Add Low Fidelity NetworkTables simulation extension (#823)

simulation/halsim_lowfi/src/main/native/cpp/HALSimLowFi.cpp

@@ -0,0 +1,62 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2017 FIRST. All Rights Reserved.                             */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "HALSimLowFi.h"
+
+#include <llvm/Twine.h>
+
+void HALSimLowFi::Initialize() {
+  table = nt::NetworkTableInstance::GetDefault().GetTable("sim");
+}
+
+void HALSimNTProvider::Inject(std::shared_ptr<HALSimLowFi> parentArg,
+                              std::string tableNameArg) {
+  parent = parentArg;
+  tableName = std::move(tableNameArg);
+  table = parent->table->GetSubTable(tableName);
+
+  this->Initialize();
+}
+
+void NTProviderBaseCallback(const char* name, void* param,
+                            const struct HAL_Value* value) {
+  auto info =
+      static_cast<struct HALSimNTProvider::NTProviderCallbackInfo*>(param);
+  uint32_t chan = static_cast<uint32_t>(info->channel);
+  auto provider = info->provider;
+  auto table = info->table;
+  provider->OnCallback(chan, table);
+}
+
+void HALSimNTProvider::InitializeDefault(
+    int numChannels, HALCbRegisterIndexedFunc registerFunc) {
+  this->numChannels = numChannels;
+  cbInfos.reserve(numChannels);
+  for (int i = 0; i < numChannels; i++) {
+    struct NTProviderCallbackInfo info = {
+        this, table->GetSubTable(tableName + llvm::Twine(i)), i};
+    cbInfos.emplace_back(info);
+  }
+
+  for (auto& info : cbInfos) {
+    registerFunc(info.channel, NTProviderBaseCallback, &info, true);
+    OnInitializedChannel(info.channel, info.table);
+  }
+}
+
+void HALSimNTProvider::InitializeDefaultSingle(
+    HALCbRegisterSingleFunc registerFunc) {
+  struct NTProviderCallbackInfo info = {this, table, 0};
+  cbInfos.push_back(info);
+
+  for (auto& info : cbInfos) {
+    registerFunc(NTProviderBaseCallback, &info, true);
+  }
+}
+
+void HALSimNTProvider::OnInitializedChannel(
+    uint32_t channel, std::shared_ptr<nt::NetworkTable> table) {}