#pragma once

// KPL atomic queues

#include "kpl/macro.h"

typedef struct {
    kpl_task *_Atomic head, *tail;
    struct {
       kpl_task *_Atomic next;
    } dummy;
} kpl_task_queue;

inline 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;
}

inline 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);

typedef enum : int8_t {
    KPL_RING_QUEUE_MIN_POW2     = 4,
    KPL_RING_QUEUE_MAX_POW2     = 30
} kpl_ring_queue_pow2_sizes;

typedef struct {
    _Atomic ssize_t index;
    void *data;
} kpl_ring_queue_item;

typedef struct {
    size_t mmap_size, items_mask;
    _Atomic ssize_t head_index, tail_index;
    kpl_ring_queue_item *items;
} kpl_ring_queue;

bool kpl_ring_queue_init(kpl_ring_queue *ring_queue, int8_t size_pow2);

inline void kpl_ring_queue_free(kpl_ring_queue *ring_queue) {
    munmap(ring_queue->items, ring_queue->mmap_size);
}

bool kpl_ring_queue_add(kpl_ring_queue *ring_queue, void *data);

void *kpl_ring_queue_next(kpl_ring_queue *ring_queue);