/*
    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_WINCE

#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#include <mmsystem.h>

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

static Uint64 start_date;
static Uint64 start_ticks;

static Uint64
wce_ticks (void)
{
    return ((Uint64) GetTickCount ());
}

static Uint64
wce_date (void)
{
    union
    {
        FILETIME ftime;
        Uint64 itime;
    } ftime;
    SYSTEMTIME stime;

    GetSystemTime (&stime);
    SystemTimeToFileTime (&stime, &ftime.ftime);
    ftime.itime /= 10000;       // Convert 100ns intervals to 1ms intervals
    // Remove ms portion, which can't be relied on
    ftime.itime -= (ftime.itime % 1000);
    return (ftime.itime);
}

static Sint32
wce_rel_ticks (void)
{
    return ((Sint32) (wce_ticks () - start_ticks));
}

static Sint32
wce_rel_date (void)
{
    return ((Sint32) (wce_date () - start_date));
}

/* Return time in ms relative to when SDL was started */
Uint32
SDL_GetTicks ()
{
    Sint32 offset = wce_rel_date () - wce_rel_ticks ();
    if ((offset < -1000) || (offset > 1000)) {
//    fprintf(stderr,"Time desync(%+d), resyncing\n",offset/1000);
        start_ticks -= offset;
    }

    return ((Uint32) wce_rel_ticks ());
}

/* Give up approx. givem milliseconds to the OS. */
void
SDL_Delay (Uint32 ms)
{
    Sleep (ms);
}

/* Recard start-time of application for reference */
void
SDL_StartTicks (void)
{
    start_date = wce_date ();
    start_ticks = wce_ticks ();
}

static UINT WIN_timer;

#if ( _WIN32_WCE <= 420 )

static HANDLE timersThread = 0;
static HANDLE timersQuitEvent = 0;

DWORD
TimersThreadProc (void *data)
{
    while (WaitForSingleObject (timersQuitEvent, 10) == WAIT_TIMEOUT) {
        SDL_ThreadedTimerCheck ();
    }
    return 0;
}

int
SDL_SYS_TimerInit (void)
{
    // create a thread to process a threaded timers
    // SetTimer does not suit the needs because 
    // TimerCallbackProc will be called only when WM_TIMER occured

    timersQuitEvent = CreateEvent (0, TRUE, FALSE, 0);
    if (!timersQuitEvent) {
        SDL_SetError ("Cannot create event for timers thread");
        return -1;
    }
    timersThread = CreateThread (NULL, 0, TimersThreadProc, 0, 0, 0);
    if (!timersThread) {
        SDL_SetError
            ("Cannot create timers thread, check amount of RAM available");
        return -1;
    }
    SetThreadPriority (timersThread, THREAD_PRIORITY_HIGHEST);

    return (SDL_SetTimerThreaded (1));
}

void
SDL_SYS_TimerQuit (void)
{
    SetEvent (timersQuitEvent);
    if (WaitForSingleObject (timersThread, 2000) == WAIT_TIMEOUT)
        TerminateThread (timersThread, 0);
    CloseHandle (timersThread);
    CloseHandle (timersQuitEvent);
    return;
}

#else

#pragma comment(lib, "mmtimer.lib")

/* Data to handle a single periodic alarm */
static UINT timerID = 0;

static void CALLBACK
HandleAlarm (UINT uID, UINT uMsg, DWORD dwUser, DWORD dw1, DWORD dw2)
{
    SDL_ThreadedTimerCheck ();
}


int
SDL_SYS_TimerInit (void)
{
    MMRESULT result;

    /* Set timer resolution */
    result = timeBeginPeriod (TIMER_RESOLUTION);
    if (result != TIMERR_NOERROR) {
        SDL_SetError ("Warning: Can't set %d ms timer resolution",
                      TIMER_RESOLUTION);
    }
    /* Allow 10 ms of drift so we don't chew on CPU */
    timerID =
        timeSetEvent (TIMER_RESOLUTION, 1, HandleAlarm, 0, TIME_PERIODIC);
    if (!timerID) {
        SDL_SetError ("timeSetEvent() failed");
        return (-1);
    }
    return (SDL_SetTimerThreaded (1));
}

void
SDL_SYS_TimerQuit (void)
{
    if (timerID) {
        timeKillEvent (timerID);
    }
    timeEndPeriod (TIMER_RESOLUTION);
}

#endif

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

void
SDL_SYS_StopTimer (void)
{
    return;
}

#endif /* SDL_TIMER_WINCE */
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