Use MrcLib to talk to DS by ThadHouse · Pull Request #8858 · wpilibsuite/allwpilib

ThadHouse · 2026-05-06T00:21:18Z

Using MrcLib on the robot is going to be the plan for the future, to make things easier.

MrcLib is how sim is supported going forward. The desktop version of mrclib can act as a robot server.

This is set up where the mrclib interface is in shared code. On robot, that is the only backend used. On desktop, a default sim backend is used. However, the sim plugin can switch that to the real robot backend, so the robot code will exactly look like a real robot.

ThadHouse · 2026-05-06T05:12:12Z

Even if this passed, don't merge this yet. Haven't done the console line stuff, nor have I actually tested it on systemcore.

Copilot

Pull request overview

This PR migrates Driver Station communications toward an MrcLib-backed implementation (robot + sim), while also extending the error/crash reporting surface so failures can be reported to the DS consistently across runtimes.

Changes:

Added a DS “program crash” reporting path and hooked it into RobotBase exception handling.
Refactored HAL DriverStation error/console APIs to use WPI_String and routed DS operations through an MrcLibDs backend (systemcore + sim).
Reworked the halsim_ds_socket extension to use mrclib instead of the legacy DS socket packet parsing implementation, and added mrclib build definitions for Gradle/Bazel.

Reviewed changes

Copilot reviewed 42 out of 42 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
wpilibj/src/main/java/org/wpilib/framework/RobotBase.java	Emits DS crash reports on robot instantiation/runtime exceptions.
wpilibj/src/main/java/org/wpilib/driverstation/internal/DriverStationBackend.java	Adds `reportCrash()` and updates DS error JNI call signature usage.
wpilibj/src/main/java/org/wpilib/driverstation/DriverStationErrors.java	Exposes `reportCrash()` to user code.
wpilibc/src/main/native/include/wpi/framework/RobotBase.hpp	Switches to C++ DriverStation wrapper header and new `SendError()` API.
wpilibc/src/main/native/cpp/system/Notifier.cpp	Updates error sending to new C++ `SendError()` wrapper.
wpilibc/src/main/native/cpp/system/Errors.cpp	Updates error sending to new C++ `SendError()` wrapper.
wpilibc/src/main/native/cpp/simulation/DriverStationSim.cpp	Updates HALSim DS callback signatures to `WPI_String`.
simulation/halsim_ds_socket/src/test/native/cpp/DSCommPacketTest.cpp	Removes tests for legacy DS socket packet parser (parser removed).
simulation/halsim_ds_socket/src/main/native/include/wpi/halsim/ds_socket/DsSocket.h	Adds placeholder header for packaging.
simulation/halsim_ds_socket/src/main/native/include/wpi/halsim/ds_socket/DSCommPacket.hpp	Removes legacy DS packet parser API.
simulation/halsim_ds_socket/src/main/native/include/wpi/halsim/ds_socket/DSCommJoystickPacket.hpp	Removes legacy joystick packet struct.
simulation/halsim_ds_socket/src/main/native/cpp/main.cpp	Reimplements DS socket extension around mrclib + forced DS backend.
simulation/halsim_ds_socket/src/main/native/cpp/DSCommPacket.cpp	Removes legacy DS packet parser implementation.
simulation/CMakeLists.txt	Disables building ds_socket via CMake.
shared/libmrclib.gradle	Adds mrclib as a Gradle native dependency.
shared/bazel/thirdparty/mrclib/mrclib.MODULE.bazel	Adds Bazel http_archives for mrclib artifacts.
shared/bazel/thirdparty/mrclib/BUILD.bazel	Adds Bazel `cc_import` for mrclib shared library.
MODULE.bazel	Includes mrclib module definition.
hal/src/main/python/semiwrap/DriverStation.yml	Exposes new DS-related HAL functions to python semiwrap.
hal/src/main/python/semiwrap/DriverStation_c.yml	Exposes `HAL_SendProgramCrash` to C semiwrap.
hal/src/main/python/hal/src/hal.cpp	Updates to new `DriverStation.hpp` + `WPI_String` print callback signature.
hal/src/main/native/systemcore/HALInitializer.hpp	Removes legacy FIRST DS init symbol.
hal/src/main/native/systemcore/HAL.cpp	Stops calling removed FIRST DS initializer.
hal/src/main/native/systemcore/FIRSTDriverStation.cpp	Removes legacy systemcore DS implementation.
hal/src/main/native/systemcore/DriverStation.cpp	Provides systemcore default DS backend (mrclib).
hal/src/main/native/sim/HALInitializer.hpp	Removes legacy sim DS init symbol.
hal/src/main/native/sim/HAL.cpp	Drops redundant `HAL_GetSystemTimeValid` impl and relies on DS backend.
hal/src/main/native/sim/DriverStation.cpp	Reworks sim DS to an `MrcLibDs` implementation + updated callback signatures.
hal/src/main/native/include/wpi/hal/simulation/MockHooks.h	Updates mock hook callback typedefs to `WPI_String`.
hal/src/main/native/include/wpi/hal/DriverStationTypes.h	Adjusts `HAL_MatchInfo::eventName` sizing.
hal/src/main/native/include/wpi/hal/DriverStation.hpp	Adds C++ wrappers for `SendError/SendConsoleLine/SendProgramCrash`.
hal/src/main/native/include/wpi/hal/DriverStation.h	Changes C API signatures to use `WPI_String` + adds `HAL_SendProgramCrash`.
hal/src/main/native/include/wpi/hal/cpp/MrcLibDs.hpp	Introduces the backend interface for DS implementations.
hal/src/main/native/cpp/mrclib/MrcLibDs.cpp	Adds mrclib-backed DS implementation.
hal/src/main/native/cpp/jni/simulation/DriverStationDataJNI.cpp	Updates lambdas for new HALSim DS callback signatures.
hal/src/main/native/cpp/jni/HALUtil.cpp	Updates HAL error reporting call to new `HAL_SendError` signature.
hal/src/main/native/cpp/jni/DriverStationJNI.cpp	Updates JNI signatures and adds `sendProgramCrash`.
hal/src/main/native/cpp/FIRSTDriverStation.cpp	Adds the HAL entrypoint layer routing calls to the selected DS backend.
hal/src/main/java/org/wpilib/hardware/hal/DriverStationJNI.java	Updates `sendError` signature and adds `sendProgramCrash`.
hal/build.gradle	Wires mrclib into native build dependencies.
hal/BUILD.bazel	Adds mrclib dependency for Bazel builds of hal.
glass/src/lib/native/cpp/other/FMS.cpp	Updates robot mode string from “Test” to “Utility”.

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+#include <algorithm>
+#include <exception>


+// the WPILib BSD license file in the root directory of this project.
+
+#include <atomic>
+#include <cstdio>


+static std::atomic<bool> gDSConnected = true;



+static void WriteSimBackend() {
+  MRC_Joysticks joysticks;
+  MRC_ControlData controlData;

-    client->data.connect([t](Buffer& buf, size_t len) {
-      HandleTcpDataStream(buf, len, *t->GetData<DataStore>());
-    });
-    client->StartRead();
-    client->end.connect([c = client.get()] {
-      c->Close();
-      gDSConnected = false;
-    });
-  });
-}
+  int32_t status =
+      MRC_DsComms_GetControlDataWithJoysticks(&controlData, &joysticks);
+  if (status != 0) {


+  printf("Control data status: 0x%x\n", controlData.controlFlags);
+  fflush(stdout);


+            artifactId = "mrclib-cpp"
+            headerClassifier = "headers"
+            ext = "zip"
+            version = '+'


The initial build file generation for robotpy projects was relatively naive and purpose built to get `allwpilib` compiling, without supporting all the available features. This modifies the generation scripts to be able to support multiple embedded libraries, which will be necessary for #8858, since `mrclib.so` will need to be bundled along with the hal libraries. In addition some cleanup was done to get the wheels looking more like what is in pypi.

This pulls in the `mrclib` maven repository as shared libraries, as a prereq for #8858. Alternative to #8869, which avoids the unnecessary lockfile entry. This should be a one-to-one replacement for that PR. Closes #8869 --------- Co-authored-by: PJ Reiniger <pj.reiniger@gmail.com>

ThadHouse added 4 commits May 5, 2026 12:52

Switch DS to mrclib

cb8f9f8

Fix mrclib backend

e2cdbcc

Merge remote-tracking branch 'wpilibsuite/main' into mrclibds

e6d00df

Simgui works

73d61a5

ThadHouse requested review from a team as code owners May 6, 2026 00:21

ThadHouse added 6 commits May 5, 2026 17:38

Format

5b7fe9c

Fix bazel

70b5d17

Fix cmake

7191d19

Fix things

735590c

Format

2d992fc

1 more lint

d142bd4

Fix cmake compile

7b3a13a

This was referenced May 6, 2026

[python] Improve robotpy generation #8867

Merged

[bazel] Add mrclib dependency #8869

Closed

ThadHouse added 10 commits May 7, 2026 17:04

Fix printing

bf123a5

Program crash support

3fe414c

An attempt at gradle

410ec40

Attempt to fix the toy build system

c8b57fb

Fix lint

6ef62cf

Mor ebazel

190c9fc

Format

7730207

Pregen

b55fd88

Merge branch 'main' into mrclibds

344ec24

Format

745aaf7

auscompgeek mentioned this pull request May 8, 2026

[bazel] Add mrclib dependency #8873

Merged

ThadHouse added 2 commits May 7, 2026 18:40

Another bazel fix

2fe0bb0

Fix C++ test

95f2083

ThadHouse added 6 commits May 7, 2026 18:57

Fix some things

51af4b5

Merge main

f004425

Fix bazel

678a52e

Fix header location

8a737b7

Fully revert bazel

d060078

Update bazel and hashes

cc4e62c

ThadHouse requested a review from Copilot May 13, 2026 19:35

Copilot started reviewing on behalf of ThadHouse May 13, 2026 19:36 View session

Copilot AI reviewed May 13, 2026

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Use MrcLib to talk to DS#8858

Use MrcLib to talk to DS#8858
ThadHouse wants to merge 29 commits into
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ThadHouse:mrclibds

ThadHouse commented May 6, 2026

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		printf("Control data status: 0x%x\n", controlData.controlFlags);
		fflush(stdout);

		#include <algorithm>
		#include <exception>

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ThadHouse commented May 6, 2026

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Pull request overview

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