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#include "kpl.h"
void kpl_task_queue_init(kpl_task_queue *task_queue) {
__atomic_store_n(&task_queue->dummy.next, NULL, __ATOMIC_RELAXED);
__atomic_store_n(&task_queue->head, &task_queue->dummy, __ATOMIC_RELAXED);
task_queue->tail = (kpl_task*) &task_queue->dummy;
}
void kpl_task_queue_add(kpl_task_queue *task_queue, kpl_task *task) {
__atomic_store_n(&task->next, NULL, __ATOMIC_RELAXED);
kpl_task *head = __atomic_exchange_n(&task_queue->head, task, __ATOMIC_SEQ_CST);
__atomic_store_n(&head->next, task, __ATOMIC_RELEASE);
}
kpl_task *kpl_task_queue_next(kpl_task_queue *task_queue) {
kpl_task *task = NULL;
for (;;) {
kpl_task *tail = task_queue->tail, *next = __atomic_load_n(&tail->next, __ATOMIC_ACQUIRE);
if (tail == (kpl_task*) &task_queue->dummy) {
if (!next)
break;
tail = task_queue->tail = next;
next = __atomic_load_n(&tail->next, __ATOMIC_ACQUIRE);
}
if (!next) {
kpl_task *head = __atomic_load_n(&task_queue->head, __ATOMIC_ACQUIRE);
if (tail != head)
continue;
kpl_task_queue_add(task_queue, (kpl_task*) &task_queue->dummy);
next = __atomic_load_n(&tail->next, __ATOMIC_ACQUIRE);
}
if (next) {
task_queue->tail = next;
task = tail;
break;
}
}
if (task)
__atomic_store_n(&task->next, NULL, __ATOMIC_RELAXED);
return task;
}
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