//----------------------------------------------------------------------------------------------------//
// @func - sys_sleep
//! @desc
//! Suspend current process for specified number of ticks
//! 1 tick = one timer interrupt received by the kernel
//! @param
//! - ms is the number of milliseconds to sleep this task.
//! @return
//! - Number of milliseconds unslept for. 0 - complete success
//! @note
//! - None
//----------------------------------------------------------------------------------------------------//
unsigned sys_sleep (unsigned int ms)
{
pid_t cpid = sys_get_currentPID();
if (add_tmr (cpid, ms) == -1)
return ms;
current_process->state = PROC_DELAY;
suspend ();
// Awaken here after timeout
return 0;
}
//----------------------------------------------------------------------------------------------------//
// @func - sys_sem_timedwait
//! @desc
//! Semaphore timedwait operation
//! - Decrement semaphore value
//! - If value < 0, block with a timeout, as specified by the second parameters 'ms'
//! @param
//! - sem is the semaphore reference
//! - ms is the amount of time to be blocked on the semaphore in milliseconds
//! @return
//! - 0 on success, -1 on failure
//! errno set to,
//! EINVAL - If the semaphore identifier does not refer to a valid semaphore
//! ETIMEDOUT - The semaphore could not be locked before the specified timeout expired.
//! EIDRM - If the semaphore was forcibly removed from the system
//! @note
//! - Depends on CONFIG_TIME being true
//----------------------------------------------------------------------------------------------------//
int sys_sem_timedwait (sem_t* sem, unsigned int ms)
{
sem_info_t* seminfo = get_sem_by_semt (sem);
process_struct *self;
if (seminfo == NULL) {
kerrno = EINVAL;
return -1;
}
seminfo->sem_value-- ; // Decrement the resource count
if (seminfo->sem_value < 0) { // If resource unavailable
self = current_process;
add_tmr (self->pid, ms); // Add a timer for self
process_block (&(seminfo->sem_wait_q), PROC_TIMED_WAIT);
// Return here on unblock
if (self->timeout) { // Timeout during semaphore wait. Return with error
seminfo->sem_value++; // Restore sem value
self->timeout = 0;
kerrno = ETIMEDOUT;
return -1;
} else {
remove_tmr (self->pid); // We managed to acquire the semaphore. Remove associated timer
}
}
// Special. Not part of posix specification. If the semaphore was force_destroy'ed
// then the process has not really acquired the semaphore when it was unblocked,
// but rather it is in an interrupted situation. Signal error in this case
if (seminfo->sem_id == -1) { // If sem invalidated by now
kerrno = EIDRM;
return -1;
}
return 0 ;
}
