Cross-platform semaphore implementation. (#43)

UnleashedRecomp/cpu/guest_thread.cpp

@@ -59,12 +59,14 @@ GuestThreadHandle::~GuestThreadHandle()
         thread.join();
 }
 
-void GuestThreadHandle::Wait(uint32_t timeout)
+uint32_t GuestThreadHandle::Wait(uint32_t timeout)
 {
     assert(timeout == INFINITE);
 
     if (thread.joinable())
         thread.join();
+
+    return STATUS_WAIT_0;
 }
 
 uint32_t GuestThread::Start(const GuestThreadParams& params)

UnleashedRecomp/cpu/guest_thread.h

@@ -29,7 +29,7 @@ struct GuestThreadHandle : KernelObject
     GuestThreadHandle(const GuestThreadParams& params);
     ~GuestThreadHandle() override;
 
-    void Wait(uint32_t timeout) override;
+    uint32_t Wait(uint32_t timeout) override;
 };
 
 struct GuestThread

UnleashedRecomp/kernel/imports.cpp

@@ -261,7 +261,7 @@ DWORD NtWaitForSingleObjectEx(DWORD Handle, DWORD WaitMode, DWORD Alertable, XLP
 
     if (IsKernelObject(Handle))
     {
-        GetKernelObject(Handle)->Wait(timeout);
+        return GetKernelObject(Handle)->Wait(timeout);
     }
     else
     {
@@ -271,13 +271,13 @@ DWORD NtWaitForSingleObjectEx(DWORD Handle, DWORD WaitMode, DWORD Alertable, XLP
         {
             return STATUS_USER_APC;
         }
-        else if (status)
+        else if (status == WAIT_TIMEOUT)
         {
-            return STATUS_ALERTED;
+            return STATUS_TIMEOUT;
         }
-    }
 
-    return STATUS_SUCCESS;
+        return STATUS_SUCCESS;
+    }
 }
 
 void NtWriteFile()
@@ -529,7 +529,7 @@ uint32_t KeSetAffinityThread(DWORD Thread, DWORD Affinity, XLPDWORD lpPreviousAf
     return 0;
 }
 
-struct Event : KernelObject, HostObject<XKEVENT>
+struct Event final : KernelObject, HostObject<XKEVENT>
 {
     HANDLE handle;
 
@@ -549,13 +549,69 @@ struct Event : KernelObject, HostObject<XKEVENT>
     }
 };
 
-struct Semaphore : KernelObject, HostObject<XKSEMAPHORE>
+struct Semaphore final : KernelObject, HostObject<XKSEMAPHORE>
 {
-    HANDLE handle;
+    std::atomic<uint32_t> count;
+    uint32_t maximumCount;
 
     Semaphore(XKSEMAPHORE* semaphore)
+        : count(semaphore->Header.SignalState), maximumCount(semaphore->Limit)
     {
-        handle = CreateSemaphoreA(nullptr, semaphore->Header.SignalState, semaphore->Limit, nullptr);
+    }
+
+    Semaphore(uint32_t count, uint32_t maximumCount)
+        : count(count), maximumCount(maximumCount)
+    {
+    }
+
+    uint32_t Wait(uint32_t timeout) override
+    {
+        if (timeout == 0)
+        {
+            uint32_t currentCount = count.load();
+            if (currentCount != 0)
+            {
+                if (count.compare_exchange_weak(currentCount, currentCount - 1))
+                    return STATUS_SUCCESS;
+            }
+
+            return STATUS_TIMEOUT;
+        }
+        else if (timeout == INFINITE)
+        {
+            uint32_t currentCount;
+            while (true)
+            {
+                currentCount = count.load();
+                if (currentCount != 0)
+                {
+                    if (count.compare_exchange_weak(currentCount, currentCount - 1))
+                        return STATUS_SUCCESS;
+                }
+                else
+                {
+                    count.wait(0);
+                }
+            }
+
+            return STATUS_SUCCESS;
+        }
+        else
+        {
+            assert(false && "Unhandled timeout value.");
+            return STATUS_TIMEOUT;
+        }
+    }
+
+    void Release(uint32_t releaseCount, uint32_t* previousCount)
+    {
+        if (previousCount != nullptr)
+            *previousCount = count;
+
+        assert(count + releaseCount <= maximumCount);
+
+        count += releaseCount;
+        count.notify_all();
     }
 };
 
@@ -876,27 +932,26 @@ bool KeResetEvent(XKEVENT* pEvent)
 
 DWORD KeWaitForSingleObject(XDISPATCHER_HEADER* Object, DWORD WaitReason, DWORD WaitMode, bool Alertable, XLPQWORD Timeout)
 {
-    const uint64_t timeout = GuestTimeoutToMilliseconds(Timeout);
+    const uint32_t timeout = GuestTimeoutToMilliseconds(Timeout);
-
+    assert(timeout == INFINITE);
-    HANDLE handle = nullptr;
 
     switch (Object->Type)
     {
         case 0:
         case 1:
-            handle = QueryKernelObject<Event>(*Object)->handle;
+            WaitForSingleObjectEx(QueryKernelObject<Event>(*Object)->handle, timeout, Alertable);
             break;
 
         case 5:
-            handle = QueryKernelObject<Semaphore>(*Object)->handle;
+            QueryKernelObject<Semaphore>(*Object)->Wait(timeout);
             break;
 
         default:
-            assert(false);
+            assert(false && "Unrecognized kernel object type.");
-            break;
+            return STATUS_TIMEOUT;
     }
 
-    return WaitForSingleObjectEx(handle, timeout, Alertable);
+    return STATUS_SUCCESS;
 }
 
 static std::vector<size_t> g_tlsFreeIndices;
@@ -1198,16 +1253,17 @@ uint32_t NtSetEvent(uint32_t handle, uint32_t* previousState)
 
 NTSTATUS NtCreateSemaphore(XLPDWORD Handle, XOBJECT_ATTRIBUTES* ObjectAttributes, DWORD InitialCount, DWORD MaximumCount)
 {
-    *Handle = (uint32_t)CreateSemaphoreA(nullptr, InitialCount, MaximumCount, nullptr);
+    *Handle = GetKernelHandle(CreateKernelObject<Semaphore>(InitialCount, MaximumCount));
     return STATUS_SUCCESS;
 }
 
-NTSTATUS NtReleaseSemaphore(uint32_t Handle, DWORD ReleaseCount, LONG* PreviousCount)
+NTSTATUS NtReleaseSemaphore(Semaphore* Handle, DWORD ReleaseCount, LONG* PreviousCount)
 {
-    ReleaseSemaphore((HANDLE)Handle, ReleaseCount, PreviousCount);
+    uint32_t previousCount;
+    Handle->Release(ReleaseCount, &previousCount);
 
-    if (PreviousCount)
+    if (PreviousCount != nullptr)
-        *PreviousCount = ByteSwap(*PreviousCount);
+        *PreviousCount = ByteSwap(previousCount);
 
     return STATUS_SUCCESS;
 }
@@ -1386,7 +1442,8 @@ void KfLowerIrql() { }
 uint32_t KeReleaseSemaphore(XKSEMAPHORE* semaphore, uint32_t increment, uint32_t adjustment, uint32_t wait)
 {
     auto* object = QueryKernelObject<Semaphore>(semaphore->Header);
-    return ReleaseSemaphore(object->handle, adjustment, nullptr) ? 0 : 0xFFFFFFFF;
+    object->Release(adjustment, nullptr);
+    return STATUS_SUCCESS;
 }
 
 void XAudioGetVoiceCategoryVolume()

UnleashedRecomp/kernel/xdm.h

@@ -12,9 +12,10 @@ struct KernelObject
     {
     }
 
-    virtual void Wait(uint32_t timeout) 
+    virtual uint32_t Wait(uint32_t timeout) 
     {
         assert(false && "Wait not implemented for this kernel object.");
+        return STATUS_TIMEOUT;
     }
 };