cpython/Include/pytime.h

#ifndef Py_LIMITED_API
#ifndef Py_PYTIME_H
#define Py_PYTIME_H

#include "pyconfig.h" /* include for defines */
#include "object.h"

/**************************************************************************
Symbols and macros to supply platform-independent interfaces to time related
functions and constants
**************************************************************************/
#ifdef __cplusplus
extern "C" {
#endif

#ifdef HAVE_GETTIMEOFDAY
typedef struct timeval _PyTime_timeval;
#else
typedef struct {
    time_t       tv_sec;   /* seconds since Jan. 1, 1970 */
    long         tv_usec;  /* and microseconds */
} _PyTime_timeval;
#endif

/* Structure used by time.get_clock_info() */
typedef struct {
    const char *implementation;
    int monotonic;
    int adjustable;
    double resolution;
} _Py_clock_info_t;

/* Similar to POSIX gettimeofday but cannot fail.  If system gettimeofday
 * fails or is not available, fall back to lower resolution clocks.
 */
PyAPI_FUNC(void) _PyTime_gettimeofday(_PyTime_timeval *tp);

/* Similar to _PyTime_gettimeofday() but retrieve also information on the
 * clock used to get the current time. */
PyAPI_FUNC(int) _PyTime_gettimeofday_info(
    _PyTime_timeval *tp,
    _Py_clock_info_t *info);

#define _PyTime_ADD_SECONDS(tv, interval) \
do { \
    tv.tv_usec += (long) (((long) interval - interval) * 1000000); \
    tv.tv_sec += (time_t) interval + (time_t) (tv.tv_usec / 1000000); \
    tv.tv_usec %= 1000000; \
} while (0)

#define _PyTime_INTERVAL(tv_start, tv_end) \
    ((tv_end.tv_sec - tv_start.tv_sec) + \
     (tv_end.tv_usec - tv_start.tv_usec) * 0.000001)

typedef enum {
    /* Round towards zero. */
    _PyTime_ROUND_DOWN=0,
    /* Round away from zero. */
    _PyTime_ROUND_UP
} _PyTime_round_t;

/* Convert a number of seconds, int or float, to time_t. */
PyAPI_FUNC(int) _PyTime_ObjectToTime_t(
    PyObject *obj,
    time_t *sec,
    _PyTime_round_t);

/* Convert a time_t to a PyLong. */
PyAPI_FUNC(PyObject *) _PyLong_FromTime_t(
    time_t sec);

/* Convert a PyLong to a time_t. */
PyAPI_FUNC(time_t) _PyLong_AsTime_t(
    PyObject *obj);

/* Convert a number of seconds, int or float, to a timeval structure.
   usec is in the range [0; 999999] and rounded towards zero.
   For example, -1.2 is converted to (-2, 800000). */
PyAPI_FUNC(int) _PyTime_ObjectToTimeval(
    PyObject *obj,
    time_t *sec,
    long *usec,
    _PyTime_round_t);

/* Convert a number of seconds, int or float, to a timespec structure.
   nsec is in the range [0; 999999999] and rounded towards zero.
   For example, -1.2 is converted to (-2, 800000000). */
PyAPI_FUNC(int) _PyTime_ObjectToTimespec(
    PyObject *obj,
    time_t *sec,
    long *nsec,
    _PyTime_round_t);

/* Get the time of a monotonic clock, i.e. a clock that cannot go backwards.
   The clock is not affected by system clock updates. The reference point of
   the returned value is undefined, so that only the difference between the
   results of consecutive calls is valid.

   The function never fails. _PyTime_Init() ensures that a monotonic clock
   is available and works. */
PyAPI_FUNC(void) _PyTime_monotonic(
    _PyTime_timeval *tp);

/* Similar to _PyTime_monotonic(), fill also info (if set) with information of
   the function used to get the time.

   Return 0 on success, raise an exception and return -1 on error. */
PyAPI_FUNC(int) _PyTime_monotonic_info(
    _PyTime_timeval *tp,
    _Py_clock_info_t *info);

/* Initialize time.
   Return 0 on success, raise an exception and return -1 on error. */
PyAPI_FUNC(int) _PyTime_Init(void);

#ifdef __cplusplus
}
#endif

#endif /* Py_PYTIME_H */
#endif /* Py_LIMITED_API */