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u/wait: Add wait helper

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Jakob Bornecrantz 2022-09-02 22:13:31 +01:00 committed by Ryan Pavlik
parent 29a43797fc
commit a0d63d2f9c
1 changed files with 55 additions and 0 deletions
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src/xrt/auxiliary/util/u_wait.h Normal file
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// Copyright 2022, Collabora, Ltd.
// SPDX-License-Identifier: BSL-1.0
/*!
* @file
* @brief Tiny file to implement precise waiting functions.
* @author Jakob Bornecrantz <jakob@collabora.com>
* @ingroup aux_util
*/
#pragma once
#include "xrt/xrt_config_os.h"
#include "os/os_time.h"
#if defined(XRT_DOXYGEN)
/*!
* OS specific tweak to wait time.
*
* @todo Measure on Windows.
* @ingroup aux_util
*/
#define U_WAIT_MEASURED_SCHEDULER_LATENCY_NS (uint64_t)(0)
#elif defined(XRT_OS_LINUX) || defined(XRT_OS_ANDROID)
#define U_WAIT_MEASURED_SCHEDULER_LATENCY_NS (uint64_t)(50 * 1000)
#elif defined(XRT_OS_WINDOWS)
#define U_WAIT_MEASURED_SCHEDULER_LATENCY_NS (uint64_t)(0)
#else
#error "Unsupported platform!"
#endif
/*!
* Waits until the given time using the @ref os_precise_sleeper.
*
* @ingroup aux_util
*/
static inline void
u_wait_until(struct os_precise_sleeper *sleeper, uint64_t until_ns)
{
uint64_t now_ns = os_monotonic_get_ns();
// Lets hope its not to late.
bool fuzzy_in_the_past = time_is_less_then_or_within_range(until_ns, now_ns, U_TIME_1MS_IN_NS);
// When we should wake up is in the past:ish.
if (fuzzy_in_the_past) {
return;
}
// Sufficiently in the future.
uint32_t delay = (uint32_t)(until_ns - now_ns - U_WAIT_MEASURED_SCHEDULER_LATENCY_NS);
os_precise_sleeper_nanosleep(sleeper, delay);
}