[XAM/INFO] - Implement XamGetDashBackstackData

- Implement XamGetDashBackstackData

src/xenia/kernel/xam/xam.h

@@ -199,6 +199,11 @@ struct X_DASH_APP_INFO {
 };
 static_assert_size(X_DASH_APP_INFO, 0xC);
 
+struct X_DASH_BACKSTACK_DATA {
+  uint8_t unk1[0x314];
+};
+static_assert_size(X_DASH_BACKSTACK_DATA, 0x314);
+
 struct X_GUID {
   xe::be<uint32_t> Data1;
   xe::be<uint16_t> Data2;

src/xenia/kernel/xam/xam_info.cc

@@ -788,6 +788,22 @@ void XamGetActiveDashAppInfo_entry(pointer_t<X_DASH_APP_INFO> dash_app) {
 }
 DECLARE_XAM_EXPORT1(XamGetActiveDashAppInfo, kNone, kImplemented);
 
+dword_result_t XamGetDashBackstackData_entry(
+    pointer_t<X_DASH_BACKSTACK_DATA> backstack_data, lpdword_t count) {
+  auto xam_state_ = kernel_state()->xam_state();
+  uint32_t total = xam_state_->dash_backstack_nodes_count_;
+  if (total) {
+    if (*count <= total) {
+      total = *count;
+    }
+    std::memcpy(backstack_data, &xam_state_->dash_backstack_data_,
+                sizeof(X_DASH_BACKSTACK_DATA) * total);
+    xam_state_->dash_backstack_nodes_count_ = 0;
+  }
+  return X_ERROR_SUCCESS;
+}
+DECLARE_XAM_EXPORT1(XamGetDashBackstackData, kNone, kImplemented);
+
 void XampWebInstrumentationSetProfileCounts_entry(dword_t live_profiles,
                                                   dword_t local_profiles,
                                                   dword_t adult_profiles,

src/xenia/kernel/xam/xam_state.h

@@ -58,6 +58,8 @@ class XamState {
   void LoadSpaInfo(const SpaInfo* info);
 
   X_DASH_APP_INFO dash_app_info_ = {};
+  uint32_t dash_backstack_nodes_count_ = 0;
+  X_DASH_BACKSTACK_DATA dash_backstack_data_[2] = {};
 
   std::atomic<int32_t> xam_dialogs_shown_ = {0};
   std::atomic<int32_t> xam_nui_dialogs_shown_ = {0};