allwpilib/hal/src/main/native/cpp/Main.cpp

// Copyright (c) FIRST and other WPILib contributors.
// Open Source Software; you can modify and/or share it under the terms of
// the WPILib BSD license file in the root directory of this project.

#include "hal/Main.h"

#include <wpi/condition_variable.h>
#include <wpi/mutex.h>

static void DefaultMain(void*);
static void DefaultExit(void*);

static bool gHasMain = false;
static void* gMainParam = nullptr;
static void (*gMainFunc)(void*) = DefaultMain;
static void (*gExitFunc)(void*) = DefaultExit;
static bool gExited = false;
struct MainObj {
  wpi::mutex gExitMutex;
  wpi::condition_variable gExitCv;
};

static MainObj* mainObj;

static void DefaultMain(void*) {
  std::unique_lock lock{mainObj->gExitMutex};
  mainObj->gExitCv.wait(lock, [] { return gExited; });
}

static void DefaultExit(void*) {
  std::lock_guard lock{mainObj->gExitMutex};
  gExited = true;
  mainObj->gExitCv.notify_all();
}

namespace hal::init {
void InitializeMain() {
  static MainObj mO;
  mainObj = &mO;
}
}  // namespace hal::init

extern "C" {

void HAL_SetMain(void* param, void (*mainFunc)(void*),
                 void (*exitFunc)(void*)) {
  gHasMain = true;
  gMainParam = param;
  gMainFunc = mainFunc;
  gExitFunc = exitFunc;
}

HAL_Bool HAL_HasMain(void) {
  return gHasMain;
}

void HAL_RunMain(void) {
  gMainFunc(gMainParam);
}

void HAL_ExitMain(void) {
  gExitFunc(gMainParam);
}

}  // extern "C"