[hal] Add initial PWM support for systemcore (#7525)

hal/src/main/native/systemcore/SmartIo.h

@@ -0,0 +1,53 @@
+// 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.
+
+#pragma once
+
+#include <string>
+
+#include "PortsInternal.h"
+#include "hal/handles/DigitalHandleResource.h"
+#include "hal/handles/HandlesInternal.h"
+#include "networktables/DoubleTopic.h"
+
+namespace hal {
+
+constexpr int32_t kPwmDisabled = 0;
+constexpr int32_t kPwmAlwaysHigh = 0xFFFF;
+
+enum class SmartIoMode {
+  DigitalInput,
+  PWMOutput,
+};
+
+struct SmartIo {
+  uint8_t channel;
+  bool configSet = false;
+  bool eliminateDeadband = false;
+  int32_t maxPwm = 0;
+  int32_t deadbandMaxPwm = 0;
+  int32_t centerPwm = 0;
+  int32_t deadbandMinPwm = 0;
+  int32_t minPwm = 0;
+  std::string previousAllocation;
+  SmartIoMode currentMode{SmartIoMode::DigitalInput};
+  nt::DoublePublisher modePublisher;
+
+  nt::DoublePublisher setPublisher;
+  nt::DoubleSubscriber getSubscriber;
+
+  nt::DoublePublisher pwmMinPublisher;
+  nt::DoublePublisher pwmMaxPublisher;
+
+  int32_t InitializeMode(SmartIoMode mode);
+  int32_t SetPwmMicroseconds(uint16_t microseconds);
+  int32_t GetPwmMicroseconds(uint16_t* microseconds);
+};
+
+extern DigitalHandleResource<HAL_DigitalHandle, SmartIo, kNumSmartIo>*
+    smartIoHandles;
+
+extern wpi::mutex smartIoMutex;
+
+}  // namespace hal