+//
+// Initialise a semaphore
+//
+void Semaphore_Init(tSemaphore *Sem, int Value, int MaxValue, const char *Module, const char *Name)
+{
+ Sem->Value = Value;
+ Sem->ModName = Module;
+ Sem->Name = Name;
+}
+//
+// Wait for items to be avaliable
+//
+int Semaphore_Wait(tSemaphore *Sem, int MaxToTake)
+{
+ tThread *us;
+ int taken;
+ if( MaxToTake < 0 ) {
+ Log_Warning("Threads", "Semaphore_Wait: User bug - MaxToTake(%i) < 0, Sem=%p(%s)",
+ MaxToTake, Sem, Sem->Name);
+ }
+
+ SHORTLOCK( &Sem->Protector );
+
+ // Check if there's already items avaliable
+ if( Sem->Value > 0 ) {
+ // Take what we need
+ if( MaxToTake && Sem->Value > MaxToTake )
+ taken = MaxToTake;
+ else
+ taken = Sem->Value;
+ Sem->Value -= taken;
+ SHORTREL( &Sem->Protector );
+ }
+ else
+ {
+ SHORTLOCK( &glThreadListLock );
+
+ // - Remove from active list
+ us = Threads_RemActive();
+ us->Next = NULL;
+ // - Mark as sleeping
+ us->Status = THREAD_STAT_SEMAPHORESLEEP;
+ us->WaitPointer = Sem;
+ us->RetStatus = MaxToTake; // Use RetStatus as a temp variable
+
+ // - Add to waiting
+ if(Sem->LastWaiting) {
+ Sem->LastWaiting->Next = us;
+ Sem->LastWaiting = us;
+ }
+ else {
+ Sem->Waiting = us;
+ Sem->LastWaiting = us;
+ }
+
+ SHORTREL( &glThreadListLock );
+ SHORTREL( &Sem->Protector );
+ while(us->Status == THREAD_STAT_SEMAPHORESLEEP) Threads_Yield();
+ // We're only woken when there's something avaliable
+ us->WaitPointer = NULL;
+
+ taken = us->RetStatus;
+
+ // Get the lock again
+ SHORTLOCK( &Sem->Protector );
+ }
+
+ // While there is space, and there are thread waiting
+ // wake the first thread and give it what it wants (or what's left)
+ while( (Sem->MaxValue == 0 || Sem->Value < Sem->MaxValue) && Sem->Signaling )
+ {
+ int given;
+ tThread *toWake = Sem->Signaling;
+
+ Sem->Signaling = Sem->Signaling->Next;
+ // Reset ->LastWaiting to NULL if we have just removed the last waiting thread
+ if( Sem->Signaling == NULL )
+ Sem->LastSignaling = NULL;
+
+ // Figure out how much to give
+ if( toWake->RetStatus && Sem->Value + toWake->RetStatus < Sem->MaxValue )
+ given = toWake->RetStatus;
+ else
+ given = Sem->MaxValue - Sem->Value;
+ Sem->Value -= given;
+
+ // Save the number we gave to the thread's status
+ toWake->RetStatus = given;
+
+ // Wake the sleeper
+ SHORTLOCK( &glThreadListLock );
+ if( toWake->Status != THREAD_STAT_ACTIVE )
+ Threads_AddActive(toWake);
+ SHORTREL( &glThreadListLock );
+ }
+ SHORTREL( &Sem->Protector );
+
+ return taken;
+}
+
+//
+// Add items to a semaphore
+//
+int Semaphore_Signal(tSemaphore *Sem, int AmmountToAdd)
+{
+ int given;
+ int added;
+
+ if( AmmountToAdd < 0 ) {
+ Log_Warning("Threads", "Semaphore_Signal: User bug - AmmountToAdd(%i) < 0, Sem=%p(%s)",
+ AmmountToAdd, Sem, Sem->Name);
+ }
+ SHORTLOCK( &Sem->Protector );
+
+ // Check if we have to block
+ if( Sem->MaxValue && Sem->Value == Sem->MaxValue )
+ {
+ tThread *us;
+ SHORTLOCK( &glThreadListLock );
+
+ // - Remove from active list
+ us = Threads_RemActive();
+ us->Next = NULL;
+ // - Mark as sleeping
+ us->Status = THREAD_STAT_SEMAPHORESLEEP;
+ us->WaitPointer = Sem;
+ us->RetStatus = AmmountToAdd; // Use RetStatus as a temp variable
+
+ // - Add to waiting
+ if(Sem->LastSignaling) {
+ Sem->LastSignaling->Next = us;
+ Sem->LastSignaling = us;
+ }
+ else {
+ Sem->Signaling = us;
+ Sem->LastSignaling = us;
+ }
+
+ SHORTREL( &glThreadListLock );
+ SHORTREL( &Sem->Protector );
+ while(us->Status == THREAD_STAT_SEMAPHORESLEEP) Threads_Yield();
+ // We're only woken when there's something avaliable
+ us->WaitPointer = NULL;
+
+ added = us->RetStatus;
+
+ // Get the lock again
+ SHORTLOCK( &Sem->Protector );
+ }
+ // Non blocking
+ else
+ {
+ // Figure out how much we need to take off
+ if( Sem->MaxValue && Sem->Value + AmmountToAdd > Sem->MaxValue)
+ added = Sem->MaxValue - Sem->Value;
+ else
+ added = AmmountToAdd;
+ Sem->Value += added;
+ }
+
+ // While there are items avaliable, and there are thread waiting
+ // wake the first thread and give it what it wants (or what's left)
+ while( Sem->Value && Sem->Waiting )
+ {
+ tThread *toWake = Sem->Waiting;
+
+ Sem->Waiting = Sem->Waiting->Next;
+ // Reset ->LastWaiting to NULL if we have just removed the last waiting thread
+ if( Sem->Waiting == NULL )
+ Sem->LastWaiting = NULL;
+
+ // Figure out how much to give
+ if( toWake->RetStatus && Sem->Value > toWake->RetStatus )
+ given = toWake->RetStatus;
+ else
+ given = Sem->Value;
+ Sem->Value -= given;
+
+ // Save the number we gave to the thread's status
+ toWake->RetStatus = given;
+
+ // Wake the sleeper
+ SHORTLOCK( &glThreadListLock );
+ if( toWake->Status != THREAD_STAT_ACTIVE )
+ Threads_AddActive(toWake);
+ SHORTREL( &glThreadListLock );
+ }
+ SHORTREL( &Sem->Protector );
+
+ return added;
+}
+
+//
+// Get the current value of a semaphore
+//
+int Semaphore_GetValue(tSemaphore *Sem)
+{
+ return Sem->Value;
+}
+