SDL_systimer.c

/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997-2010 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 "SDL_config.h"

#ifdef SDL_TIMER_RISCOS

#include <stdio.h>
#include <time.h>
#include <sys/time.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>

#include "SDL_timer.h"
#include "../SDL_timer_c.h"

#if SDL_THREADS_DISABLED
/* Timer  SDL_arraysize(Timer ),start/reset time */
static Uint32 timerStart;
/* Timer running function */
void RISCOS_CheckTimer();
#else
#include <pthread.h>
extern SDL_threadID riscos_main_thread;
extern int riscos_using_threads;
extern SDL_threadID SDL_ThreadID();
extern SDL_threadID 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;
#if !SDL_THREADS_DISABLED
    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 */
#if SDL_THREADS_DISABLED
        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;
#if !SDL_THREADS_DISABLED
        /* Need to yield to let other threads have a go */
        if (riscos_using_threads)
            pthread_yield();
#endif

    } while (1);
}

#if SDL_THREADS_DISABLED

/* 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;
}

#endif /* SDL_THREADS_DISABLED */

#endif /* SDL_TIMER_RISCOS */
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