school/ecen425/yakc.c

#include "clib.h"
#include "yakk.h"
#include "yaku.h"
#include "PriorityQueue.h"
#include "DelayQueue.h"

//User Accessible Variables
unsigned int YKCtxSwCount = 0;
unsigned int YKIdleCount = 0;
unsigned int YKTickCounter = 0;

//Kernel Accessible Variables
static unsigned int ISRCallDepth = 0;
TCB* currentTask = null;
PriorityQueue readyQueue;
DelayQueue delayQueue;
static TaskBlock taskBlock;
static SemBlock semBlock;
static MsgQueueBlock msgQueueBlock;
static int idleTaskStack[IDLETASKSTACKSIZE];
static enum KernelState kernelState = K_BLOCKED;

unsigned int getYKCtxSwCount() {
    return YKCtxSwCount;
}

unsigned int getYKIdleCount() {
    return YKIdleCount;
}

unsigned int getYKTickNum() {
    return YKTickCounter;
}

void setYKIdleCount(int value) {
    YKIdleCount = value;
}

void setYKCtxSwCount(int value) {
    YKCtxSwCount = value;
}

void YKEnterISR(void) {
	YKEnterMutex();
	ISRCallDepth++;
	YKExitMutex();
}

void YKExitISR(void) {
	YKEnterMutex();
	ISRCallDepth--;
	if (ISRCallDepth == 0) {
		YKExitMutex();		
		YKScheduler();
	}
	YKExitMutex();
}

unsigned int YKGetISRCallDepth(void) {
		
	return ISRCallDepth;
}

void YKInitialize(void) {

	YKEnterMutex();

	//Set up queues
	initializePriorityQueue(&readyQueue);
	initializeDelayQueue();

	//Set up Task Block
	taskBlock.nextFreeTCB == 0;
	//
		
	//Set up Idle Task
	YKNewTask(YKIdleTask, &idleTaskStack[IDLETASKSTACKSIZE], 100);
	//

	YKExitMutex();
	return;

}

void YKScheduler(void) {

	TCB* readyTask; 
	YKEnterMutex();
	if (kernelState == K_BLOCKED) return;
	readyTask = peekPriorityQueue(&readyQueue);
	if (readyTask == null) exit(READY_QUEUE_EMPTY);
	if (readyTask != currentTask) {
		currentTask = readyTask;
		currentTask->state = T_READY;
		YKCtxSwCount++;
		readyTask->state = T_RUNNING;
		YKDispatcher(readyTask);
		YKExitMutex();
		return;
	}
	YKExitMutex();
	return;
}

void YKNewTask(void (*task)(void), void* taskStack, unsigned char priority) {

	TCB* newTask;	
	
	//Obtain a TCB
	newTask = getNewTCB();
	if (newTask == null) exit(NEW_TASK_FAILED);

	//Fill TCB
	newTask->tid = 0;
	newTask->priority = priority;
	newTask->stackPointer = ((void*)((int*) taskStack - 12));
	newTask->state = T_READY;
	newTask->delayCount = 0;
	newTask->next = null;
	newTask->prev = null;

	//Set up Stack
	asm("push bx");
	asm("push cx");
	asm("mov bx, [bp+6]"); //Get address of stack
	asm("mov cx, [bp+4]"); //Get address of function pointer
	asm("mov [bx-2], word 0x0200"); //Move flag register onto the stack
	asm("mov [bx-4], word 0x0");	
	asm("mov [bx-6], cx");
	asm("pop cx");
	asm("pop bx");

	insertPriorityQueue(&readyQueue, newTask);
	asm("int 0x20");
	return; 

}

TCB* getNewTCB(void) {
	
	TCB* task;
	if (taskBlock.nextFreeTCB < MAX_TASKS + 1) {
          task = &taskBlock.TCBPool[taskBlock.nextFreeTCB++];
		return task;
	} else {
		return null;
	}

}

YKSEM* getNewSem(void) {
	
	YKSEM* semaphore;
	if (semBlock.nextFreeSem < MAX_SEMS) {
          semaphore = &semBlock.SemPool[semBlock.nextFreeSem++];
		return semaphore;
	} else {
		return null;
	}

}

YKQ* getNewQueue(void) {
	
	YKQ* messageQueue;
	if (msgQueueBlock.nextFreeQueue < MAX_QUEUES) {
		messageQueue = &msgQueueBlock.QueuePool[msgQueueBlock.nextFreeQueue++];
		return messageQueue;
	} else {
		return null;
	}

}

void YKRun(void) {

	YKEnterMutex();
	kernelState = K_RUNNING;
	YKScheduler();
	YKExitMutex();
	return;

}

void YKDelayTask(unsigned int count) {

	TCB* delayedTask;

	if (count == 0) return;

	delayedTask = removePriorityQueue(&readyQueue);
	delayedTask->state = T_BLOCKED;
	delayedTask->delayCount = count;
	insertDelayQueue(delayedTask);
	asm("int 0x20");
	return;

}

void YKTickHandler(void) {

	tickClock();

}