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>

static inline void rte_pause(void);

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

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

static __rte_always_inline void
rte_wait_until_equal_64(volatile uint64_t *addr, uint64_t expected,
        int 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,
        int memorder)
{
    assert(memorder == __ATOMIC_ACQUIRE || memorder == __ATOMIC_RELAXED);

    while (__atomic_load_n(addr, memorder) != expected)
        rte_pause();
}

static __rte_always_inline void
rte_wait_until_equal_32(volatile uint32_t *addr, uint32_t expected,
        int memorder)
{
    assert(memorder == __ATOMIC_ACQUIRE || memorder == __ATOMIC_RELAXED);

    while (__atomic_load_n(addr, memorder) != expected)
        rte_pause();
}

static __rte_always_inline void
rte_wait_until_equal_64(volatile uint64_t *addr, uint64_t expected,
        int memorder)
{
    assert(memorder == __ATOMIC_ACQUIRE || memorder == __ATOMIC_RELAXED);

    while (__atomic_load_n(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:
 *  __ATOMIC_ACQUIRE and __ATOMIC_RELAXED. These map to
 *  C++11 memory orders with the same names, see the C++11 standard or
 *  the GCC wiki on atomic synchronization for detailed definition.
 */
#define RTE_WAIT_UNTIL_MASKED(addr, mask, cond, expected, memorder) do { \
    RTE_BUILD_BUG_ON(!__builtin_constant_p(memorder));               \
    RTE_BUILD_BUG_ON(memorder != __ATOMIC_ACQUIRE &&                 \
        memorder != __ATOMIC_RELAXED);                           \
    typeof(*(addr)) expected_value = (expected);                     \
    while (!((__atomic_load_n((addr), (memorder)) & (mask)) cond     \
            expected_value))                                 \
        rte_pause();                                             \
} while (0)
#endif /* ! RTE_WAIT_UNTIL_EQUAL_ARCH_DEFINED */

#endif /* _RTE_PAUSE_H_ */