/*

    SDL - Simple DirectMedia Layer

    Copyright (C) 1997-2006 Sam Lantinga

    This library is free software; you can redistribute it and/or

    modify it under the terms of the GNU Lesser General Public

    License as published by the Free Software Foundation; either

    version 2.1 of the License, or (at your option) any later version.

    This library 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

    Lesser General Public License for more details.

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

    License along with this library; if not, write to the Free Software

    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

    Sam Lantinga

    slouken@libsdl.org

*/

#include <stdio.h>

#include <time.h>

#include <sys/time.h>

#include <unistd.h>

#include <string.h>

#include <errno.h>

#include "SDL_timer.h"

static Uint32 timerStart;

/* Timer running function */

void RISCOS_CheckTimer();

#else

#include <pthread.h>

extern Uint32 riscos_main_thread;

extern int riscos_using_threads;

extern Uint32 SDL_ThreadID();

extern Uint32 SDL_EventThreadID(void);

#endif

extern void RISCOS_BackgroundTasks(void);

/* The first ticks value of the application */

clock_t start;

void SDL_StartTicks(void)

{

	/* Set first ticks value */

	start = clock();

}

Uint32 SDL_GetTicks (void)

{

	clock_t ticks;

	ticks=clock()-start;

#if CLOCKS_PER_SEC == 1000

	return(ticks);

#elif CLOCKS_PER_SEC == 100

	return (ticks * 10);

#else

	return ticks*(1000/CLOCKS_PER_SEC);

#endif

}

void SDL_Delay (Uint32 ms)

{

    Uint32 now,then,elapsed;

    int is_event_thread;

    if (riscos_using_threads)

    {

       is_event_thread = 0;

       if (SDL_EventThreadID())

       {

          if (SDL_EventThreadID() == SDL_ThreadID()) is_event_thread = 1;

       } else if (SDL_ThreadID() == riscos_main_thread) is_event_thread = 1;

    } else is_event_thread = 1;

#endif

        /*TODO: Next version of Unixlib may allow us to use usleep here */

        /*      for non event threads */

	/* Set the timeout interval - Linux only needs to do this once */

	then = SDL_GetTicks();

	do {

		/* Do background tasks required while sleeping as we are not multithreaded */

		RISCOS_BackgroundTasks();

#else

		/* For threaded build only run background tasks in event thread */

		if (is_event_thread) RISCOS_BackgroundTasks();

#endif

		/* Calculate the time interval left (in case of interrupt) */

		now = SDL_GetTicks();

		elapsed = (now-then);

		then = now;

		if ( elapsed >= ms ) {

			break;

		}

		ms -= elapsed;

            /* Need to yield to let other threads have a go */

            if (riscos_using_threads) pthread_yield();

#endif

	} while ( 1 );

}

/* Non-threaded version of timer */

int SDL_SYS_TimerInit(void)

{

	return(0);

}

void SDL_SYS_TimerQuit(void)

{

	SDL_SetTimer(0, NULL);

}

int SDL_SYS_StartTimer(void)

{

	timerStart = SDL_GetTicks();

	return(0);

}

void SDL_SYS_StopTimer(void)

{

	/* Don't need to do anything as we use SDL_timer_running

	   to detect if we need to check the timer */

}

void RISCOS_CheckTimer()

{

	if (SDL_timer_running && SDL_GetTicks() - timerStart >= SDL_alarm_interval)

	{

		Uint32 ms;

		ms = SDL_alarm_callback(SDL_alarm_interval);

		if ( ms != SDL_alarm_interval )

		{

			if ( ms )

			{

				SDL_alarm_interval = ROUND_RESOLUTION(ms);

			} else

			{

				SDL_alarm_interval = 0;

				SDL_timer_running = 0;

			}

		}

		if (SDL_alarm_interval) timerStart = SDL_GetTicks();

	}

}

#else

/* Threaded version of timer - based on code for linux */

#include "SDL_thread.h"

/* Data to handle a single periodic alarm */

static int timer_alive = 0;

static SDL_Thread *timer = NULL;

static int RunTimer(void *unused)

{

	while ( timer_alive ) {

		if ( SDL_timer_running ) {

			SDL_ThreadedTimerCheck();

		}

		SDL_Delay(1);

	}

	return(0);

}

/* This is only called if the event thread is not running */

int SDL_SYS_TimerInit(void)

{

	timer_alive = 1;

	timer = SDL_CreateThread(RunTimer, NULL);

	if ( timer == NULL )

		return(-1);

	return(SDL_SetTimerThreaded(1));

}

void SDL_SYS_TimerQuit(void)

{

	timer_alive = 0;

	if ( timer ) {

		SDL_WaitThread(timer, NULL);

		timer = NULL;

	}

}

int SDL_SYS_StartTimer(void)

{

	SDL_SetError("Internal logic error: RISC OS uses threaded timer");

	return(-1);

}

void SDL_SYS_StopTimer(void)

{

	return;

}