/**
* @brief Puts a task to sleep on the sleep queue until the next
* event is signalled for the device.
*
* @param dev Device number.
*/
int dev_wait(unsigned int dev __attribute__((unused)))
{
disable_interrupts();
tcb_t* cur_tcb = get_cur_tcb();
if(cur_tcb->holds_lock !=0){
return -EHOLDSLOCK;
}
tcb_t* sleep_queue = devices[dev].sleep_q;
if(sleep_queue == 0)
{
devices[dev].sleep_q = cur_tcb;
devices[dev].sleep_q -> sleep_queue = 0;
}
else{
while(sleep_queue -> sleep_queue !=0)
sleep_queue = sleep_queue -> sleep_queue;
sleep_queue->sleep_queue = cur_tcb;
sleep_queue = sleep_queue-> sleep_queue;
sleep_queue -> sleep_queue =0;
}
dispatch_sleep();
enable_interrupts();
return 0;
}
int mutex_lock(int mutex __attribute__((unused)))
{
tcb_t* temp;
disable_interrupts();
// if the provided mutex identifier if invalid
if(mutex > OS_NUM_MUTEX ||
gtMutex[mutex].bAvailable == TRUE) {
enable_interrupts();
return -EINVAL;
}
if(gtMutex[mutex].pHolding_Tcb == get_cur_tcb()) {
// if the current task is already holding the lock
enable_interrupts();
return -EDEADLOCK;
} else {
if(gtMutex[mutex].bLock == 0) {
// if the lock is not been locked
// set lock status and holding tcb
gtMutex[mutex].bLock = 1;
gtMutex[mutex].pHolding_Tcb = get_cur_tcb();
get_cur_tcb()->holds_lock = 1;
#ifdef HLP
get_cur_tcb()->cur_prio = 0;
#endif // HLP
gtMutex[mutex].pSleep_queue = 0;
enable_interrupts();
return 0;
} else {
// if the lock is been locked
// move the current tack to mutex sleeping queue
temp = gtMutex[mutex].pSleep_queue;
if (temp == 0)
{
gtMutex[mutex].pSleep_queue = get_cur_tcb();
} else {
// put current tcb at the end of the mutex sleeping queue
while((temp->sleep_queue) != 0) {
temp = temp->sleep_queue;
}
temp->sleep_queue = get_cur_tcb();
}
// context switch to another task
dispatch_sleep();
}
}
// the function cannot get here
return 1;
}
int mutex_lock(int mutex __attribute__((unused)))
{
disable_interrupts();
/* invalid mutex id, return error code */
if(mutex < 0 || mutex >= OS_NUM_MUTEX || gtMutex[mutex].bAvailable){
enable_interrupts();
return -EINVAL;
}
else{
tcb_t* cur_tcb = get_cur_tcb();
/* current task is already holding the lock, return error code */
if(cur_tcb == gtMutex[mutex].pHolding_Tcb){
enable_interrupts();
return -EDEADLOCK;
}
/* lock is holding by others, put current task to sleep */
else if(gtMutex[mutex].bLock){
/* put the task into sleep queue */
if(gtMutex[mutex].pSleep_queue == NULL){
gtMutex[mutex].pSleep_queue = cur_tcb;
cur_tcb->sleep_queue = NULL;
}
else{
tcb_t* tmp = gtMutex[mutex].pSleep_queue;
while(tmp->sleep_queue != NULL){
tmp = tmp->sleep_queue;
}
tmp->sleep_queue = cur_tcb;
cur_tcb->sleep_queue = NULL;
}
/* sleep & context switch */
dispatch_sleep();
}
/* no one's holding it, get go! */
gtMutex[mutex].pHolding_Tcb = cur_tcb;
gtMutex[mutex].bLock = TRUE;
cur_tcb->holds_lock ++;
//cur_tcb->native_prio = cur_tcb->cur_prio;
//cur_tcb->cur_prio = 0;
enable_interrupts();
return 0;
}
}
int mutex_lock(int mutex_num)
{
if(debug_enabled1 == 1) printf("\tmutex::mutex_lock:: lock(%d) by tcb %d\n", mutex_num, get_cur_tcb()->cur_prio);
disable_interrupts();
//check for valid mutex number
if(mutex_num < 0 || mutex_num > mutexID) return -EINVAL;
//mutex is valid
mutex_t* mutex = >Mutex[mutex_num-1]; //mutex we are referencing
//mutex is available
if(mutex->bAvailable == TRUE) {
//acquire mutex
mutex->bLock = TRUE;
mutex->bAvailable = FALSE;
mutex->pHolding_Tcb = get_cur_tcb();
get_cur_tcb()->holds_lock++;
enable_interrupts();
return 0; //success
}
//mutex is not available
else
{
//if current task is already holding it
if(mutex->pHolding_Tcb == get_cur_tcb()) return -EDEADLOCK;
//if the sleep queue is empty
if( mutex->pSleep_queue == NULL_TCB ) mutex->pSleep_queue = get_cur_tcb();
//else sleep queue is not empty
else
{
//add to the end of the queue
tcb_t* t = mutex->pSleep_queue;
while(t->sleep_queue != NULL_TCB) t = t->sleep_queue;
t->sleep_queue = get_cur_tcb();
}
}
//sleep and wait..`
dispatch_sleep();
enable_interrupts();
return 0; //success
}
/**
* @brief Puts a task to sleep on the sleep queue until the next
* event is signalled for the device.
*
* @param dev Device number.
*/
int dev_wait(unsigned int dev __attribute__((unused)))
{
tcb_t* cur_tcb;
tcb_t* sleepQ;
disable_interrupts();
// get current tcb and sleep devices on sleep queue
cur_tcb = get_cur_tcb();
sleepQ = devices[dev].sleep_queue;
// if task is holding a lock, return error
if (cur_tcb->holds_lock != 0)
return -EHOLDSLOCK;
// add cur_tcb to head of sleep queue linked list
devices[dev].sleep_queue = cur_tcb;
cur_tcb->sleep_queue = sleepQ;
// dispatch to next task
dispatch_sleep();
return 0;
}
/*
------------------------------------------------
Function: mutex_lock
Description:
Locks the mutex if no process currently holds the
mutex, else puts the current process in sleep queue.
------------------------------------------------
*/
int mutex_lock(int mutex)
{
tcb_t* cur_tcb;
/*Getting currrently running TCB*/
cur_tcb = get_cur_tcb();
if (mutex<1 || mutex>OS_NUM_MUTEX || (gtMutex[mutex-1].bAvailable!=1)) {
return -EINVAL;
}
if (gtMutex[mutex-1].pHolding_Tcb == cur_tcb) {
return -EDEADLOCK;
}
/*Locking the current mutex, if available*/
if (gtMutex[mutex-1].bLock == 0) {
gtMutex[mutex-1].pHolding_Tcb = cur_tcb;
gtMutex[mutex-1].bLock = 1;
gtMutex[mutex-1].pHolding_Tcb->holds_lock = 1;
cur_tcb->cur_prio = 0;
return 0;
}
/* adding process to mutex sleep queue */
else {
/* If initial sleep queue is empty*/
if (gtMutex[mutex-1].pSleep_queue == 0){
cur_tcb->sleep_queue = 0;
gtMutex[mutex-1].pSleep_queue = cur_tcb;
rear[mutex-1] = cur_tcb;
}
else {
/* Attaching current head to new del_tcb and updating head*/
cur_tcb->sleep_queue = 0;
rear[mutex-1]->sleep_queue = cur_tcb;
rear[mutex-1] = cur_tcb;
}
dispatch_sleep();
return 0;
}
return 0;
}
/**
* @brief Puts a task to sleep on the sleep queue until the next
* event is signalled for the device.
*
* @param dev Device number.
*/
int dev_wait(unsigned int dev)
{
disable_interrupts();
// get the current task's tcb, no need to handle fault dev
tcb_t* current_task_tcb = get_cur_tcb();
// check if the current task holds any mutex
if (current_task_tcb->cur_prio == HLP_PRIO) {
printf("current taks has mutex on hand, cannot sleep!\n");
return EHOLDSLOCK;
}
// insert the task on the head of device sleep queue
current_task_tcb->sleep_queue = devices[dev].sleep_queue;
devices[dev].sleep_queue = current_task_tcb;
// make it sleep
dispatch_sleep();
return 0;
}
int event_wait(unsigned int dev_num) {
// Sanity checks
if (dev_num >= NUM_DEVICES) return -EINVAL;
// Prevent curr_tcb from being modified by device_update.
INT_ATOMIC_START;
// Prevent tasks from waiting if they have a mutex.
if (curr_tcb->locks_held != 0) return -EHOLDSLOCK;
// Restore device priority to its native priority.
curr_tcb->curr_prio = curr_tcb->native_prio;
// Put calling task on the device queue.
dev_enqueue(curr_tcb, dev_num);
// Sleep current task.
dispatch_sleep();
INT_ATOMIC_END;
return 0;
}
int mutex_lock(int mutex __attribute__((unused)))
{
// Get the current task
tcb_t* cur_tcb = get_cur_tcb();
mutex_t* cur_mutex = &(gtMutex[mutex]);
// Check if mutex is in range
if((mutex <0) || (mutex >= OS_NUM_MUTEX)) return EINVAL;
// Check if deadlock error
if(cur_tcb == gtMutex[mutex].pHolding_Tcb) return EDEADLOCK;
// Disable interrupts
disable_interrupts();
// If mutex is locked (blocked), wait until freed up by sleeping
while(cur_mutex->bLock == 1){
// Enable interrupts
enable_interrupts();
dispatch_sleep();
//Disable interrupts
disable_interrupts();
}
// Set holding Tcb to current task, set bLock = TRUE, give curr\ent task highest priority, set cur tasks's "holds_lock" val to 1
cur_mutex->bLock = 1;
cur_mutex->pHolding_Tcb = cur_tcb;
cur_tcb->cur_prio = highest_prio();
cur_tcb->holds_lock = 1;
// Enable Interrupts
enable_interrupts();
return 0;
}
int mutex_lock(int mutex __attribute__((unused)))
{
disable_interrupts();
tcb_t* cur_tcb = get_cur_tcb();
uint8_t cur_prio = get_cur_prio();
tcb_t* sleep_queue, *temp;
mutex_t *cur_mutex = &(gtMutex[mutex]);
/* check if provided mutex identifier is valid */
if(mutex > num_mutices)
{
enable_interrupts();
return EINVAL;
}
/* check if current task is holding the mutex */
if(cur_mutex->pHolding_Tcb == cur_tcb)
{
enable_interrupts();
return EDEADLOCK;
}
/* check if sleep queue is empty */
if(cur_mutex->pSleep_queue == 0)
{
cur_mutex->pSleep_queue = cur_tcb;
cur_tcb->sleep_queue = 0;
}
/* insert task at appropriate location in sleep queue */
else
{
sleep_queue = cur_mutex->pSleep_queue;
temp = sleep_queue;
/* insert at front of the list */
if(cur_prio < (sleep_queue->cur_prio))
{
cur_tcb->sleep_queue = cur_mutex->pSleep_queue;
cur_mutex->pSleep_queue = cur_tcb;
}
else
{
sleep_queue = sleep_queue->sleep_queue;
while(sleep_queue != 0)
{
if(cur_prio < (sleep_queue->cur_prio))
{
cur_tcb->sleep_queue = sleep_queue;
temp->sleep_queue = cur_tcb;
break;
}
temp = sleep_queue;
sleep_queue = sleep_queue->sleep_queue;
}
}
}
disable_interrupts();
dispatch_sleep();
enable_interrupts();
return 0;
}
