matrixfurry.com
The open source OpenXR runtime
u/wait: Add wait helper
authored by
Jakob Bornecrantz
and committed by
Ryan Pavlik
a0d63d2f
29a43797
+55
src/xrt/auxiliary/util/u_wait.h
+55
src/xrt/auxiliary/util/u_wait.h
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// Copyright 2022, Collabora, Ltd.
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// SPDX-License-Identifier: BSL-1.0
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/*!
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* @file
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* @brief Tiny file to implement precise waiting functions.
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* @author Jakob Bornecrantz <jakob@collabora.com>
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* @ingroup aux_util
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*/
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#pragma once
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#include "xrt/xrt_config_os.h"
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#include "os/os_time.h"
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#if defined(XRT_DOXYGEN)
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/*!
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* OS specific tweak to wait time.
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*
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* @todo Measure on Windows.
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* @ingroup aux_util
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*/
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#define U_WAIT_MEASURED_SCHEDULER_LATENCY_NS (uint64_t)(0)
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#elif defined(XRT_OS_LINUX) || defined(XRT_OS_ANDROID)
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#define U_WAIT_MEASURED_SCHEDULER_LATENCY_NS (uint64_t)(50 * 1000)
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#elif defined(XRT_OS_WINDOWS)
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#define U_WAIT_MEASURED_SCHEDULER_LATENCY_NS (uint64_t)(0)
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#else
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#error "Unsupported platform!"
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#endif
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/*!
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* Waits until the given time using the @ref os_precise_sleeper.
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*
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* @ingroup aux_util
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*/
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static inline void
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u_wait_until(struct os_precise_sleeper *sleeper, uint64_t until_ns)
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{
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uint64_t now_ns = os_monotonic_get_ns();
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// Lets hope its not to late.
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bool fuzzy_in_the_past = time_is_less_then_or_within_range(until_ns, now_ns, U_TIME_1MS_IN_NS);
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// When we should wake up is in the past:ish.
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if (fuzzy_in_the_past) {
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return;
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}
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// Sufficiently in the future.
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uint32_t delay = (uint32_t)(until_ns - now_ns - U_WAIT_MEASURED_SCHEDULER_LATENCY_NS);
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os_precise_sleeper_nanosleep(sleeper, delay);
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}