/* Returns 1 if 'string' is a palindrom, 0 otherwise. */
int isPalindrome(char *string)
{
int result = 0; /* set to 1 if 'string' is a palindrome */
int i;
int count = 0;
/* Before finishing this function, you'll need to finish sll.c */
struct sll *halfword = sll_create();
struct sll *halfword2 = sll_create();
for (i = 0; i < (int)strlen(string)/2; i++) {
/* "string[i]" will retrieve the next character */
sll_push(halfword, string[i]);
printf("%c", sll_top(halfword));
}
printf(" ");
for (i = (int)strlen(string); i > (int)strlen(string)/2; i--) {
sll_push(halfword2, string[i]);
printf("%c", sll_top(halfword2));
}
/* This loop will help you iterate over a string one character at time */
for (i = 0; i < (int)strlen(string)/2; i++) {
if (sll_top(halfword) == sll_top(halfword2)) {
sll_pop(halfword);
sll_pop(halfword2);
count++;
}
}
printf("\n%d\n", count);
if (count == (int)strlen(string)/2) {
result = 1;
} else {
result = 0;
}
return result;
}
/*
* sleep_process_system_tick
* @return: If not NULL returns the task that is needed to be scheduled next.
* This function is called by scheduler to see if there is a task that is needed
* to wake-up at a given system tick.
*/
static TASK *sleep_process_system_tick(void)
{
TASK *tcb = NULL;
TASK *tcb_break = NULL;
for (;;)
{
/* Check if we need to schedule a sleeping task. */
if ( (sleep_scheduler.ready_tasks.head != tcb_break) &&
(current_system_tick() >= sleep_scheduler.ready_tasks.head->tick_sleep) )
{
/* Schedule this sleeping task. */
tcb = (TASK *)sll_pop(&sleep_scheduler.ready_tasks, OFFSETOF(TASK, next_sleep));
/* Task is already resumed. */
if (tcb->status != TASK_SUSPENDED)
{
/* Lets not get this task out of sleep any time soon. */
tcb->tick_sleep = MAX_WAIT;
/* Put back this task on the scheduler list. */
/* We will remove it from this list when we will resume. */
sll_push(&sleep_scheduler.ready_tasks, tcb, OFFSETOF(TASK, next_sleep));
/* Save the task at which we will need to break the search. */
tcb_break = tcb;
/* This is not the task we need. */
tcb = NULL;
/* Check if we can resume the next task. */
continue;
}
else
{
/* Task is being resumed from sleep. */
tcb->status = TASK_RESUME_SLEEP;
}
}
break;
}
/* Return the task that is needed to be scheduled. */
return (tcb);
} /* sleep_process_system_tick */
/*
* sleep_task_re_enqueue
* @tcb: Task's control block that is needed to be put back in the sleeping
* tasks list as there is a higher priority task that is needed to run before
* this task.
* @from: From where this function was called.
* This scheduler's yield function, for now this only called by scheduler API's
* when a task is needed to put back in the scheduler list as there is an other
* higher priority task.
*/
static void sleep_task_re_enqueue(TASK *tcb, uint8_t from)
{
/* Process all the cases from a task can be re/scheduled. */
switch (from)
{
case YIELD_CANNOT_RUN:
/* Just put back this task on the scheduler list. */
sll_push(&sleep_scheduler.ready_tasks, tcb, OFFSETOF(TASK, next_sleep));
/* Task is being suspended. */
tcb->status = TASK_SUSPENDED;
break;
default:
break;
}
} /* sleep_task_re_enqueue */
/*
* console_register
* @console: Console data.
* This function will register a console.
*/
void console_register(CONSOLE *console)
{
#ifndef CONFIG_SEMAPHORE
/* Lock the scheduler. */
scheduler_lock();
#else
/* Obtain the global data lock. */
OS_ASSERT(semaphore_obtain(&console_data.lock, MAX_WAIT) != SUCCESS);
/* Create a semaphore to protect this console device. */
memset(&console->lock, 0, sizeof(SEMAPHORE));
semaphore_create(&console->lock, 1, 1, SEMAPHORE_PRIORITY);
#endif
/* This utility is called by drivers for registering consoles for the
* applicable devices, so no need to check for name conflicts. */
/* Just push this file system in the list. */
sll_push(&console_data.list, console, OFFSETOF(CONSOLE, fs.next));
/* Initialize console FS data. */
console->fs.get_lock = console_lock;
console->fs.release_lock = console_unlock;
console->fs.timeout = MAX_WAIT;
/* Initialize file system condition. */
fs_condition_init(&console->fs);
#ifdef CONFIG_SEMAPHORE
/* Release the global data lock. */
semaphore_release(&console_data.lock);
#else
/* Enable scheduling. */
scheduler_unlock();
#endif
} /* console_register */
