am: Stub GetPreviousProgramIndex

- Used in Super Mario 3D All-Stars

src/core/hle/service/am/am.cpp

@@ -1192,7 +1192,7 @@ IApplicationFunctions::IApplicationFunctions(Core::System& system_)
         {120, nullptr, "ExecuteProgram"},
         {121, nullptr, "ClearUserChannel"},
         {122, nullptr, "UnpopToUserChannel"},
-        {123, nullptr, "GetPreviousProgramIndex"},
+        {123, &IApplicationFunctions::GetPreviousProgramIndex, "GetPreviousProgramIndex"},
         {124, nullptr, "EnableApplicationAllThreadDumpOnCrash"},
         {130, &IApplicationFunctions::GetGpuErrorDetectedSystemEvent, "GetGpuErrorDetectedSystemEvent"},
         {140, &IApplicationFunctions::GetFriendInvitationStorageChannelEvent, "GetFriendInvitationStorageChannelEvent"},
@@ -1554,6 +1554,14 @@ void IApplicationFunctions::QueryApplicationPlayStatisticsByUid(Kernel::HLEReque
     rb.Push<u32>(0);
 }
 
+void IApplicationFunctions::GetPreviousProgramIndex(Kernel::HLERequestContext& ctx) {
+    LOG_WARNING(Service_AM, "(STUBBED) called");
+
+    IPC::ResponseBuilder rb{ctx, 3};
+    rb.Push(RESULT_SUCCESS);
+    rb.Push<s32>(previous_program_index);
+}
+
 void IApplicationFunctions::GetGpuErrorDetectedSystemEvent(Kernel::HLERequestContext& ctx) {
     LOG_WARNING(Service_AM, "(STUBBED) called");
 

src/core/hle/service/am/am.h

@@ -288,11 +288,13 @@ private:
     void SetApplicationCopyrightVisibility(Kernel::HLERequestContext& ctx);
     void QueryApplicationPlayStatistics(Kernel::HLERequestContext& ctx);
     void QueryApplicationPlayStatisticsByUid(Kernel::HLERequestContext& ctx);
+    void GetPreviousProgramIndex(Kernel::HLERequestContext& ctx);
     void GetGpuErrorDetectedSystemEvent(Kernel::HLERequestContext& ctx);
     void GetFriendInvitationStorageChannelEvent(Kernel::HLERequestContext& ctx);
 
     bool launch_popped_application_specific = false;
     bool launch_popped_account_preselect = false;
+    s32 previous_program_index{-1};
     Kernel::EventPair gpu_error_detected_event;
     Kernel::EventPair friend_invitation_storage_channel_event;
     Core::System& system;