/* timespec -- System time interface

   Copyright (C) 2000, 2002, 2004-2005, 2007, 2009-2018 Free Software

   Foundation, Inc.

   This program is free software: you can redistribute it and/or modify

   it under the terms of the GNU General Public License as published by

   the Free Software Foundation; either version 3 of the License, or

   (at your option) any later version.

   This program is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License

   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */

#if ! defined TIMESPEC_H

# define TIMESPEC_H

# include <time.h>

#ifndef _GL_INLINE_HEADER_BEGIN

 #error "Please include config.h first."

#endif

_GL_INLINE_HEADER_BEGIN

#ifndef _GL_TIMESPEC_INLINE

# define _GL_TIMESPEC_INLINE _GL_INLINE

#endif

#ifdef __cplusplus

extern "C" {

#endif

#include "verify.h"

/* Resolution of timespec timestamps (in units per second), and log

   base 10 of the resolution.  */

enum { TIMESPEC_RESOLUTION = 1000000000 };

enum { LOG10_TIMESPEC_RESOLUTION = 9 };

/* Return a timespec with seconds S and nanoseconds NS.  */

_GL_TIMESPEC_INLINE struct timespec

make_timespec (time_t s, long int ns)

{

  struct timespec r;

  r.tv_sec = s;

  r.tv_nsec = ns;

  return r;

}

/* Return negative, zero, positive if A < B, A == B, A > B, respectively.

   For each timestamp T, this code assumes that either:

     * T.tv_nsec is in the range 0..999999999; or

     * T.tv_sec corresponds to a valid leap second on a host that supports

       leap seconds, and T.tv_nsec is in the range 1000000000..1999999999; or

     * T.tv_sec is the minimum time_t value and T.tv_nsec is -1; or

       T.tv_sec is the maximum time_t value and T.tv_nsec is 2000000000.

       This allows for special struct timespec values that are less or

       greater than all possible valid timestamps.

   In all these cases, it is safe to subtract two tv_nsec values and

   convert the result to integer without worrying about overflow on

   any platform of interest to the GNU project, since all such

   platforms have 32-bit int or wider.

   Replacing "a.tv_nsec - b.tv_nsec" with something like

   "a.tv_nsec < b.tv_nsec ? -1 : a.tv_nsec > b.tv_nsec" would cause

   this function to work in some cases where the above assumption is

   violated, but not in all cases (e.g., a.tv_sec==1, a.tv_nsec==-2,

   b.tv_sec==0, b.tv_nsec==999999999) and is arguably not worth the

   extra instructions.  Using a subtraction has the advantage of

   detecting some invalid cases on platforms that detect integer

   overflow.  */

_GL_TIMESPEC_INLINE int _GL_ATTRIBUTE_PURE

timespec_cmp (struct timespec a, struct timespec b)

{

  if (a.tv_sec < b.tv_sec)

    return -1;

  if (a.tv_sec > b.tv_sec)

    return 1;

  /* Pacify gcc -Wstrict-overflow (bleeding-edge circa 2017-10-02).  See:

     https://lists.gnu.org/r/bug-gnulib/2017-10/msg00006.html  */

  assume (-1 <= a.tv_nsec && a.tv_nsec <= 2 * TIMESPEC_RESOLUTION);

  assume (-1 <= b.tv_nsec && b.tv_nsec <= 2 * TIMESPEC_RESOLUTION);

  return a.tv_nsec - b.tv_nsec;

}

/* Return -1, 0, 1, depending on the sign of A.  A.tv_nsec must be

   nonnegative.  */

_GL_TIMESPEC_INLINE int _GL_ATTRIBUTE_PURE

timespec_sign (struct timespec a)

{

  return a.tv_sec < 0 ? -1 : a.tv_sec || a.tv_nsec;

}

struct timespec timespec_add (struct timespec, struct timespec)

  _GL_ATTRIBUTE_CONST;

struct timespec timespec_sub (struct timespec, struct timespec)

  _GL_ATTRIBUTE_CONST;

struct timespec dtotimespec (double)

  _GL_ATTRIBUTE_CONST;

/* Return an approximation to A, of type 'double'.  */

_GL_TIMESPEC_INLINE double

timespectod (struct timespec a)

{

  return a.tv_sec + a.tv_nsec / 1e9;

}

void gettime (struct timespec *);

int settime (struct timespec const *);

#ifdef __cplusplus

}

#endif

_GL_INLINE_HEADER_END

#endif