/* timer.h  -  Cross-platform timer library  -  Public Domain  -  2011 Mattias Jansson / Rampant Pixels
 *
 * This library provides a cross-platform interface to measure
 * elapsed time with (at least) millisecond accuracy.
 *
 * This library is put in the public domain; you can redistribute
 * it and/or modify it without any restrictions.
 *
 */

#pragma once

/*! \file timer.h
    Time measurements */

#if TIMER_COMPILE
#define TIMER_API
#else
#if __cplusplus
#define TIMER_API extern "C"
#else
#define TIMER_API extern
#endif
#endif

#if defined( _WIN32 ) || defined( _WIN64 )

//! Tick type
typedef unsigned __int64 tick_t;

#else

#include <stdint.h>
//! Tick type
typedef uint64_t         tick_t;

#endif

//! Deltatime type (float or double)
//typedef float            deltatime_t;
typedef double           deltatime_t;


/*! Initialize timer library */
TIMER_API int            timer_lib_initialize( void );

/*! Shutdown timer library */
TIMER_API void           timer_lib_shutdown( void );

/*! Get current timestamp, in ticks of system-specific frequency (queryable with timer_ticks_per_second), measured from some system-specific base timestamp
    and not in sync with other timestamps
    \return              Current timestamp */
TIMER_API tick_t         timer_current( void );

/*! Get elapsed time since given timestamp
    \param t             Timestamp
    \return              Number of seconds elapsed */
TIMER_API deltatime_t    timer_elapsed( const tick_t t );

/*! Get elapsed ticks since given timestamp
    \param t             Timestamp
    \return              Number of ticks elapsed */
TIMER_API tick_t         timer_elapsed_ticks( const tick_t t );

/*! Get timer frequency, as number of ticks per second
    \return              Ticks per second */
TIMER_API tick_t         timer_ticks_per_second( void );

/*! Get ticks as seconds (effectively calculating ticks/timer_ticks_per_second())
	\param dt            Deltatime in ticks
    \return              Deltatime in seconds */
TIMER_API deltatime_t    timer_ticks_to_seconds( const tick_t dt );

/*! Get system time, in milliseconds since the epoch (UNIX time)
    \return  Current timestamp, in milliseconds */
TIMER_API tick_t         timer_system( void );