OS_RESULT os_mut_wait (OS_ID mutex, U16 timeout) {
/* Wait for a mutex, continue when mutex is free. */
P_MUCB p_MCB = mutex;
tsk_lock();
if (p_MCB->level == 0) {
p_MCB->owner = os_runtask;
p_MCB->prio = os_runtask->prio;
goto inc;
}
if (p_MCB->owner == os_runtask) {
/* OK, running task is the owner of this mutex. */
inc:p_MCB->level++;
tsk_unlock();
return (OS_R_OK);
}
/* Mutex owned by another task, wait until released. */
if (timeout == 0) {
goto rto;
}
/* Raise the owner task priority if lower than current priority. */
/* This priority inversion is called priority inheritance. */
if (p_MCB->prio < os_runtask->prio) {
p_MCB->owner->prio = os_runtask->prio;
os_resort_prio (p_MCB->owner);
}
if (p_MCB->p_lnk != NULL) {
os_put_prio ((P_XCB)p_MCB, os_runtask);
}
else {
p_MCB->p_lnk = os_runtask;
os_runtask->p_lnk = NULL;
os_runtask->p_rlnk = (P_TCB)p_MCB;
}
if (os_block(timeout, WAIT_MUT) == OS_R_TMO) {
rto:tsk_unlock();
return (OS_R_TMO);
}
/* A mutex has been released. */
tsk_unlock();
return (OS_R_MUT);
}
OS_RESULT os_tsk_prio (OS_TID task_id, U8 new_prio) {
/* Change execution priority of a task to "new_prio". */
P_TCB p_task;
tsk_lock();
if (task_id == 0) {
/* Change execution priority of calling task. */
os_runtask->prio = new_prio;
os_runtask->prio_base = new_prio;
run:if (os_rdy_prio() > new_prio) {
os_put_prio (&os_rdy, os_runtask);
os_runtask->state = READY;
os_dispatch (NULL);
}
tsk_unlock();
return (OS_R_OK);
}
/* Find the task in the "os_active_TCB" array. */
if (task_id > os_maxtaskrun || os_active_TCB[task_id-1] == NULL) {
/* Task with "task_id" not found or not started. */
tsk_unlock ();
return (OS_R_NOK);
}
p_task = os_active_TCB[task_id-1];
p_task->prio = new_prio;
p_task->prio_base = new_prio;
if (p_task == os_runtask) {
goto run;
}
os_resort_prio (p_task);
if (p_task->state == READY) {
/* Task enqueued in a ready list. */
p_task = os_get_first (&os_rdy);
os_dispatch (p_task);
}
tsk_unlock ();
return (OS_R_OK);
}
