src/timer/mint/SDL_systimer.c
author Patrice Mandin <patmandin@gmail.com>
Sat, 21 Oct 2006 18:56:35 +0000
changeset 2052 eb5e61b72da3
parent 1895 c121d94672cb
child 2115 502ae1f2a577
permissions -rw-r--r--
Also save/restore fpu register in vbl interrupt

/*
    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 "SDL_config.h"

#ifdef SDL_TIMER_MINT

/*
 *	TOS/MiNT timer driver
 *	based on vbl vector
 *
 *	Patrice Mandin
 */

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

#include <mint/cookie.h>
#include <mint/sysvars.h>
#include <mint/osbind.h>
#include <mint/mintbind.h>

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

#include "SDL_vbltimer_s.h"

/* from audio/mint */
void SDL_MintAudio_CheckFpu(void);

/* The first ticks value of the application */
static Uint32 start;
static SDL_bool supervisor;
static int mint_present;        /* can we use Syield() ? */

void
SDL_StartTicks(void)
{
    void *oldpile;
    unsigned long dummy;

    /* Set first ticks value */
    oldpile = (void *) Super(0);
    start = *((volatile long *) _hz_200);
    Super(oldpile);

    start *= 5;                 /* One _hz_200 tic is 5ms */

    mint_present = (Getcookie(C_MiNT, &dummy) == C_FOUND);
}

Uint32
SDL_GetTicks(void)
{
    Uint32 now;
    void *oldpile = NULL;

    /* Check if we are in supervisor mode 
       (this is the case when called from SDL_ThreadedTimerCheck,
       which is called from RunTimer, running in the vbl vector)
     */
    if (!supervisor) {
        oldpile = (void *) Super(0);
    }

    now = *((volatile long *) _hz_200);

    if (!supervisor) {
        Super(oldpile);
    }

    return ((now * 5) - start);
}

void
SDL_Delay(Uint32 ms)
{
    Uint32 now;

    now = SDL_GetTicks();
    while ((SDL_GetTicks() - now) < ms) {
        if (mint_present) {
            Syield();
        }
    }
}

/* Data to handle a single periodic alarm */
static SDL_bool timer_installed = SDL_FALSE;

static void
RunTimer(void)
{
    supervisor = SDL_TRUE;
    SDL_ThreadedTimerCheck();
    supervisor = SDL_FALSE;
}

/* This is only called if the event thread is not running */
int
SDL_SYS_TimerInit(void)
{
    void *oldpile;

    supervisor = SDL_FALSE;

    SDL_MintAudio_CheckFpu();

    /* Install RunTimer in vbl vector */
    oldpile = (void *) Super(0);
    timer_installed = !SDL_AtariVblInstall(RunTimer);
    Super(oldpile);

    if (!timer_installed) {
        return (-1);
    }
    return (SDL_SetTimerThreaded(0));
}

void
SDL_SYS_TimerQuit(void)
{
    void *oldpile;

    if (timer_installed) {
        /* Uninstall RunTimer vbl vector */
        oldpile = (void *) Super(0);
        SDL_AtariVblUninstall(RunTimer);
        Super(oldpile);
        timer_installed = SDL_FALSE;
    }
}

int
SDL_SYS_StartTimer(void)
{
    SDL_SetError("Internal logic error: MiNT uses vbl timer");
    return (-1);
}

void
SDL_SYS_StopTimer(void)
{
    return;
}

#endif /* SDL_TIMER_MINT */
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