/*
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* BlueALSA - rt.h
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* Copyright (c) 2016-2018 Arkadiusz Bokowy
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*
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* This file is a part of bluez-alsa.
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*
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* This project is licensed under the terms of the MIT license.
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*
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*/
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#ifndef BLUEALSA_SHARED_RT_H_
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#define BLUEALSA_SHARED_RT_H_
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#include <stdint.h>
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#include <time.h>
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/**
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* Structure used for time synchronization.
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*
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* With the size of the frame counter being 32 bits, it is possible to track
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* up to ~24 hours, with the sampling rate of 48 kHz. If it is insufficient,
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* one can switch to 64 bits, which would suffice for 12 million years. */
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struct asrsync {
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/* used sampling rate */
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unsigned int rate;
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/* reference time point */
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struct timespec ts0;
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/* time-stamp from the previous sync */
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struct timespec ts;
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/* transfered frames since ts0 */
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uint32_t frames;
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/* time spent outside of the sync function */
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struct timespec ts_busy;
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/* If the asrsync_sync() returns a positive value, then this variable
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* contains an amount of time used for synchronization. Otherwise, it
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* contains an overdue time - synchronization was not possible due to
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* too much time spent outside of the sync function. */
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struct timespec ts_idle;
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};
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/**
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* Start (initialize) time synchronization.
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*
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* @param asrs Pointer to the time synchronization structure.
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* @param sr Synchronization sampling rate. */
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#define asrsync_init(asrs, sr) do { \
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(asrs)->rate = sr; \
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gettimestamp(&(asrs)->ts0); \
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(asrs)->ts = (asrs)->ts0; \
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(asrs)->frames = 0; \
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} while (0)
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int asrsync_sync(struct asrsync *asrs, unsigned int frames);
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/**
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* Get the number of microseconds spent outside of the sync function. */
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#define asrsync_get_busy_usec(asrs) \
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((asrs)->ts_busy.tv_nsec / 1000)
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/**
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* Get system monotonic time-stamp.
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*
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* @param ts Address to the timespec structure where the time-stamp will
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* be stored.
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* @return On success this function returns 0. Otherwise, -1 is returned
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* and errno is set to indicate the error. */
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#ifdef CLOCK_MONOTONIC_RAW
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# define gettimestamp(ts) clock_gettime(CLOCK_MONOTONIC_RAW, ts)
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#else
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# define gettimestamp(ts) clock_gettime(CLOCK_MONOTONIC, ts)
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#endif
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int difftimespec(
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const struct timespec *ts1,
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const struct timespec *ts2,
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struct timespec *ts);
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#endif
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