Method WaitGS

pcsx2/MTGS.cpp:613–659

Waits for the GS to empty out the entire ring buffer contents. If syncRegs, then writes pcsx2's gs regs to MTGS's internal copy If weakWait, then this function is allowed to exit after MTGS finished a path1 packet If isMTVU, then this implies this function is being called from the MTVU thread...

// If weakWait, then this function is allowed to exit after MTGS finished a path1 packet
// If isMTVU, then this implies this function is being called from the MTVU thread...
void MTGS::WaitGS(bool syncRegs, bool weakWait, bool isMTVU)
{
	pxAssertMsg(IsOpen(), "MTGS Warning!  WaitGS issued on a closed thread.");
	if (!IsOpen()) [[unlikely]]
		return;

	Gif_Path& path = gifUnit.gifPath[GIF_PATH_1];

	// Both m_ReadPos and m_WritePos can be relaxed as we only want to test if the queue is empty but
	// we don't want to access the content of the queue

	SetEvent();
	if (weakWait && isMTVU)
	{
		// On weakWait we will stop waiting on the MTGS thread if the
		// MTGS thread has processed a vu1 xgkick packet, or is pending on
		// its final vu1 xgkick packet (!curP1Packs)...
		// Note: m_WritePos doesn't seem to have proper atomic write
		// code, so reading it from the MTVU thread might be dangerous;
		// hence it has been avoided...
		u32 startP1Packs = path.GetPendingGSPackets();
		if (startP1Packs)
		{
			while (true)
			{
				// m_mtx_RingBufferBusy2.Wait();
				s_mtx_RingBufferBusy2.lock();
				s_mtx_RingBufferBusy2.unlock();
				if (path.GetPendingGSPackets() != startP1Packs)
					break;
			}
		}
	}
	else
	{
		if (!s_sem_event.WaitForEmpty())
			pxFailRel("MTGS Thread Died");
	}

	pxAssert(!(weakWait && syncRegs) && "No synchronization for this!");

	if (syncRegs)
	{
		// Completely synchronize GS and MTGS register states.
		memcpy(RingBuffer.Regs, PS2MEM_GS, sizeof(RingBuffer.Regs));
	}
}

// Sets the gsEvent flag and releases a timeslice.
// For use in loops that wait on the GS thread to do certain things.