1 files changed, 634 insertions, 0 deletions
diff --git a/src/frontend/qt_sdl/LocalMP.cpp b/src/frontend/qt_sdl/LocalMP.cpp
new file mode 100644
index 0000000..fb7ef7a
--- /dev/null
+++ b/src/frontend/qt_sdl/LocalMP.cpp
@@ -0,0 +1,634 @@
+/*
+    Copyright 2016-2022 melonDS team
+
+    This file is part of melonDS.
+
+    melonDS is free software: you can redistribute it and/or modify it under
+    the terms of the GNU General Public License as published by the Free
+    Software Foundation, either version 3 of the License, or (at your option)
+    any later version.
+
+    melonDS is distributed in the hope that it will be useful, but WITHOUT ANY
+    WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+    FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License along
+    with melonDS. If not, see http://www.gnu.org/licenses/.
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#ifdef __WIN32__
+    #include <windows.h>
+#else
+    #include <fcntl.h>
+    #include <semaphore.h>
+    #include <time.h>
+    #ifdef __APPLE__
+        #include "sem_timedwait.h"
+    #endif
+#endif
+
+#include <string>
+#include <QSharedMemory>
+
+#include "Config.h"
+#include "LocalMP.h"
+
+
+namespace LocalMP
+{
+
+u32 MPUniqueID;
+u8 PacketBuffer[2048];
+
+struct MPQueueHeader
+{
+    u16 NumInstances;
+    u16 InstanceBitmask;  // bitmask of all instances present
+    u16 ConnectedBitmask; // bitmask of which instances are ready to send/receive packets
+    u32 PacketWriteOffset;
+    u32 ReplyWriteOffset;
+    u16 MPHostInstanceID; // instance ID from which the last CMD frame was sent
+    u16 MPReplyBitmask;   // bitmask of which clients replied in time
+};
+
+struct MPPacketHeader
+{
+    u32 Magic;
+    u32 SenderID;
+    u32 Type;       // 0=regular 1=CMD 2=reply 3=ack
+    u32 Length;
+    u64 Timestamp;
+};
+
+struct MPSync
+{
+    u32 Magic;
+    u32 SenderID;
+    u16 ClientMask;
+    u16 Type;
+    u64 Timestamp;
+};
+
+QSharedMemory* MPQueue;
+int InstanceID;
+u32 PacketReadOffset;
+u32 ReplyReadOffset;
+
+const u32 kQueueSize = 0x20000;
+const u32 kMaxFrameSize = 0x800;
+const u32 kPacketStart = sizeof(MPQueueHeader);
+const u32 kReplyStart = kQueueSize / 2;
+const u32 kPacketEnd = kReplyStart;
+const u32 kReplyEnd = kQueueSize;
+
+int RecvTimeout;
+
+int LastHostID;
+
+
+// we need to come up with our own abstraction layer for named semaphores
+// because QSystemSemaphore doesn't support waiting with a timeout
+// and, as such, is unsuitable to our needs
+
+#ifdef __WIN32__
+
+bool SemInited[32];
+HANDLE SemPool[32];
+
+void SemPoolInit()
+{
+    for (int i = 0; i < 32; i++)
+    {
+        SemPool[i] = INVALID_HANDLE_VALUE;
+        SemInited[i] = false;
+    }
+}
+
+void SemDeinit(int num);
+
+void SemPoolDeinit()
+{
+    for (int i = 0; i < 32; i++)
+        SemDeinit(i);
+}
+
+bool SemInit(int num)
+{
+    if (SemInited[num])
+        return true;
+
+    char semname[64];
+    sprintf(semname, "Local\\melonNIFI_Sem%02d", num);
+
+    HANDLE sem = CreateSemaphore(nullptr, 0, 64, semname);
+    SemPool[num] = sem;
+    SemInited[num] = true;
+    return sem != INVALID_HANDLE_VALUE;
+}
+
+void SemDeinit(int num)
+{
+    if (SemPool[num] != INVALID_HANDLE_VALUE)
+    {
+        CloseHandle(SemPool[num]);
+        SemPool[num] = INVALID_HANDLE_VALUE;
+    }
+
+    SemInited[num] = false;
+}
+
+bool SemPost(int num)
+{
+    SemInit(num);
+    return ReleaseSemaphore(SemPool[num], 1, nullptr) != 0;
+}
+
+bool SemWait(int num, int timeout)
+{
+    return WaitForSingleObject(SemPool[num], timeout) == WAIT_OBJECT_0;
+}
+
+void SemReset(int num)
+{
+    while (WaitForSingleObject(SemPool[num], 0) == WAIT_OBJECT_0);
+}
+
+#else
+
+bool SemInited[32];
+sem_t* SemPool[32];
+
+void SemPoolInit()
+{
+    for (int i = 0; i < 32; i++)
+    {
+        SemPool[i] = SEM_FAILED;
+        SemInited[i] = false;
+    }
+}
+
+void SemDeinit(int num);
+
+void SemPoolDeinit()
+{
+    for (int i = 0; i < 32; i++)
+        SemDeinit(i);
+}
+
+bool SemInit(int num)
+{
+    if (SemInited[num])
+        return true;
+
+    char semname[64];
+    sprintf(semname, "/melonNIFI_Sem%02d", num);
+
+    sem_t* sem = sem_open(semname, O_CREAT, 0644, 0);
+    SemPool[num] = sem;
+    SemInited[num] = true;
+    return sem != SEM_FAILED;
+}
+
+void SemDeinit(int num)
+{
+    if (SemPool[num] != SEM_FAILED)
+    {
+        sem_close(SemPool[num]);
+        SemPool[num] = SEM_FAILED;
+    }
+
+    SemInited[num] = false;
+}
+
+bool SemPost(int num)
+{
+    SemInit(num);
+    return sem_post(SemPool[num]) == 0;
+}
+
+bool SemWait(int num, int timeout)
+{
+    if (!timeout)
+        return sem_trywait(SemPool[num]) == 0;
+
+    struct timespec ts;
+    clock_gettime(CLOCK_REALTIME, &ts);
+    ts.tv_nsec += timeout * 1000000;
+    long sec = ts.tv_nsec / 1000000000;
+    ts.tv_nsec -= sec * 1000000000;
+    ts.tv_sec += sec;
+
+    return sem_timedwait(SemPool[num], &ts) == 0;
+}
+
+void SemReset(int num)
+{
+    while (sem_trywait(SemPool[num]) == 0);
+}
+
+#endif
+
+
+bool Init()
+{
+    MPQueue = new QSharedMemory("melonNIFI");
+
+    if (!MPQueue->attach())
+    {
+        printf("MP sharedmem doesn't exist. creating\n");
+        if (!MPQueue->create(kQueueSize))
+        {
+            printf("MP sharedmem create failed :(\n");
+            return false;
+        }
+
+        MPQueue->lock();
+        memset(MPQueue->data(), 0, MPQueue->size());
+        MPQueueHeader* header = (MPQueueHeader*)MPQueue->data();
+        header->PacketWriteOffset = kPacketStart;
+        header->ReplyWriteOffset = kReplyStart;
+        MPQueue->unlock();
+    }
+
+    MPQueue->lock();
+    MPQueueHeader* header = (MPQueueHeader*)MPQueue->data();
+
+    u16 mask = header->InstanceBitmask;
+    for (int i = 0; i < 16; i++)
+    {
+        if (!(mask & (1<<i)))
+        {
+            InstanceID = i;
+            header->InstanceBitmask |= (1<<i);
+            //header->ConnectedBitmask |= (1 << i);
+            break;
+        }
+    }
+    header->NumInstances++;
+
+    PacketReadOffset = header->PacketWriteOffset;
+    ReplyReadOffset = header->ReplyWriteOffset;
+
+    MPQueue->unlock();
+
+    // prepare semaphores
+    // semaphores 0-15: regular frames; semaphore I is posted when instance I needs to process a new frame
+    // semaphores 16-31: MP replies; semaphore I is posted when instance I needs to process a new MP reply
+
+    SemPoolInit();
+    SemInit(InstanceID);
+    SemInit(16+InstanceID);
+
+    LastHostID = -1;
+
+    printf("MP comm init OK, instance ID %d\n", InstanceID);
+
+    RecvTimeout = 25;
+
+    return true;
+}
+
+void DeInit()
+{
+    MPQueue->lock();
+    MPQueueHeader* header = (MPQueueHeader*)MPQueue->data();
+    header->ConnectedBitmask &= ~(1 << InstanceID);
+    header->InstanceBitmask &= ~(1 << InstanceID);
+    header->NumInstances--;
+    MPQueue->unlock();
+
+    SemPoolDeinit();
+
+    MPQueue->detach();
+    delete MPQueue;
+}
+
+void SetRecvTimeout(int timeout)
+{
+    RecvTimeout = timeout;
+}
+
+void Begin()
+{
+    MPQueue->lock();
+    MPQueueHeader* header = (MPQueueHeader*)MPQueue->data();
+    PacketReadOffset = header->PacketWriteOffset;
+    ReplyReadOffset = header->ReplyWriteOffset;
+    SemReset(InstanceID);
+    SemReset(16+InstanceID);
+    header->ConnectedBitmask |= (1 << InstanceID);
+    MPQueue->unlock();
+}
+
+void End()
+{
+    MPQueue->lock();
+    MPQueueHeader* header = (MPQueueHeader*)MPQueue->data();
+    //SemReset(InstanceID);
+    //SemReset(16+InstanceID);
+    header->ConnectedBitmask &= ~(1 << InstanceID);
+    MPQueue->unlock();
+}
+
+void FIFORead(int fifo, void* buf, int len)
+{
+    u8* data = (u8*)MPQueue->data();
+
+    u32 offset, start, end;
+    if (fifo == 0)
+    {
+        offset = PacketReadOffset;
+        start = kPacketStart;
+        end = kPacketEnd;
+    }
+    else
+    {
+        offset = ReplyReadOffset;
+        start = kReplyStart;
+        end = kReplyEnd;
+    }
+
+    if ((offset + len) >= end)
+    {
+        u32 part1 = end - offset;
+        memcpy(buf, &data[offset], part1);
+        memcpy(&((u8*)buf)[part1], &data[start], len - part1);
+        offset = start + len - part1;
+    }
+    else
+    {
+        memcpy(buf, &data[offset], len);
+        offset += len;
+    }
+
+    if (fifo == 0) PacketReadOffset = offset;
+    else           ReplyReadOffset = offset;
+}
+
+void FIFOWrite(int fifo, void* buf, int len)
+{
+    u8* data = (u8*)MPQueue->data();
+    MPQueueHeader* header = (MPQueueHeader*)&data[0];
+
+    u32 offset, start, end;
+    if (fifo == 0)
+    {
+        offset = header->PacketWriteOffset;
+        start = kPacketStart;
+        end = kPacketEnd;
+    }
+    else
+    {
+        offset = header->ReplyWriteOffset;
+        start = kReplyStart;
+        end = kReplyEnd;
+    }
+
+    if ((offset + len) >= end)
+    {
+        u32 part1 = end - offset;
+        memcpy(&data[offset], buf, part1);
+        memcpy(&data[start], &((u8*)buf)[part1], len - part1);
+        offset = start + len - part1;
+    }
+    else
+    {
+        memcpy(&data[offset], buf, len);
+        offset += len;
+    }
+
+    if (fifo == 0) header->PacketWriteOffset = offset;
+    else           header->ReplyWriteOffset = offset;
+}
+
+int SendPacketGeneric(u32 type, u8* packet, int len, u64 timestamp)
+{
+    MPQueue->lock();
+    u8* data = (u8*)MPQueue->data();
+    MPQueueHeader* header = (MPQueueHeader*)&data[0];
+
+    u16 mask = header->ConnectedBitmask;
+
+    // TODO: check if the FIFO is full!
+
+    MPPacketHeader pktheader;
+    pktheader.Magic = 0x4946494E;
+    pktheader.SenderID = InstanceID;
+    pktheader.Type = type;
+    pktheader.Length = len;
+    pktheader.Timestamp = timestamp;
+
+    type &= 0xFFFF;
+    int nfifo = (type == 2) ? 1 : 0;
+    FIFOWrite(nfifo, &pktheader, sizeof(pktheader));
+    if (len)
+        FIFOWrite(nfifo, packet, len);
+
+    if (type == 1)
+    {
+        // NOTE: this is not guarded against, say, multiple multiplay games happening on the same machine
+        // we would need to pass the packet's SenderID through the wifi module for that
+        header->MPHostInstanceID = InstanceID;
+        header->MPReplyBitmask = 0;
+        ReplyReadOffset = header->ReplyWriteOffset;
+        SemReset(16 + InstanceID);
+    }
+    else if (type == 2)
+    {
+        header->MPReplyBitmask |= (1 << InstanceID);
+    }
+
+    MPQueue->unlock();
+
+    if (type == 2)
+    {
+        SemPost(16 + header->MPHostInstanceID);
+    }
+    else
+    {
+        for (int i = 0; i < 16; i++)
+        {
+            if (mask & (1<<i))
+                SemPost(i);
+        }
+    }
+
+    return len;
+}
+
+int RecvPacketGeneric(u8* packet, bool block, u64* timestamp)
+{
+    for (;;)
+    {
+        if (!SemWait(InstanceID, block ? RecvTimeout : 0))
+        {
+            return 0;
+        }
+
+        MPQueue->lock();
+        u8* data = (u8*)MPQueue->data();
+        MPQueueHeader* header = (MPQueueHeader*)&data[0];
+
+        MPPacketHeader pktheader;
+        FIFORead(0, &pktheader, sizeof(pktheader));
+
+        if (pktheader.Magic != 0x4946494E)
+        {
+            printf("PACKET FIFO OVERFLOW\n");
+            PacketReadOffset = header->PacketWriteOffset;
+            SemReset(InstanceID);
+            MPQueue->unlock();
+            return 0;
+        }
+
+        if (pktheader.SenderID == InstanceID)
+        {
+            // skip this packet
+            PacketReadOffset += pktheader.Length;
+            if (PacketReadOffset >= kPacketEnd)
+                PacketReadOffset += kPacketStart - kPacketEnd;
+
+            MPQueue->unlock();
+            continue;
+        }
+
+        if (pktheader.Length)
+        {
+            FIFORead(0, packet, pktheader.Length);
+
+            if (pktheader.Type == 1)
+                LastHostID = pktheader.SenderID;
+        }
+
+        if (timestamp) *timestamp = pktheader.Timestamp;
+        MPQueue->unlock();
+        return pktheader.Length;
+    }
+}
+
+int SendPacket(u8* packet, int len, u64 timestamp)
+{
+    return SendPacketGeneric(0, packet, len, timestamp);
+}
+
+int RecvPacket(u8* packet, u64* timestamp)
+{
+    return RecvPacketGeneric(packet, false, timestamp);
+}
+
+
+int SendCmd(u8* packet, int len, u64 timestamp)
+{
+    return SendPacketGeneric(1, packet, len, timestamp);
+}
+
+int SendReply(u8* packet, int len, u64 timestamp, u16 aid)
+{
+    return SendPacketGeneric(2 | (aid<<16), packet, len, timestamp);
+}
+
+int SendAck(u8* packet, int len, u64 timestamp)
+{
+    return SendPacketGeneric(3, packet, len, timestamp);
+}
+
+int RecvHostPacket(u8* packet, u64* timestamp)
+{
+    if (LastHostID != -1)
+    {
+        // check if the host is still connected
+
+        MPQueue->lock();
+        u8* data = (u8*)MPQueue->data();
+        MPQueueHeader* header = (MPQueueHeader*)&data[0];
+        u16 curinstmask = header->ConnectedBitmask;
+        MPQueue->unlock();
+
+        if (!(curinstmask & (1 << LastHostID)))
+            return -1;
+    }
+
+    return RecvPacketGeneric(packet, true, timestamp);
+}
+
+u16 RecvReplies(u8* packets, u64 timestamp, u16 aidmask)
+{
+    u16 ret = 0;
+    u16 myinstmask = (1 << InstanceID);
+    u16 curinstmask;
+
+    {
+        MPQueue->lock();
+        u8* data = (u8*)MPQueue->data();
+        MPQueueHeader* header = (MPQueueHeader*)&data[0];
+        curinstmask = header->ConnectedBitmask;
+        MPQueue->unlock();
+    }
+
+    // if all clients have left: return early
+    if ((myinstmask & curinstmask) == curinstmask)
+        return 0;
+
+    for (;;)
+    {
+        if (!SemWait(16+InstanceID, RecvTimeout))
+        {
+            // no more replies available
+            return ret;
+        }
+
+        MPQueue->lock();
+        u8* data = (u8*)MPQueue->data();
+        MPQueueHeader* header = (MPQueueHeader*)&data[0];
+
+        MPPacketHeader pktheader;
+        FIFORead(1, &pktheader, sizeof(pktheader));
+
+        if (pktheader.Magic != 0x4946494E)
+        {
+            printf("REPLY FIFO OVERFLOW\n");
+            ReplyReadOffset = header->ReplyWriteOffset;
+            SemReset(16+InstanceID);
+            MPQueue->unlock();
+            return 0;
+        }
+
+        if ((pktheader.SenderID == InstanceID) || // packet we sent out (shouldn't happen, but hey)
+            (pktheader.Timestamp < (timestamp - 32))) // stale packet
+        {
+            // skip this packet
+            ReplyReadOffset += pktheader.Length;
+            if (ReplyReadOffset >= kReplyEnd)
+                ReplyReadOffset += kReplyStart - kReplyEnd;
+
+            MPQueue->unlock();
+            continue;
+        }
+
+        if (pktheader.Length)
+        {
+            u32 aid = (pktheader.Type >> 16);
+            FIFORead(1, &packets[(aid-1)*1024], pktheader.Length);
+            ret |= (1 << aid);
+        }
+
+        myinstmask |= (1 << pktheader.SenderID);
+        if (((myinstmask & curinstmask) == curinstmask) ||
+            ((ret & aidmask) == aidmask))
+        {
+            // all the clients have sent their reply
+
+            MPQueue->unlock();
+            return ret;
+        }
+
+        MPQueue->unlock();
+    }
+}
+
+}
+