os_time.h

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// Copyright 2019-2022, Collabora, Ltd.
// SPDX-License-Identifier: BSL-1.0
/*!
 * @file
 * @brief  Wrapper around OS native time functions.
 *
 * These should be preferred over directly using native OS time functions in
 * potentially-portable code. Additionally, in most cases these are preferred
 * over timepoints from @ref time_state for general usage in drivers, etc.
 *
 * @author Drew DeVault <sir@cmpwn.com>
 * @author Jakob Bornecrantz <jakob@collabora.com>
 * @author Rylie Pavlik <rylie.pavlik@collabora.com>
 *
 * @ingroup aux_os
 */
 
#pragma once
 
#include "xrt/xrt_config_os.h"
#include "xrt/xrt_compiler.h"
 
#include "util/u_time.h"
 
#ifdef XRT_OS_LINUX
#include <time.h>
#include <sys/time.h>
#define XRT_HAVE_TIMESPEC
#define XRT_HAVE_TIMEVAL
 
#elif defined(XRT_OS_WINDOWS)
#if defined(XRT_ENV_MINGW)
// That define is needed before to include windows.h, to avoid a collision
// between the 'byte' type defined by windows and std::byte defined in cstddef
// since C++17
#define byte win_byte_override
#include <windows.h>
#undef byte
#endif
 
#include <time.h>
#include <timeapi.h>
#define XRT_HAVE_TIMESPEC
 
#elif defined(XRT_DOXYGEN)
#include <time.h>
#define XRT_HAVE_TIMESPEC
#define XRT_HAVE_TIMEVAL
 
#else
#error "No time support on non-Linux platforms yet."
#endif
 
#ifdef __cplusplus
extern "C" {
#endif
 
/*!
 * @defgroup aux_os_time Portable Timekeeping
 * @ingroup aux_os
 *
 * @brief Unifying wrapper around system time retrieval functions.
 */
 
 
/*!
 * @defgroup aux_os_time_extra Extra Timekeeping Utilities
 * @ingroup aux_os_time
 *
 * @brief Less-portable utility functions for manipulating system time, for
 * interoperation with platform APIs.
 */
 
/*!
 * Return a monotonic clock in nanoseconds.
 * @ingroup aux_os_time
 */
static inline uint64_t
os_monotonic_get_ns(void);
 
/*!
 * Sleep the given number of nanoseconds.
 *
 * Note that on some platforms, this may be somewhat less accurate than you might want.
 * On all platforms, the system scheduler has the final say.
 *
 * @see os_precise_sleeper
 *
 * @ingroup aux_os_time
 */
static inline void
os_nanosleep(int64_t nsec);
 
/*!
 * A structure for storing state as needed for more precise sleeping, mostly for compositor use.
 * @ingroup aux_os_time
 */
struct os_precise_sleeper;
 
/*!
 * Initialize members of @ref os_precise_sleeper.
 * @public @memberof os_precise_sleeper
 */
static inline void
os_precise_sleeper_init(struct os_precise_sleeper *ops);
 
/*!
 * De-initialize members of @ref os_precise_sleeper, and free resources, without actually freeing the given
 * pointer.
 * @public @memberof os_precise_sleeper
 */
static inline void
os_precise_sleeper_deinit(struct os_precise_sleeper *ops);
 
/*!
 * Sleep the given number of nanoseconds, trying harder to be precise.
 *
 * On some platforms, there is no way to improve sleep precision easily with some OS-specific state, so we forward
 * to os_nanosleep().
 *
 * Note that on all platforms, the system scheduler has the final say.
 *
 * @public @memberof os_precise_sleeper
 */
static inline void
os_precise_sleeper_nanosleep(struct os_precise_sleeper *ops, int32_t nsec);
 
#if defined(XRT_HAVE_TIMESPEC) || defined(XRT_DOXYGEN)
/*!
 * Convert a timespec struct to nanoseconds.
 *
 * Note that this only does the value combining, no adjustment for epochs is performed.
 *
 * @ingroup aux_os_time_extra
 */
static inline uint64_t
os_timespec_to_ns(const struct timespec *spec);
 
/*!
 * Convert an nanosecond integer to a timespec struct.
 *
 * Note that this only does the value splitting, no adjustment for epochs is performed.
 * @ingroup aux_os_time_extra
 */
static inline void
os_ns_to_timespec(uint64_t ns, struct timespec *spec);
#endif
 
#if defined(XRT_HAVE_TIMEVAL) || defined(XRT_DOXYGEN)
/*!
 * Convert a timeval struct to nanoseconds.
 * @ingroup aux_os_time_extra
 */
static inline uint64_t
os_timeval_to_ns(struct timeval *val);
#endif
 
#if defined(XRT_OS_LINUX) || defined(XRT_DOXYGEN)
/*!
 * Return a realtime clock in nanoseconds (Linux-only)
 *
 * @ingroup aux_os_time_extra
 */
static inline uint64_t
os_realtime_get_ns(void);
#endif
 
#if defined(XRT_OS_WINDOWS)
/*!
 * Return a realtime clock in nanoseconds
 *
 * @ingroup aux_os_time_extra
 */
uint64_t
os_realtime_get_ns(void);
#endif
 
#if defined(XRT_OS_WINDOWS) || defined(XRT_DOXYGEN)
/*!
 * @brief Return a qpc freq in nanoseconds.
 * @ingroup aux_os_time
 */
static inline int64_t
os_ns_per_qpc_tick_get(void);
#endif
 
 
/*
 *
 * implementations follow
 *
 */
 
static inline void
os_nanosleep(int64_t nsec)
{
#if defined(XRT_OS_LINUX)
        struct timespec spec;
        spec.tv_sec = (nsec / U_1_000_000_000);
        spec.tv_nsec = (nsec % U_1_000_000_000);
        nanosleep(&spec, NULL);
#elif defined(XRT_OS_WINDOWS)
        Sleep((DWORD)(nsec / U_TIME_1MS_IN_NS));
#endif
}
 
struct os_precise_sleeper
{
#if defined(XRT_OS_WINDOWS)
        HANDLE timer;
#else
        int unused_;
#endif
};
 
static inline void
os_precise_sleeper_init(struct os_precise_sleeper *ops)
{
#if defined(XRT_OS_WINDOWS)
        ops->timer = CreateWaitableTimer(NULL, TRUE, NULL);
#endif
}
 
static inline void
os_precise_sleeper_deinit(struct os_precise_sleeper *ops)
{
#if defined(XRT_OS_WINDOWS)
        if (ops->timer) {
                CloseHandle(ops->timer);
                ops->timer = NULL;
        }
#endif
}
 
static inline void
os_precise_sleeper_nanosleep(struct os_precise_sleeper *ops, int32_t nsec)
{
#if defined(XRT_OS_WINDOWS)
        timeBeginPeriod(1);
        if (ops->timer) {
                LARGE_INTEGER timeperiod;
                timeperiod.QuadPart = -(nsec / 100);
                if (SetWaitableTimer(ops->timer, &timeperiod, 0, NULL, NULL, FALSE)) {
                        // OK we could set up the timer, now let's wait.
                        WaitForSingleObject(ops->timer, INFINITE);
                        timeEndPeriod(1);
                        return;
                }
        }
#endif
        // If we fall through from an implementation, or there's no implementation needed for a platform, we
        // delegate to the regular os_nanosleep.
        os_nanosleep(nsec);
 
#if defined(XRT_OS_WINDOWS)
        timeEndPeriod(1);
#endif
}
 
#if defined(XRT_HAVE_TIMESPEC)
static inline uint64_t
os_timespec_to_ns(const struct timespec *spec)
{
        uint64_t ns = 0;
        ns += (uint64_t)spec->tv_sec * U_1_000_000_000;
        ns += (uint64_t)spec->tv_nsec;
        return ns;
}
 
static inline void
os_ns_to_timespec(uint64_t ns, struct timespec *spec)
{
        spec->tv_sec = (ns / U_1_000_000_000);
        spec->tv_nsec = (ns % U_1_000_000_000);
}
#endif // XRT_HAVE_TIMESPEC
 
 
#if defined(XRT_HAVE_TIMEVAL) && defined(XRT_OS_LINUX)
 
#define OS_NS_PER_USEC (1000)
 
static inline uint64_t
os_timeval_to_ns(struct timeval *val)
{
        uint64_t ns = 0;
        ns += (uint64_t)val->tv_sec * U_1_000_000_000;
        ns += (uint64_t)val->tv_usec * OS_NS_PER_USEC;
        return ns;
}
#endif // defined(XRT_HAVE_TIMEVAL) && defined(XRT_OS_LINUX)
 
#if defined(XRT_OS_WINDOWS)
static inline int64_t
os_ns_per_qpc_tick_get(void)
{
        static int64_t ns_per_qpc_tick = 0;
        if (ns_per_qpc_tick == 0) {
                // Fixed at startup, so we can cache this.
                LARGE_INTEGER freq;
                QueryPerformanceFrequency(&freq);
                ns_per_qpc_tick = U_1_000_000_000 / freq.QuadPart;
        }
        return ns_per_qpc_tick;
}
#endif // defined(XRT_OS_WINDOWS)
 
static inline uint64_t
os_monotonic_get_ns(void)
{
#if defined(XRT_OS_LINUX)
        struct timespec ts;
        int ret = clock_gettime(CLOCK_MONOTONIC, &ts);
        if (ret != 0) {
                return 0;
        }
 
        return os_timespec_to_ns(&ts);
#elif defined(XRT_OS_WINDOWS)
        LARGE_INTEGER qpc;
        QueryPerformanceCounter(&qpc);
        return qpc.QuadPart * os_ns_per_qpc_tick_get();
#else
#error "need port"
#endif
}
 
#ifdef XRT_OS_LINUX
static inline uint64_t
os_realtime_get_ns(void)
{
        struct timespec ts;
        int ret = clock_gettime(CLOCK_REALTIME, &ts);
        if (ret != 0) {
                return 0;
        }
 
        return os_timespec_to_ns(&ts);
}
#endif
 
 
#ifdef __cplusplus
}
#endif