/*
   * Copyright © 2014 - 2015 Collabora, Ltd.
   *
   * Permission is hereby granted, free of charge, to any person obtaining
   * a copy of this software and associated documentation files (the
   * "Software"), to deal in the Software without restriction, including
   * without limitation the rights to use, copy, modify, merge, publish,
   * distribute, sublicense, and/or sell copies of the Software, and to
   * permit persons to whom the Software is furnished to do so, subject to
   * the following conditions:
   *
   * The above copyright notice and this permission notice (including the
   * next paragraph) shall be included in all copies or substantial
   * portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
   * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
   * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
   * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
   * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
   * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
   * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
   * SOFTWARE.
   */
  
  #ifndef TIMESPEC_UTIL_H
  #define TIMESPEC_UTIL_H
  
  #include <stdint.h>
  #include <assert.h>
  #include <time.h>
  #include <stdbool.h>
  
  #define NSEC_PER_SEC 1000000000
  
  /* Subtract timespecs
   *
   * \param r[out] result: a - b
   * \param a[in] operand
   * \param b[in] operand
   */
  static inline void
  timespec_sub(struct timespec *r,
  		const struct timespec *a, const struct timespec *b)
  {
  	r->tv_sec  = a->tv_sec - b->tv_sec;
  	r->tv_nsec = a->tv_nsec - b->tv_nsec;
  	if (r->tv_nsec < 0)
  	{
  		r->tv_sec--;
  		r->tv_nsec += NSEC_PER_SEC;
  	}
  }
  
  /* Add a nanosecond value to a timespec
   *
   * \param r[out] result: a + b
   * \param a[in] base operand as timespec
   * \param b[in] operand in nanoseconds
   */
  static inline void
  timespec_add_nsec(struct timespec *r, const struct timespec *a, int64_t b)
  {
  	r->tv_sec  = a->tv_sec + (b / NSEC_PER_SEC);
  	r->tv_nsec = a->tv_nsec + (b % NSEC_PER_SEC);
  
  	if (r->tv_nsec >= NSEC_PER_SEC)
  	{
  		r->tv_sec++;
  		r->tv_nsec -= NSEC_PER_SEC;
  	}
  	else if (r->tv_nsec < 0)
  	{
  		r->tv_sec--;
  		r->tv_nsec += NSEC_PER_SEC;
  	}
  }
  
  /* Add a millisecond value to a timespec
   *
   * \param r[out] result: a + b
   * \param a[in] base operand as timespec
   * \param b[in] operand in milliseconds
   */
  static inline void
  timespec_add_msec(struct timespec *r, const struct timespec *a, int64_t b)
  {
  	timespec_add_nsec(r, a, b * 1000000);
  }
  
  /* Convert timespec to nanoseconds
   *
   * \param a timespec
   * \return nanoseconds
   */
  static inline int64_t
  timespec_to_nsec(const struct timespec *a)
  {
  	return (int64_t) a->tv_sec * NSEC_PER_SEC + a->tv_nsec;
  }
  
  /* Subtract timespecs and return result in nanoseconds
   *
   * \param a[in] operand
   * \param b[in] operand
   * \return to_nanoseconds(a - b)
   */
  static inline int64_t
  timespec_sub_to_nsec(const struct timespec *a, const struct timespec *b)
  {
  	struct timespec r;
  	timespec_sub(&r, a, b);
  	return timespec_to_nsec(&r);
  }
  
  /* Convert timespec to milliseconds
   *
   * \param a timespec
   * \return milliseconds
   *
   * Rounding to integer milliseconds happens always down (floor()).
   */
  static inline int64_t
  timespec_to_msec(const struct timespec *a)
  {
  	return (int64_t) a->tv_sec * 1000 + a->tv_nsec / 1000000;
  }
  
  /* Subtract timespecs and return result in milliseconds
   *
   * \param a[in] operand
   * \param b[in] operand
   * \return to_milliseconds(a - b)
   */
  static inline int64_t
  timespec_sub_to_msec(const struct timespec *a, const struct timespec *b)
  {
  	return timespec_sub_to_nsec(a, b) / 1000000;
  }
  
  /* Convert timespec to microseconds
   *
   * \param a timespec
   * \return microseconds
   *
   * Rounding to integer microseconds happens always down (floor()).
   */
  static inline int64_t
  timespec_to_usec(const struct timespec *a)
  {
  	return (int64_t) a->tv_sec * 1000000 + a->tv_nsec / 1000;
  }
  
  /* Convert timespec to protocol data
   *
   * \param a timespec
   * \param tv_sec_hi[out] the high bytes of the seconds part
   * \param tv_sec_lo[out] the low bytes of the seconds part
   * \param tv_nsec[out] the nanoseconds part
   *
   * The input timespec must be normalized (the nanoseconds part should
   * be less than 1 second) and non-negative.
   */
  static inline void
  timespec_to_proto(const struct timespec *a, uint32_t *tv_sec_hi,
  		uint32_t *tv_sec_lo, uint32_t *tv_nsec)
  {
  	assert(a->tv_sec >= 0);
  	assert(a->tv_nsec >= 0 && a->tv_nsec < NSEC_PER_SEC);
  
  	uint64_t sec64 = a->tv_sec;
  
  	*tv_sec_hi = sec64 >> 32;
  	*tv_sec_lo = sec64 & 0xffffffff;
  	*tv_nsec   = a->tv_nsec;
  }
  
  /* Convert nanoseconds to timespec
   *
   * \param a timespec
   * \param b nanoseconds
   */
  static inline void
  timespec_from_nsec(struct timespec *a, int64_t b)
  {
  	a->tv_sec  = b / NSEC_PER_SEC;
  	a->tv_nsec = b % NSEC_PER_SEC;
  }
  
  /* Convert microseconds to timespec
   *
   * \param a timespec
   * \param b microseconds
   */
  static inline void
  timespec_from_usec(struct timespec *a, int64_t b)
  {
  	timespec_from_nsec(a, b * 1000);
  }
  
  /* Convert milliseconds to timespec
   *
   * \param a timespec
   * \param b milliseconds
   */
  static inline void
  timespec_from_msec(struct timespec *a, int64_t b)
  {
  	timespec_from_nsec(a, b * 1000000);
  }
  
  /* Convert protocol data to timespec
   *
   * \param a[out] timespec
   * \param tv_sec_hi the high bytes of seconds part
   * \param tv_sec_lo the low bytes of seconds part
   * \param tv_nsec the nanoseconds part
   */
  static inline void
  timespec_from_proto(struct timespec *a, uint32_t tv_sec_hi,
  		uint32_t tv_sec_lo, uint32_t tv_nsec)
  {
  	a->tv_sec  = ((uint64_t) tv_sec_hi << 32) + tv_sec_lo;
  	a->tv_nsec = tv_nsec;
  }
  
  /* Check if a timespec is zero
   *
   * \param a timespec
   * \return whether the timespec is zero
   */
  static inline bool
  timespec_is_zero(const struct timespec *a)
  {
  	return a->tv_sec == 0 && a->tv_nsec == 0;
  }
  
  /* Check if two timespecs are equal
   *
   * \param a[in] timespec to check
   * \param b[in] timespec to check
   * \return whether timespecs a and b are equal
   */
  static inline bool
  timespec_eq(const struct timespec *a, const struct timespec *b)
  {
  	return a->tv_sec == b->tv_sec &&
  		   a->tv_nsec == b->tv_nsec;
  }
  
  /* Convert milli-Hertz to nanoseconds
   *
   * \param mhz frequency in mHz, not zero
   * \return period in nanoseconds
   */
  static inline int64_t
  millihz_to_nsec(uint32_t mhz)
  {
  	assert(mhz > 0);
  	return 1000000000000LL / mhz;
  }
  
  #endif /* TIMESPEC_UTIL_H */