-assign", "0", "--x-initial", "0", "-Wno-fatal", "--quiet-build", "--quiet-stats", "--quiet-exit", "--top-module", "tb", "--Mdir", "obj", "fixture.sv" ], "execute_command": [ "./obj/Vtb", "+verilator+quiet" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS d=1 q=1\n- fixture.sv:9: Verilog $finish\n", "runtime_stderr": "", "observed_lines": [ "OBS d=1 q=1" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:34:35.867616+00:00", "log": "harness/hdl-simulator-observations/logs/F26-verilator.json" } }, "observed_payload_equal": true, "interpretation": "Matching OBS payload in these configurations; finish banners and diagnostics are compared separately.", "public_source_path": "/data/hdl-simulator-observations/fixtures/F26.sv" }, { "id": "F27", "title": "Asynchronous reset then clock", "category": "initialization", "source": "harness/hdl-simulator-observations/fixtures/F27.sv", "source_sha256": "0a67367fb1e012f52b0017c00b810605f9702f89def4b50e9abef78e9aad0881", "origin": "Original fixture authored for P6.", "observations": { "icarus": { "tool_version": "13.0 stable v13_0", "compile_command": [ "iverilog", "-B", "${ICARUS_LIB}", "-g2012", "-gstrict-expr-width", "-Wall", "-s", "tb", "-o", "run.vvp", "fixture.sv" ], "execute_command": [ "vvp", "-M", "${ICARUS_LIB}", "run.vvp" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS reset_q=0\nOBS clock_q=1\nfixture.sv:8: $finish called at 6000 (1ps)\n", "runtime_stderr": "", "observed_lines": [ "OBS reset_q=0", "OBS clock_q=1" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:34:35.636914+00:00", "log": "harness/hdl-simulator-observations/logs/F27-icarus.json" }, "verilator": { "tool_version": "5.052 2026-09-05 rev vUNKNOWN-built20260905", "compile_command": [ "verilator", "--binary", "--timing", "--language", "1800-2012", "--x-assign", "0", "--x-initial", "0", "-Wno-fatal", "--quiet-build", "--quiet-stats", "--quiet-exit", "--top-module", "tb", "--Mdir", "obj", "fixture.sv" ], "execute_command": [ "./obj/Vtb", "+verilator+quiet" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS reset_q=0\nOBS clock_q=1\n- fixture.sv:8: Verilog $finish\n", "runtime_stderr": "", "observed_lines": [ "OBS reset_q=0", "OBS clock_q=1" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:34:42.172968+00:00", "log": "harness/hdl-simulator-observations/logs/F27-verilator.json" } }, "observed_payload_equal": true, "interpretation": "Matching OBS payload in these configurations; finish banners and diagnostics are compared separately.", "public_source_path": "/data/hdl-simulator-observations/fixtures/F27.sv" }, { "id": "F28", "title": "Explicit modulo arithmetic sequence", "category": "seed", "source": "harness/hdl-simulator-observations/fixtures/F28.sv", "source_sha256": "f4a2d780509909502456575bd2c896a6702351ac19867a85ab9f3091eeaf6d46", "origin": "Original fixture authored for P6.", "observations": { "icarus": { "tool_version": "13.0 stable v13_0", "compile_command": [ "iverilog", "-B", "${ICARUS_LIB}", "-g2012", "-gstrict-expr-width", "-Wall", "-s", "tb", "-o", "run.vvp", "fixture.sv" ], "execute_command": [ "vvp", "-M", "${ICARUS_LIB}", "run.vvp" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS state=3d20bdba\nOBS state=e9dab1d1\nOBS state=9ccc40fc\nfixture.sv:7: $finish called at 3000 (1ps)\n", "runtime_stderr": "", "observed_lines": [ "OBS state=3d20bdba", "OBS state=e9dab1d1", "OBS state=9ccc40fc" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:34:35.905720+00:00", "log": "harness/hdl-simulator-observations/logs/F28-icarus.json" }, "verilator": { "tool_version": "5.052 2026-09-05 rev vUNKNOWN-built20260905", "compile_command": [ "verilator", "--binary", "--timing", "--language", "1800-2012", "--x-assign", "0", "--x-initial", "0", "-Wno-fatal", "--quiet-build", "--quiet-stats", "--quiet-exit", "--top-module", "tb", "--Mdir", "obj", "fixture.sv" ], "execute_command": [ "./obj/Vtb", "+verilator+quiet" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS state=3d20bdba\nOBS state=e9dab1d1\nOBS state=9ccc40fc\n- fixture.sv:7: Verilog $finish\n", "runtime_stderr": "", "observed_lines": [ "OBS state=3d20bdba", "OBS state=e9dab1d1", "OBS state=9ccc40fc" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:34:42.405847+00:00", "log": "harness/hdl-simulator-observations/logs/F28-verilator.json" } }, "observed_payload_equal": true, "interpretation": "Matching OBS payload in these configurations; finish banners and diagnostics are compared separately.", "public_source_path": "/data/hdl-simulator-observations/fixtures/F28.sv" }, { "id": "F29", "title": "Seeded random sequence", "category": "seed", "source": "harness/hdl-simulator-observations/fixtures/F29.sv", "source_sha256": "11fead1264b002b05f40b694ae402d01b82e6573251ff1cef3b7924d546bb38e", "origin": "Original fixture authored for P6.", "observations": { "icarus": { "tool_version": "13.0 stable v13_0", "compile_command": [ "iverilog", "-B", "${ICARUS_LIB}", "-g2012", "-gstrict-expr-width", "-Wall", "-s", "tb", "-o", "run.vvp", "fixture.sv" ], "execute_command": [ "vvp", "-M", "${ICARUS_LIB}", "run.vvp" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS random=8011ec00 seed=0011ea9e\nOBS random=61e0e9c3 seed=e1e0e687\nOBS random=b3547666 seed=3354751c\nfixture.sv:7: $finish called at 3000 (1ps)\n", "runtime_stderr": "", "observed_lines": [ "OBS random=8011ec00 seed=0011ea9e", "OBS random=61e0e9c3 seed=e1e0e687", "OBS random=b3547666 seed=3354751c" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:34:42.215338+00:00", "log": "harness/hdl-simulator-observations/logs/F29-icarus.json" }, "verilator": { "tool_version": "5.052 2026-09-05 rev vUNKNOWN-built20260905", "compile_command": [ "verilator", "--binary", "--timing", "--language", "1800-2012", "--x-assign", "0", "--x-initial", "0", "-Wno-fatal", "--quiet-build", "--quiet-stats", "--quiet-exit", "--top-module", "tb", "--Mdir", "obj", "fixture.sv" ], "execute_command": [ "./obj/Vtb", "+verilator+quiet" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS random=979a27f1 seed=a79f332a\nOBS random=7d04cbad seed=83d6c4a7\nOBS random=9c22637a seed=0e23cf8b\n- fixture.sv:7: Verilog $finish\n", "runtime_stderr": "", "observed_lines": [ "OBS random=979a27f1 seed=a79f332a", "OBS random=7d04cbad seed=83d6c4a7", "OBS random=9c22637a seed=0e23cf8b" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:34:50.365047+00:00", "log": "harness/hdl-simulator-observations/logs/F29-verilator.json" } }, "observed_payload_equal": false, "interpretation": "Built-in seeded random streams differ by implementation; each recorded stream repeats within its own tool.", "public_source_path": "/data/hdl-simulator-observations/fixtures/F29.sv" }, { "id": "F30", "title": "Seeded urandom process", "category": "seed", "source": "harness/hdl-simulator-observations/fixtures/F30.sv", "source_sha256": "6bb48337f0d4c3ce55ae59da60f175a97f690e5f8b320ef755b5bd72b66d03f3", "origin": "Original fixture authored for P6.", "observations": { "icarus": { "tool_version": "13.0 stable v13_0", "compile_command": [ "iverilog", "-B", "${ICARUS_LIB}", "-g2012", "-gstrict-expr-width", "-Wall", "-s", "tb", "-o", "run.vvp", "fixture.sv" ], "execute_command": [ "vvp", "-M", "${ICARUS_LIB}", "run.vvp" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS urandom=0011ec00\nOBS urandom=e1e0e9c3\nOBS urandom=33547666\nfixture.sv:7: $finish called at 3000 (1ps)\n", "runtime_stderr": "", "observed_lines": [ "OBS urandom=0011ec00", "OBS urandom=e1e0e9c3", "OBS urandom=33547666" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:34:42.450798+00:00", "log": "harness/hdl-simulator-observations/logs/F30-icarus.json" }, "verilator": { "tool_version": "5.052 2026-09-05 rev vUNKNOWN-built20260905", "compile_command": [ "verilator", "--binary", "--timing", "--language", "1800-2012", "--x-assign", "0", "--x-initial", "0", "-Wno-fatal", "--quiet-build", "--quiet-stats", "--quiet-exit", "--top-module", "tb", "--Mdir", "obj", "fixture.sv" ], "execute_command": [ "./obj/Vtb", "+verilator+quiet" ], "compile_return_code": 0, "execute_return_code": 0, "compile_stdout": "", "compile_stderr": "", "runtime_stdout": "OBS urandom=a79f332a\nOBS urandom=979a27f1\nOBS urandom=b38d6fdb\n- fixture.sv:7: Verilog $finish\n", "runtime_stderr": "", "observed_lines": [ "OBS urandom=a79f332a", "OBS urandom=979a27f1", "OBS urandom=b38d6fdb" ], "repeat_observed_lines_equal": true, "recorded_at_utc": "2026-10-25T02:34:50.602193+00:00", "log": "harness/hdl-simulator-observations/logs/F30-verilator.json" } }, "observed_payload_equal": false, "interpretation": "Built-in seeded random streams differ by implementation; each recorded stream repeats within its own tool.", "public_source_path": "/data/hdl-simulator-observations/fixtures/F30.sv" } ], "limits": [ "Thirty small examples are not a language-compliance suite or a tool ranking.", "No analog metastability, silicon timing, power intent, physical implementation or performance measurement.", "Verilator zero X policies are selected settings, not every supported mode.", "Only original fixture sources, logs and reproduction code are included; installed tools and generated binaries are excluded." ] }