void *nano_task_lifo_get_wait(struct nano_lifo *lifo)
{
void *data;
unsigned int imask;
/* spin until data is put onto the LIFO */
while (1) {
imask = irq_lock_inline();
/*
* Predict that the branch will be taken to break out of the loop.
* There is little cost to a misprediction since that leads to idle.
*/
if (likely(lifo->list))
break;
/* see explanation in nano_stack.c:nano_task_stack_pop_wait() */
nano_cpu_atomic_idle(imask);
}
data = lifo->list;
lifo->list = *(void **) data;
irq_unlock_inline(imask);
return data;
}
void nano_task_sem_take_wait(struct nano_sem *sem)
{
unsigned int imask;
/* spin until the sempahore is signaled */
while (1) {
imask = irq_lock_inline();
/*
* Predict that the branch will be taken to break out of the loop.
* There is little cost to a misprediction since that leads to idle.
*/
if (likely(sem->nsig > 0))
break;
/* see explanation in nano_stack.c:nano_task_stack_pop_wait() */
nano_cpu_atomic_idle(imask);
}
sem->nsig--;
irq_unlock_inline(imask);
}
int nano_task_stack_pop(struct nano_stack *stack, uint32_t *pData, int32_t timeout_in_ticks)
{
unsigned int imask;
imask = irq_lock();
while (1) {
/*
* Predict that the branch will be taken to break out of the
* loop. There is little cost to a misprediction since that
* leads to idle.
*/
if (likely(stack->next > stack->base)) {
stack->next--;
*pData = *(stack->next);
irq_unlock(imask);
return 1;
}
if (timeout_in_ticks == TICKS_NONE) {
break;
}
/*
* Invoke nano_cpu_atomic_idle() with interrupts still disabled
* to prevent the scenario where an interrupt fires after
* re-enabling interrupts and before executing the "halt"
* instruction. If the ISR performs a nano_isr_stack_push() on
* the same stack object, the subsequent execution of the "halt"
* instruction will result in the queued data being ignored
* until the next interrupt, if any.
*
* Thus it should be clear that an architectures implementation
* of nano_cpu_atomic_idle() must be able to atomically
* re-enable interrupts and enter a low-power mode.
*
* This explanation is valid for all nanokernel objects: stacks,
* FIFOs, LIFOs, and semaphores, for their
* nano_task_<object>_<get>() routines.
*/
nano_cpu_atomic_idle(imask);
imask = irq_lock();
}
irq_unlock(imask);
return 0;
}
void *nano_task_lifo_get_wait_timeout(struct nano_lifo *lifo,
int32_t timeout_in_ticks)
{
int64_t cur_ticks, limit;
unsigned int key;
void *data;
if (unlikely(TICKS_UNLIMITED == timeout_in_ticks)) {
return nano_task_lifo_get_wait(lifo);
}
if (unlikely(TICKS_NONE == timeout_in_ticks)) {
return nano_task_lifo_get(lifo);
}
key = irq_lock_inline();
cur_ticks = nano_tick_get();
limit = cur_ticks + timeout_in_ticks;
while (cur_ticks < limit) {
/*
* Predict that the branch will be taken to break out of the loop.
* There is little cost to a misprediction since that leads to idle.
*/
if (likely(lifo->list)) {
data = lifo->list;
lifo->list = *(void **)data;
irq_unlock_inline(key);
return data;
}
/* see explanation in nano_stack.c:nano_task_stack_pop_wait() */
nano_cpu_atomic_idle(key);
key = irq_lock_inline();
cur_ticks = nano_tick_get();
}
irq_unlock_inline(key);
return NULL;
}
void task_sleep(int32_t timeout_in_ticks)
{
int64_t cur_ticks, limit;
int key;
key = irq_lock();
cur_ticks = sys_tick_get();
limit = cur_ticks + timeout_in_ticks;
while (cur_ticks < limit) {
_NANO_TIMEOUT_SET_TASK_TIMEOUT(timeout_in_ticks);
nano_cpu_atomic_idle(key);
key = irq_lock();
cur_ticks = sys_tick_get();
}
irq_unlock(key);
}
void *nano_task_lifo_get(struct nano_lifo *lifo, int32_t timeout_in_ticks)
{
int64_t cur_ticks;
int64_t limit = 0x7fffffffffffffffll;
unsigned int imask;
imask = irq_lock();
cur_ticks = _NANO_TIMEOUT_TICK_GET();
if (timeout_in_ticks != TICKS_UNLIMITED) {
limit = cur_ticks + timeout_in_ticks;
}
do {
/*
* Predict that the branch will be taken to break out of the loop.
* There is little cost to a misprediction since that leads to idle.
*/
if (likely(lifo->list != NULL)) {
void *data = lifo->list;
lifo->list = *(void **) data;
irq_unlock(imask);
return data;
}
if (timeout_in_ticks != TICKS_NONE) {
_NANO_TIMEOUT_SET_TASK_TIMEOUT(timeout_in_ticks);
/* see explanation in nano_stack.c:nano_task_stack_pop() */
nano_cpu_atomic_idle(imask);
imask = irq_lock();
cur_ticks = _NANO_TIMEOUT_TICK_GET();
}
} while (cur_ticks < limit);
irq_unlock(imask);
return NULL;
}
int nano_task_sem_take_wait_timeout(struct nano_sem *sem, int32_t timeout_in_ticks)
{
int64_t cur_ticks, limit;
unsigned int key;
if (unlikely(TICKS_UNLIMITED == timeout_in_ticks)) {
nano_task_sem_take_wait(sem);
return 1;
}
if (unlikely(TICKS_NONE == timeout_in_ticks)) {
return nano_task_sem_take(sem);
}
key = irq_lock_inline();
cur_ticks = nano_tick_get();
limit = cur_ticks + timeout_in_ticks;
while (cur_ticks < limit) {
/*
* Predict that the branch will be taken to break out of the loop.
* There is little cost to a misprediction since that leads to idle.
*/
if (likely(sem->nsig > 0)) {
sem->nsig--;
irq_unlock_inline(key);
return 1;
}
/* see explanation in nano_stack.c:nano_task_stack_pop_wait() */
nano_cpu_atomic_idle(key);
key = irq_lock_inline();
cur_ticks = nano_tick_get();
}
irq_unlock_inline(key);
return 0;
}