Workaround ACL overflow issues by not dropping packets until buffer reaches size of 100.

It seems to work without causing input delays or anything bad.

Source/Core/Core/Src/IPC_HLE/WII_IPC_HLE_Device_usb.cpp

@@ -336,23 +336,23 @@ void CWII_IPC_HLE_Device_usb_oh1_57e_305::SendToDevice(u16 _ConnectionHandle, u8
 	pWiiMote->ExecuteL2capCmd(_pData, _Size);
 }
 
-// Here we send ACL packets to CPU. They will consist of header + data.
-// The header is for example 07 00 41 00 which means size 0x0007 and channel 0x0041.
-// ---------------------------------------------------
-// AyuanX: Basically, our WII_IPC_HLE is efficient enough to send the packet immediately
-// rather than enqueue it to some other memory 
-// But...the only exception comes from the Wiimote_Plugin
 void CWII_IPC_HLE_Device_usb_oh1_57e_305::IncDataPacket(u16 _ConnectionHandle)
 {
 	m_PacketCount[_ConnectionHandle & 0xff]++;
 
+	// I don't think this makes sense or should be necessary
+	// m_PacketCount refers to "completed" packets and is not related to some buffer size, yes?
+#if 0
 	if (m_PacketCount[_ConnectionHandle & 0xff] > (unsigned int)m_acl_pkts_num)
 	{
 		DEBUG_LOG(WII_IPC_WIIMOTE, "ACL buffer overflow");
 		m_PacketCount[_ConnectionHandle & 0xff] = m_acl_pkts_num;
 	}
+#endif
 }
 
+// Here we send ACL packets to CPU. They will consist of header + data.
+// The header is for example 07 00 41 00 which means size 0x0007 and channel 0x0041.
 void CWII_IPC_HLE_Device_usb_oh1_57e_305::SendACLPacket(u16 _ConnectionHandle, u8* _pData, u32 _Size)
 {
 	DEBUG_LOG(WII_IPC_WIIMOTE, "ACL packet from %x ready to send to stack...", _ConnectionHandle);
@@ -374,8 +374,7 @@ void CWII_IPC_HLE_Device_usb_oh1_57e_305::SendACLPacket(u16 _ConnectionHandle, u
 	}
 	else
 	{
-		DEBUG_LOG(WII_IPC_WIIMOTE, "ACL endpoint not currently valid, "
+		DEBUG_LOG(WII_IPC_WIIMOTE, "ACL endpoint not currently valid, queueing...");
-			"queueing(%d)...", m_acl_pool.GetWritePos());
 		m_acl_pool.Store(_pData, _Size, _ConnectionHandle);
 	}
 }
@@ -518,25 +517,51 @@ u32 CWII_IPC_HLE_Device_usb_oh1_57e_305::Update()
 	return packet_transferred;
 }
 
+void CWII_IPC_HLE_Device_usb_oh1_57e_305::ACLPool::Store(const u8* data, const u16 size, const u16 conn_handle)
+{
+	if (m_queue.size() >= 100)
+	{
+		// Many simultaneous exchanges of ACL packets tend to cause the
+		// queue to fill up. Typically, this occurs when
+		// many emulated Wiimotes are requesting connections at once.
+		// See issue 4608 for more info.
+		ERROR_LOG(WII_IPC_WIIMOTE, "ACL queue size reached 100 - current packet will be "
+				"dropped! (Hopefully you never see this.)");
+		return;
+	}
+	
+	_dbg_assert_msg_(WII_IPC_WIIMOTE,
+		size < m_acl_pkt_size, "acl packet too large for pool");
+	
+	m_queue.push_back(Packet());
+	auto& packet = m_queue.back();
+	
+	std::copy_n(data, size, packet.data);
+	packet.size = size;
+	packet.conn_handle = conn_handle;
+}
+
 void CWII_IPC_HLE_Device_usb_oh1_57e_305::ACLPool::WriteToEndpoint(CtrlBuffer& endpoint)
 {
-	const u8 *data = m_pool + m_acl_pkt_size * m_read_ptr;
+	auto& packet = m_queue.front();
-	const u16 size = m_info[m_read_ptr].size;
+	
-	const u16 conn_handle = m_info[m_read_ptr].conn_handle;
+	const u8* const data = packet.data;
+	const u16 size = packet.size;
+	const u16 conn_handle = packet.conn_handle;
 
 	DEBUG_LOG(WII_IPC_WIIMOTE, "ACL packet being written from "
-		"queue(%d) to %08x", GetReadPos(),	endpoint.m_address);
+		"queue to %08x", endpoint.m_address);
 
 	hci_acldata_hdr_t* pHeader = (hci_acldata_hdr_t*)Memory::GetPointer(endpoint.m_buffer);
 	pHeader->con_handle	= HCI_MK_CON_HANDLE(conn_handle, HCI_PACKET_START, HCI_POINT2POINT);
 	pHeader->length		= size;
 
 	// Write the packet to the buffer
-	memcpy((u8*)pHeader + sizeof(hci_acldata_hdr_t), data, pHeader->length);
+	std::copy_n(data, pHeader->length, (u8*)pHeader + sizeof(hci_acldata_hdr_t));
 
 	endpoint.SetRetVal(sizeof(hci_acldata_hdr_t) + size);
 
-	m_read_ptr = (m_read_ptr + 1) % m_acl_pkts_num;
+	m_queue.pop_front();
 
 	WII_IPC_HLE_Interface::EnqReply(endpoint.m_address);
 	endpoint.Invalidate();

Source/Core/Core/Src/IPC_HLE/WII_IPC_HLE_Device_usb.h

@@ -17,9 +17,11 @@
 
 #pragma once
 
-#include "hci.h"
+#include <algorithm>
 #include <vector>
 #include <queue>
+
+#include "hci.h"
 #include "WII_IPC_HLE.h"
 #include "WII_IPC_HLE_Device.h"
 #include "WII_IPC_HLE_WiiMote.h"
@@ -168,70 +170,33 @@ private:
 
 	class ACLPool
 	{
-		u8 m_pool[m_acl_pkt_size * m_acl_pkts_num];
+		struct Packet
-		int m_read_ptr;
-		int m_write_ptr;
-
-		struct
 		{
+			u8 data[m_acl_pkt_size];
 			u16 size;
 			u16 conn_handle;
-		} m_info[m_acl_pkts_num];
+		};
+		
+		std::deque<Packet> m_queue;
 
 	public:
 		ACLPool()
-			: m_read_ptr(0)
+			: m_queue()
-			, m_write_ptr(0)
 		{}
 
-		void Store(const u8* data, const u16 size, const u16 conn_handle)
+		void Store(const u8* data, const u16 size, const u16 conn_handle);
-		{
-			_dbg_assert_msg_(WII_IPC_WIIMOTE,
-				size < m_acl_pkt_size, "acl packet too large for pool");
-
-			const int next_write_ptr = (m_write_ptr + 1) % m_acl_pkts_num;
-			if (next_write_ptr == m_read_ptr)
-			{
-				// Many simultaneous exchanges of ACL packets tend to cause the
-				// 10-packet limit to be exceeded.  Typically, this occurs when
-				// many emulated Wiimotes are requesting connections at once.
-				// See issue 4608 for more info.
-				ERROR_LOG(WII_IPC_WIIMOTE, "ACL queue is full - current packet will be "
-						"dropped! (m_write_ptr(%d) was about to overlap m_read_ptr(%d))",
-						m_write_ptr, m_read_ptr);
-				return;
-			}
-
-			memcpy(m_pool + m_acl_pkt_size * m_write_ptr, data, size);
-			m_info[m_write_ptr].size = size;
-			m_info[m_write_ptr].conn_handle = conn_handle;
-			m_write_ptr = next_write_ptr;
-		}
 
 		void WriteToEndpoint(CtrlBuffer& endpoint);
 
 		bool IsEmpty() const
 		{
-			return m_write_ptr == m_read_ptr;
+			return m_queue.empty();
-		}
-
-		int GetWritePos() const
-		{
-			return m_write_ptr;
-		}
-
-		int GetReadPos() const
-		{
-			return m_read_ptr;
 		}
 
 		// For SaveStates
 		void DoState(PointerWrap &p)
 		{
-			p.Do(m_write_ptr);
+			p.Do(m_queue);
-			p.Do(m_read_ptr);
-			p.DoArray((u8 *)m_pool, sizeof(m_pool));
-			p.DoArray((u8 *)m_info, sizeof(m_info));
 		}
 	} m_acl_pool;