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Kernel/Semaphores: Invert the available count checking. 

Same semantics, idea by @yuriks
This commit is contained in:
Subv 2014-12-12 22:22:11 -05:00
parent 5e25986235
commit effb181888
1 changed files with 9 additions and 11 deletions
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20
src/core/hle/kernel/semaphore.cpp
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@ -20,9 +20,8 @@ public:
static Kernel::HandleType GetStaticHandleType() { return Kernel::HandleType::Semaphore; }
Kernel::HandleType GetHandleType() const override { return Kernel::HandleType::Semaphore; }
u32 initial_count; ///< Number of entries reserved for other threads
u32 max_count; ///< Maximum number of simultaneous holders the semaphore can have
u32 current_usage; ///< Number of currently used entries in the semaphore
u32 available_count; ///< Number of free slots left in the semaphore
std::queue<Handle> waiting_threads; ///< Threads that are waiting for the semaphore
std::string name; ///< Name of semaphore (optional)
@ -31,17 +30,17 @@ public:
* @return Whether the semaphore is available
*/
bool IsAvailable() const {
return current_usage < max_count;
return available_count > 0;
}
ResultVal<bool> WaitSynchronization() override {
bool wait = current_usage == max_count;
bool wait = available_count == 0;
if (wait) {
Kernel::WaitCurrentThread(WAITTYPE_SEMA, GetHandle());
waiting_threads.push(GetCurrentThreadHandle());
} else {
++current_usage;
--available_count;
}
return MakeResult<bool>(wait);
@ -60,11 +59,10 @@ ResultCode CreateSemaphore(Handle* handle, u32 initial_count,
Semaphore* semaphore = new Semaphore;
*handle = g_object_pool.Create(semaphore);
semaphore->initial_count = initial_count;
// When the semaphore is created, some slots are reserved for other threads,
// and the rest is reserved for the caller thread
semaphore->max_count = max_count;
semaphore->current_usage = max_count - initial_count;
semaphore->available_count = initial_count;
semaphore->name = name;
return RESULT_SUCCESS;
@ -75,19 +73,19 @@ ResultCode ReleaseSemaphore(s32* count, Handle handle, s32 release_count) {
if (semaphore == nullptr)
return InvalidHandle(ErrorModule::Kernel);
if (semaphore->current_usage < release_count)
if (semaphore->max_count - semaphore->available_count < release_count)
return ResultCode(ErrorDescription::OutOfRange, ErrorModule::Kernel,
ErrorSummary::InvalidArgument, ErrorLevel::Permanent);
*count = semaphore->max_count - semaphore->current_usage;
semaphore->current_usage = semaphore->current_usage - release_count;
*count = semaphore->available_count;
semaphore->available_count += release_count;
// Notify some of the threads that the semaphore has been released
// stop once the semaphore is full again or there are no more waiting threads
while (!semaphore->waiting_threads.empty() && semaphore->IsAvailable()) {
Kernel::ResumeThreadFromWait(semaphore->waiting_threads.front());
semaphore->waiting_threads.pop();
semaphore->current_usage++;
--semaphore->available_count;
}
return RESULT_SUCCESS;