839b63546d
Add helpers to subtract two timespecs, then return the difference in either milliseconds or nanoseconds. These will be used to compare timestamps during the repaint cycle. Signed-off-by: Daniel Stone <daniels@collabora.com> Suggested-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk> Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
148 lines
3.7 KiB
C
148 lines
3.7 KiB
C
/*
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* Copyright © 2014 - 2015 Collabora, Ltd.
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sublicense, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice (including the
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* next paragraph) shall be included in all copies or substantial
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* portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
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* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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#ifndef TIMESPEC_UTIL_H
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#define TIMESPEC_UTIL_H
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#include <stdint.h>
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#include <assert.h>
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#define NSEC_PER_SEC 1000000000
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/* Subtract timespecs
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*
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* \param r[out] result: a - b
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* \param a[in] operand
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* \param b[in] operand
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*/
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static inline void
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timespec_sub(struct timespec *r,
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const struct timespec *a, const struct timespec *b)
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{
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r->tv_sec = a->tv_sec - b->tv_sec;
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r->tv_nsec = a->tv_nsec - b->tv_nsec;
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if (r->tv_nsec < 0) {
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r->tv_sec--;
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r->tv_nsec += NSEC_PER_SEC;
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}
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}
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/* Add a nanosecond value to a timespec
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*
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* \param r[out] result: a + b
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* \param a[in] base operand as timespec
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* \param b[in] operand in nanoseconds
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*/
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static inline void
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timespec_add_nsec(struct timespec *r, const struct timespec *a, int64_t b)
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{
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r->tv_sec = a->tv_sec + (b / NSEC_PER_SEC);
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r->tv_nsec = a->tv_nsec + (b % NSEC_PER_SEC);
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if (r->tv_nsec >= NSEC_PER_SEC) {
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r->tv_sec++;
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r->tv_nsec -= NSEC_PER_SEC;
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} else if (r->tv_nsec < 0) {
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r->tv_sec--;
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r->tv_nsec += NSEC_PER_SEC;
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}
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}
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/* Add a millisecond value to a timespec
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*
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* \param r[out] result: a + b
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* \param a[in] base operand as timespec
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* \param b[in] operand in milliseconds
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*/
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static inline void
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timespec_add_msec(struct timespec *r, const struct timespec *a, int64_t b)
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{
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return timespec_add_nsec(r, a, b * 1000000);
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}
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/* Convert timespec to nanoseconds
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*
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* \param a timespec
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* \return nanoseconds
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*/
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static inline int64_t
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timespec_to_nsec(const struct timespec *a)
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{
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return (int64_t)a->tv_sec * NSEC_PER_SEC + a->tv_nsec;
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}
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/* Subtract timespecs and return result in nanoseconds
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*
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* \param a[in] operand
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* \param b[in] operand
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* \return to_nanoseconds(a - b)
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*/
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static inline int64_t
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timespec_sub_to_nsec(const struct timespec *a, const struct timespec *b)
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{
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struct timespec r;
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timespec_sub(&r, a, b);
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return timespec_to_nsec(&r);
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}
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/* Convert timespec to milliseconds
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*
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* \param a timespec
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* \return milliseconds
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*
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* Rounding to integer milliseconds happens always down (floor()).
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*/
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static inline int64_t
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timespec_to_msec(const struct timespec *a)
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{
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return (int64_t)a->tv_sec * 1000 + a->tv_nsec / 1000000;
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}
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/* Subtract timespecs and return result in milliseconds
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*
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* \param a[in] operand
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* \param b[in] operand
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* \return to_milliseconds(a - b)
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*/
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static inline int64_t
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timespec_sub_to_msec(const struct timespec *a, const struct timespec *b)
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{
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return timespec_sub_to_nsec(a, b) / 1000000;
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}
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/* Convert milli-Hertz to nanoseconds
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*
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* \param mhz frequency in mHz, not zero
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* \return period in nanoseconds
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*/
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static inline int64_t
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millihz_to_nsec(uint32_t mhz)
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{
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assert(mhz > 0);
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return 1000000000000LL / mhz;
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}
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#endif /* TIMESPEC_UTIL_H */
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