adding in ecen425 RTOS final lab

ecen425/Semaphore.c

@@ -0,0 +1,61 @@
+#include "yakk.h"
+#include "clib.h"
+#include "PriorityQueue.h"
+
+extern PriorityQueue readyQueue;
+
+YKSEM* YKSemCreate(int initialValue) {
+	YKSEM* newSemaphore;
+
+	newSemaphore = getNewSem();
+	if (newSemaphore == null) exit(NEW_SEM_FAILED);
+
+	initializePriorityQueue(&(newSemaphore->queue));
+	newSemaphore->value = initialValue;
+
+	return newSemaphore;
+
+}
+
+void YKSemPend(YKSEM* semaphore) {
+
+	TCB* runningTask;
+
+	YKEnterMutex();
+	if (semaphore->value < 1) {
+		semaphore->value--;
+		runningTask = removePriorityQueue(&readyQueue);
+		runningTask->state = T_BLOCKED;
+		insertPriorityQueue((&(semaphore->queue)), runningTask);
+		YKExitMutex();
+		asm("int 0x20");
+		return;
+
+	} else {
+		semaphore->value--;
+		YKExitMutex();
+		return;
+	}
+
+}
+
+void YKSemPost(YKSEM* semaphore) {
+	
+	TCB* readyTask;
+
+	YKEnterMutex();
+	semaphore->value++;
+	readyTask = removePriorityQueue(&(semaphore->queue));
+	if (readyTask == null) {
+		YKExitMutex();
+		return;
+	}
+	readyTask->state = T_READY;
+	insertPriorityQueue(&readyQueue, readyTask);
+	YKExitMutex();
+	if (YKGetISRCallDepth() == 0) {
+		asm("int 0x20");
+	}
+	return;
+
+}