rte_ring_peek_elem_pvt.h

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/* SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 2010-2020 Intel Corporation
 * Copyright (c) 2007-2009 Kip Macy kmacy@freebsd.org
 * All rights reserved.
 * Derived from FreeBSD's bufring.h
 * Used as BSD-3 Licensed with permission from Kip Macy.
 */

#ifndef _RTE_RING_PEEK_ELEM_PVT_H_
#define _RTE_RING_PEEK_ELEM_PVT_H_

static __rte_always_inline uint32_t
__rte_ring_st_get_tail(struct rte_ring_headtail *ht, uint32_t *tail,
    uint32_t num)
{
    uint32_t h, n, t;

    h = ht->head;
    t = ht->tail;
    n = h - t;

    RTE_ASSERT(n >= num);
    num = (n >= num) ? num : 0;

    *tail = t;
    return num;
}

static __rte_always_inline void
__rte_ring_st_set_head_tail(struct rte_ring_headtail *ht, uint32_t tail,
    uint32_t num, uint32_t enqueue)
{
    uint32_t pos;

    RTE_SET_USED(enqueue);

    pos = tail + num;
    ht->head = pos;
    __atomic_store_n(&ht->tail, pos, __ATOMIC_RELEASE);
}

static __rte_always_inline uint32_t
__rte_ring_hts_get_tail(struct rte_ring_hts_headtail *ht, uint32_t *tail,
    uint32_t num)
{
    uint32_t n;
    union __rte_ring_hts_pos p;

    p.raw = __atomic_load_n(&ht->ht.raw, __ATOMIC_RELAXED);
    n = p.pos.head - p.pos.tail;

    RTE_ASSERT(n >= num);
    num = (n >= num) ? num : 0;

    *tail = p.pos.tail;
    return num;
}

static __rte_always_inline void
__rte_ring_hts_set_head_tail(struct rte_ring_hts_headtail *ht, uint32_t tail,
    uint32_t num, uint32_t enqueue)
{
    union __rte_ring_hts_pos p;

    RTE_SET_USED(enqueue);

    p.pos.head = tail + num;
    p.pos.tail = p.pos.head;

    __atomic_store_n(&ht->ht.raw, p.raw, __ATOMIC_RELEASE);
}

static __rte_always_inline unsigned int
__rte_ring_do_enqueue_start(struct rte_ring *r, uint32_t n,
        enum rte_ring_queue_behavior behavior, uint32_t *free_space)
{
    uint32_t free, head, next;

    switch (r->prod.sync_type) {
    case RTE_RING_SYNC_ST:
        n = __rte_ring_move_prod_head(r, RTE_RING_SYNC_ST, n,
            behavior, &head, &next, &free);
        break;
    case RTE_RING_SYNC_MT_HTS:
        n =  __rte_ring_hts_move_prod_head(r, n, behavior,
            &head, &free);
        break;
    case RTE_RING_SYNC_MT:
    case RTE_RING_SYNC_MT_RTS:
    default:
        /* unsupported mode, shouldn't be here */
        RTE_ASSERT(0);
        n = 0;
        free = 0;
    }

    if (free_space != NULL)
        *free_space = free - n;
    return n;
}

static __rte_always_inline unsigned int
__rte_ring_do_dequeue_start(struct rte_ring *r, void *obj_table,
    uint32_t esize, uint32_t n, enum rte_ring_queue_behavior behavior,
    uint32_t *available)
{
    uint32_t avail, head, next;

    switch (r->cons.sync_type) {
    case RTE_RING_SYNC_ST:
        n = __rte_ring_move_cons_head(r, RTE_RING_SYNC_ST, n,
            behavior, &head, &next, &avail);
        break;
    case RTE_RING_SYNC_MT_HTS:
        n =  __rte_ring_hts_move_cons_head(r, n, behavior,
            &head, &avail);
        break;
    case RTE_RING_SYNC_MT:
    case RTE_RING_SYNC_MT_RTS:
    default:
        /* unsupported mode, shouldn't be here */
        RTE_ASSERT(0);
        n = 0;
        avail = 0;
    }

    if (n != 0)
        __rte_ring_dequeue_elems(r, head, obj_table, esize, n);

    if (available != NULL)
        *available = avail - n;
    return n;
}

#endif /* _RTE_RING_PEEK_ELEM_PVT_H_ */