rte_pause.h

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/* SPDX-License-Identifier: BSD-3-Clause
 * Copyright(c) 2017 Cavium, Inc
 * Copyright(c) 2019 Arm Limited
 */

#ifndef _RTE_PAUSE_H_
#define _RTE_PAUSE_H_

#include <stdint.h>
#include <assert.h>

#include <rte_common.h>
#include <rte_atomic.h>
#include <rte_stdatomic.h>

#ifdef __cplusplus
extern "C" {
#endif

static inline void rte_pause(void);

static __rte_always_inline void
rte_wait_until_equal_16(volatile uint16_t *addr, uint16_t expected,
        rte_memory_order memorder);

static __rte_always_inline void
rte_wait_until_equal_32(volatile uint32_t *addr, uint32_t expected,
        rte_memory_order memorder);

static __rte_always_inline void
rte_wait_until_equal_64(volatile uint64_t *addr, uint64_t expected,
        rte_memory_order memorder);

#ifndef RTE_WAIT_UNTIL_EQUAL_ARCH_DEFINED
static __rte_always_inline void
rte_wait_until_equal_16(volatile uint16_t *addr, uint16_t expected,
        rte_memory_order memorder)
{
    assert(memorder == rte_memory_order_acquire || memorder == rte_memory_order_relaxed);

    while (rte_atomic_load_explicit((volatile __rte_atomic uint16_t *)addr, memorder)
            != expected)
        rte_pause();
}

static __rte_always_inline void
rte_wait_until_equal_32(volatile uint32_t *addr, uint32_t expected,
        rte_memory_order memorder)
{
    assert(memorder == rte_memory_order_acquire || memorder == rte_memory_order_relaxed);

    while (rte_atomic_load_explicit((volatile __rte_atomic uint32_t *)addr, memorder)
            != expected)
        rte_pause();
}

static __rte_always_inline void
rte_wait_until_equal_64(volatile uint64_t *addr, uint64_t expected,
        rte_memory_order memorder)
{
    assert(memorder == rte_memory_order_acquire || memorder == rte_memory_order_relaxed);

    while (rte_atomic_load_explicit((volatile __rte_atomic uint64_t *)addr, memorder)
            != expected)
        rte_pause();
}

/*
 * Wait until *addr & mask makes the condition true. With a relaxed memory
 * ordering model, the loads around this helper can be reordered.
 *
 * @param addr
 *  A pointer to the memory location.
 * @param mask
 *  A mask of value bits in interest.
 * @param cond
 *  A symbol representing the condition.
 * @param expected
 *  An expected value to be in the memory location.
 * @param memorder
 *  Two different memory orders that can be specified:
 *  rte_memory_order_acquire and rte_memory_order_relaxed.
 */
#define RTE_WAIT_UNTIL_MASKED(addr, mask, cond, expected, memorder) do { \
    RTE_BUILD_BUG_ON(!__builtin_constant_p(memorder));               \
    RTE_BUILD_BUG_ON((memorder) != rte_memory_order_acquire &&       \
        (memorder) != rte_memory_order_relaxed);                 \
    typeof(*(addr)) expected_value = (expected);                     \
    while (!((rte_atomic_load_explicit((addr), (memorder)) & (mask)) \
            cond expected_value))                            \
        rte_pause();                                             \
} while (0)
#endif /* ! RTE_WAIT_UNTIL_EQUAL_ARCH_DEFINED */

#ifdef __cplusplus
}
#endif

#endif /* _RTE_PAUSE_H_ */