rte_kni_fifo.h

/* SPDX-License-Identifier: BSD-3-Clause
 * Copyright(c) 2010-2014 Intel Corporation
 */



#ifdef RTE_USE_C11_MEM_MODEL
#define __KNI_LOAD_ACQUIRE(src) ({                         \
                __atomic_load_n((src), __ATOMIC_ACQUIRE);           \
        })
#define __KNI_STORE_RELEASE(dst, value) do {               \
                __atomic_store_n((dst), value, __ATOMIC_RELEASE);   \
        } while(0)
#else
#define __KNI_LOAD_ACQUIRE(src) ({                         \
                typeof (*(src)) val = *(src);                       \
                rte_smp_rmb();                                      \
                val;                                                \
        })
#define __KNI_STORE_RELEASE(dst, value) do {               \
                *(dst) = value;                                     \
                rte_smp_wmb();                                      \
        } while(0)
#endif

static void
kni_fifo_init(struct rte_kni_fifo *fifo, unsigned size)
{
        /* Ensure size is power of 2 */
        if (size & (size - 1))
                rte_panic("KNI fifo size must be power of 2\n");

        fifo->write = 0;
        fifo->read = 0;
        fifo->len = size;
        fifo->elem_size = sizeof(void *);
}

static inline unsigned
kni_fifo_put(struct rte_kni_fifo *fifo, void **data, unsigned num)
{
        unsigned i = 0;
        unsigned fifo_write = fifo->write;
        unsigned new_write = fifo_write;
        unsigned fifo_read = __KNI_LOAD_ACQUIRE(&fifo->read);

        for (i = 0; i < num; i++) {
                new_write = (new_write + 1) & (fifo->len - 1);

                if (new_write == fifo_read)
                        break;
                fifo->buffer[fifo_write] = data[i];
                fifo_write = new_write;
        }
        __KNI_STORE_RELEASE(&fifo->write, fifo_write);
        return i;
}

static inline unsigned
kni_fifo_get(struct rte_kni_fifo *fifo, void **data, unsigned num)
{
        unsigned i = 0;
        unsigned new_read = fifo->read;
        unsigned fifo_write = __KNI_LOAD_ACQUIRE(&fifo->write);

        for (i = 0; i < num; i++) {
                if (new_read == fifo_write)
                        break;

                data[i] = fifo->buffer[new_read];
                new_read = (new_read + 1) & (fifo->len - 1);
        }
        __KNI_STORE_RELEASE(&fifo->read, new_read);
        return i;
}

static inline uint32_t
kni_fifo_count(struct rte_kni_fifo *fifo)
{
        unsigned fifo_write = __KNI_LOAD_ACQUIRE(&fifo->write);
        unsigned fifo_read = __KNI_LOAD_ACQUIRE(&fifo->read);
        return (fifo->len + fifo_write - fifo_read) & (fifo->len - 1);
}