SVC: Implemented GetThreadId.

For now threads are using their Handle value as their Id, it should not really cause any problems because Handle values are unique in Citra, but it should be changed. I left a ToDo there because this is not correct behavior as per hardware.

src/core/hle/kernel/thread.cpp

@@ -49,6 +49,8 @@ public:
 
     ThreadContext context;
 
+    u32 thread_id;
+
     u32 status;
     u32 entry_point;
     u32 stack_top;
@@ -325,6 +327,9 @@ Thread* CreateThread(Handle& handle, const char* name, u32 entry_point, s32 prio
     thread_queue.push_back(handle);
     thread_ready_queue.prepare(priority);
 
+    // TODO(Subv): Assign valid ids to each thread, they are much lower than handle values
+    // they appear to begin at 276 and continue from there
+    thread->thread_id = handle; 
     thread->status = THREADSTATUS_DORMANT;
     thread->entry_point = entry_point;
     thread->stack_top = stack_top;
@@ -465,6 +470,17 @@ void Reschedule() {
     }
 }
 
+ResultCode GetThreadId(u32* thread_id, Handle handle) {
+    Thread* thread = g_object_pool.Get<Thread>(handle);
+    if (thread == nullptr)
+        return ResultCode(ErrorDescription::InvalidHandle, ErrorModule::OS, 
+                          ErrorSummary::WrongArgument, ErrorLevel::Permanent);
+
+    *thread_id = thread->thread_id;
+
+    return RESULT_SUCCESS;
+}
+
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
 void ThreadingInit() {

src/core/hle/kernel/thread.h

@@ -58,6 +58,9 @@ void Reschedule();
 /// Stops the current thread
 ResultCode StopThread(Handle thread, const char* reason);
 
+// Retrieves the thread id of the specified thread handle
+ResultCode GetThreadId(u32* thread_id, Handle handle);
+
 /// Resumes a thread from waiting by marking it as "ready"
 void ResumeThreadFromWait(Handle handle);
 

src/core/hle/svc.cpp

@@ -281,10 +281,11 @@ static Result ReleaseMutex(Handle handle) {
     return res.raw;
 }
 
-/// Get current thread ID
+/// Get the ID for the specified thread.
-static Result GetThreadId(u32* thread_id, Handle thread) {
+static Result GetThreadId(u32* thread_id, Handle handle) {
-    ERROR_LOG(SVC, "(UNIMPLEMENTED) called thread=0x%08X", thread);
+    DEBUG_LOG(SVC, "called thread=0x%08X", handle);
-    return 0;
+    ResultCode result = Kernel::GetThreadId(thread_id, handle);
+    return result.raw;
 }
 
 /// Query memory