/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
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 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is the Netscape Portable Runtime (NSPR).
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 1998-2000
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *
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 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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/*
 * OS/2 interval timers
 *
 */

#include "primpl.h"

static PRBool useHighResTimer = PR_FALSE;
PRIntervalTime _os2_ticksPerSec = -1;
PRIntn _os2_bitShift = 0;
PRInt32 _os2_highMask = 0;
   
void
_PR_MD_INTERVAL_INIT()
{
    char *envp;
    ULONG timerFreq;
    APIRET rc;

    if ((envp = getenv("NSPR_OS2_NO_HIRES_TIMER")) != NULL) {
        if (atoi(envp) == 1)
           return;
    }

    timerFreq = 0; /* OS/2 high-resolution timer frequency in Hz */
    rc = DosTmrQueryFreq(&timerFreq);
    if (NO_ERROR == rc) {
        useHighResTimer = PR_TRUE;
        PR_ASSERT(timerFreq != 0);
        while (timerFreq > PR_INTERVAL_MAX) {
            timerFreq >>= 1;
            _os2_bitShift++;
            _os2_highMask = (_os2_highMask << 1)+1;
        }

        _os2_ticksPerSec = timerFreq;
        PR_ASSERT(_os2_ticksPerSec > PR_INTERVAL_MIN);
    }
}

PRIntervalTime
_PR_MD_GET_INTERVAL()
{
    if (useHighResTimer) {
        QWORD timestamp;
        PRInt32 top;
        APIRET rc = DosTmrQueryTime(&timestamp);
        if (NO_ERROR != rc) {
            return -1;
        }
        /* Sadly, nspr requires the interval to range from 1000 ticks per
         * second to only 100000 ticks per second. DosTmrQueryTime is too
         * high resolution...
         */
        top = timestamp.ulHi & _os2_highMask;
        top = top << (32 - _os2_bitShift);
        timestamp.ulLo = timestamp.ulLo >> _os2_bitShift;   
        timestamp.ulLo = timestamp.ulLo + top; 
        return (PRUint32)timestamp.ulLo;
    } else {
        ULONG msCount = -1;
        DosQuerySysInfo(QSV_MS_COUNT, QSV_MS_COUNT, &msCount, sizeof(msCount));
        return msCount;
    }
}

PRIntervalTime
_PR_MD_INTERVAL_PER_SEC()
{
    if (useHighResTimer) {
        return _os2_ticksPerSec;
    } else {
        return 1000;
    }
}