NAME

AG_Time — agar time interface

SYNOPSIS

#include <agar/core.h>

DESCRIPTION

These functions provide a low-level interface to monotonically increasing time sources. Different time backends may be implemented (see INTERNAL API below). Agar provides the following backends:

agTimeOps_dummy

No-op (timers will be unavailable).

agTimeOps_gettimeofday

BSD-style gettimeofday() interface.

agTimeOps_posix

The POSIX clock_gettime() interface.

agTimeOps_renderer

Monotonic clock which stops while graphical rendering is performed. This is useful for applications performing offline rendering, where the render may be influenced by different threads relying on Agar timers or AG_Delay() calls. It requires the POSIX clock_gettime() interface.

agTimeOps_win32

The MS Windows winmm API.

INTERFACE

Uint32
AG_GetTicks(void);

void
AG_Delay(Uint32 t);

void
AG_SetTimeOps(const AG_TimeOps *ops);

The AG_GetTicks() function returns the current time in ticks. One tick usually corresponds to one millisecond.

The AG_Delay() function blocks the current thread, waiting at least t ticks before returning. The exact amount of time which AG_Delay() waits is platform and backend dependent.

The AG_SetTimeOps() function selects a time backend (see below).

BACKEND INTERFACE

The argument to AG_SetTimeOps() should point to the following structure:

typedef struct ag_time_ops {
	const char *name;
	void   (*Init)(void);
	void   (*Destroy)(void);
	Uint32 (*GetTicks)(void);
	void   (*Delay)(Uint32);
} AG_TimeOps;

Init() performs any necessary initialization. Destroy() cleans up any allocated resources.

The GetTicks() operation is the backend to AG_GetTicks() and Delay() is the backend to AG_Delay().

EXAMPLES

The following code uses AG_GetTicks() to estimate the running time of a routine:

Uint32 t1, t2;

t1 = AG_GetTicks();
MyFunc();
t2 = AG_GetTicks();

AG_Verbose("MyFunc() ran for %u ticks\n",
    t2 - t1);

The following code selects the rendering-aware time backend agTimeOps_renderer if it's available:

#include <agar/config/have_clock_gettime.h>
#include <agar/config/have_pthreads.h>

#if defined(HAVE_CLOCK_GETTIME) && \
    defined(HAVE_PTHREADS)
AG_SetTimeOps(&agTimeOps_renderer);
#endif

SEE ALSO

AG_Intro(3), AG_Timer(3)

HISTORY

The AG_Time interface first appeared in Agar 1.3.4.