SDL/src/timer/os2/SDL_systimer.c

/*
  Simple DirectMedia Layer
  Copyright (C) 1997-2021 Sam Lantinga <slouken@libsdl.org>

  This software is provided 'as-is', without any express or implied
  warranty.  In no event will the authors be held liable for any damages
  arising from the use of this software.

  Permission is granted to anyone to use this software for any purpose,
  including commercial applications, and to alter it and redistribute it
  freely, subject to the following restrictions:

  1. The origin of this software must not be misrepresented; you must not
     claim that you wrote the original software. If you use this software
     in a product, an acknowledgment in the product documentation would be
     appreciated but is not required.
  2. Altered source versions must be plainly marked as such, and must not be
     misrepresented as being the original software.
  3. This notice may not be removed or altered from any source distribution.
*/
#include "../../SDL_internal.h"

#if SDL_TIMER_OS2

#include "SDL_timer.h"
#include "../../core/os2/SDL_os2.h"

#define INCL_DOSERRORS
#define INCL_DOSMISC
#define INCL_DOSPROFILE
#define INCL_DOSSEMAPHORES
#define INCL_DOSDATETIME
#define INCL_DOSPROCESS
#define INCL_DOSEXCEPTIONS
#include <os2.h>

/* No need to switch priorities in SDL_Delay() for OS/2 versions > Warp3 fp 42, */
/*#define _SWITCH_PRIORITY*/

typedef unsigned long long  ULLONG;

static ULONG    ulTmrFreq = 0;
static ULLONG   ullTmrStart = 0;

/* 32-bit counter fallback...not used if DosTmrQuery* is functioning. */
static ULONG    ulPrevTmr = 0;
static Uint64   ui64TmrStartOffset = 0;  /* Used if 32-bit counter overflows. */

void
SDL_TicksInit(void)
{
    ULONG ulTmrStart;  /* for 32-bit fallback. */
    ULONG ulRC = DosTmrQueryFreq(&ulTmrFreq);
    if (ulRC != NO_ERROR) {
        debug_os2("DosTmrQueryFreq() failed, rc = %u", ulRC);
    } else {
        ulRC = DosTmrQueryTime((PQWORD)&ullTmrStart);
        if (ulRC == NO_ERROR) {
            return;
        }
        debug_os2("DosTmrQueryTime() failed, rc = %u", ulRC);
    }

    ulTmrFreq = 0; /* Error - use DosQuerySysInfo() for timer. */
    DosQuerySysInfo(QSV_MS_COUNT, QSV_MS_COUNT, &ulTmrStart, sizeof (ULONG));
    ullTmrStart = (ULLONG) ulTmrStart;
    ulPrevTmr = ulTmrStart;
}

void
SDL_TicksQuit(void)
{
}

Uint64
SDL_GetTicks64(void)
{
    Uint64 ui64Result;
    ULLONG ullTmrNow;

    if (ulTmrFreq == 0) { /* Was not initialized. */
        SDL_TicksInit();
    }

    if (ulTmrFreq != 0) {
        DosTmrQueryTime((PQWORD)&ullTmrNow);
        ui64Result = (ullTmrNow - ullTmrStart) * 1000 / ulTmrFreq;
    } else {
        ULONG ulTmrNow;
        DosQuerySysInfo(QSV_MS_COUNT, QSV_MS_COUNT, &ulTmrNow, sizeof (ULONG));
        if ( ((ULLONG) ulTmrNow) < ulPrevTmr ) {  /* have we overflowed the 32-bit counter since last check? */
            /* Note that this is incorrect if you went more than ~98 days between calls to SDL_GetTicks64(). */
            /* One could query QSV_TIME_HIGH and QSV_TIME_LOW here to verify, but it's probably not worth it. */
            ui64TmrStartOffset += 0xFFFFFFFF;
        }
        ui64Result = (((Uint64) ulTmrNow) - ullTmrStart) + ui64TmrStartOffset;
        ulPrevTmr = ulTmrNow;
    }

    return ui64Result;
}

Uint64
SDL_GetPerformanceCounter(void)
{
    QWORD   qwTmrNow;

    if (ulTmrFreq == 0 || (DosTmrQueryTime(&qwTmrNow) != NO_ERROR))
        return SDL_GetTicks64();

    return *((Uint64 *)&qwTmrNow);
}

Uint64
SDL_GetPerformanceFrequency(void)
{
    return (ulTmrFreq == 0)? 1000 : (Uint64)ulTmrFreq;
}

void
SDL_Delay(Uint32 ms)
{
    HTIMER  hTimer = NULLHANDLE;
    ULONG   ulRC;
#ifdef _SWITCH_PRIORITY
    PPIB    pib;
    PTIB    tib;
    BOOL    fSetPriority = ms < 50;
    ULONG   ulSavePriority;
    ULONG   ulNesting;
#endif
    HEV     hevTimer;

    if (ms == 0) {
      DosSleep(0);
      return;
    }

    ulRC = DosCreateEventSem(NULL, &hevTimer, DC_SEM_SHARED, FALSE);
    if (ulRC != NO_ERROR) {
        debug_os2("DosAsyncTimer() failed, rc = %u", ulRC);
        DosSleep(ms);
        return;
    }

#ifdef _SWITCH_PRIORITY
    if (fSetPriority) {
        if (DosGetInfoBlocks(&tib, &pib) != NO_ERROR)
            fSetPriority = FALSE;
        else {
            ulSavePriority = tib->tib_ptib2->tib2_ulpri;
            if (((ulSavePriority & 0xFF00) == 0x0300) || /* already have high pr. */
                  (DosEnterMustComplete( &ulNesting) != NO_ERROR))
                fSetPriority = FALSE;
            else {
                DosSetPriority(PRTYS_THREAD, PRTYC_TIMECRITICAL, 0, 0);
            }
        }
    }
#endif

    DosResetEventSem(hevTimer, &ulRC);
    ulRC = DosAsyncTimer(ms, (HSEM)hevTimer, &hTimer);

#ifdef _SWITCH_PRIORITY
    if (fSetPriority) {
        if (DosSetPriority(PRTYS_THREAD, (ulSavePriority >> 8) & 0xFF, 0, 0) == NO_ERROR)
            DosSetPriority(PRTYS_THREAD, 0, ulSavePriority & 0xFF, 0);
        DosExitMustComplete(&ulNesting);
    }
#endif

    if (ulRC != NO_ERROR) {
        debug_os2("DosAsyncTimer() failed, rc = %u", ulRC);
    } else {
        DosWaitEventSem(hevTimer, SEM_INDEFINITE_WAIT);
    }

    if (ulRC != NO_ERROR)
        DosSleep(ms);

    DosCloseEventSem(hevTimer);
}

#endif /* SDL_TIMER_OS2 */

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