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os2inrval.c
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00001 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
00002 /* ***** BEGIN LICENSE BLOCK *****
00003  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
00004  *
00005  * The contents of this file are subject to the Mozilla Public License Version
00006  * 1.1 (the "License"); you may not use this file except in compliance with
00007  * the License. You may obtain a copy of the License at
00008  * http://www.mozilla.org/MPL/
00009  *
00010  * Software distributed under the License is distributed on an "AS IS" basis,
00011  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
00012  * for the specific language governing rights and limitations under the
00013  * License.
00014  *
00015  * The Original Code is the Netscape Portable Runtime (NSPR).
00016  *
00017  * The Initial Developer of the Original Code is
00018  * Netscape Communications Corporation.
00019  * Portions created by the Initial Developer are Copyright (C) 1998-2000
00020  * the Initial Developer. All Rights Reserved.
00021  *
00022  * Contributor(s):
00023  *
00024  * Alternatively, the contents of this file may be used under the terms of
00025  * either the GNU General Public License Version 2 or later (the "GPL"), or
00026  * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
00027  * in which case the provisions of the GPL or the LGPL are applicable instead
00028  * of those above. If you wish to allow use of your version of this file only
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00036  * ***** END LICENSE BLOCK ***** */
00037 
00038 /*
00039  * OS/2 interval timers
00040  *
00041  */
00042 
00043 #include "primpl.h"
00044 
00045 static PRBool useHighResTimer = PR_FALSE;
00046 PRIntervalTime _os2_ticksPerSec = -1;
00047 PRIntn _os2_bitShift = 0;
00048 PRInt32 _os2_highMask = 0;
00049    
00050 void
00051 _PR_MD_INTERVAL_INIT()
00052 {
00053     char *envp;
00054     ULONG timerFreq;
00055     APIRET rc;
00056 
00057     if ((envp = getenv("NSPR_OS2_NO_HIRES_TIMER")) != NULL) {
00058         if (atoi(envp) == 1)
00059            return;
00060     }
00061 
00062     timerFreq = 0; /* OS/2 high-resolution timer frequency in Hz */
00063     rc = DosTmrQueryFreq(&timerFreq);
00064     if (NO_ERROR == rc) {
00065         useHighResTimer = PR_TRUE;
00066         PR_ASSERT(timerFreq != 0);
00067         while (timerFreq > PR_INTERVAL_MAX) {
00068             timerFreq >>= 1;
00069             _os2_bitShift++;
00070             _os2_highMask = (_os2_highMask << 1)+1;
00071         }
00072 
00073         _os2_ticksPerSec = timerFreq;
00074         PR_ASSERT(_os2_ticksPerSec > PR_INTERVAL_MIN);
00075     }
00076 }
00077 
00078 PRIntervalTime
00079 _PR_MD_GET_INTERVAL()
00080 {
00081     if (useHighResTimer) {
00082         QWORD timestamp;
00083         PRInt32 top;
00084         APIRET rc = DosTmrQueryTime(&timestamp);
00085         if (NO_ERROR != rc) {
00086             return -1;
00087         }
00088         /* Sadly, nspr requires the interval to range from 1000 ticks per
00089          * second to only 100000 ticks per second. DosTmrQueryTime is too
00090          * high resolution...
00091          */
00092         top = timestamp.ulHi & _os2_highMask;
00093         top = top << (32 - _os2_bitShift);
00094         timestamp.ulLo = timestamp.ulLo >> _os2_bitShift;   
00095         timestamp.ulLo = timestamp.ulLo + top; 
00096         return (PRUint32)timestamp.ulLo;
00097     } else {
00098         ULONG msCount = -1;
00099         DosQuerySysInfo(QSV_MS_COUNT, QSV_MS_COUNT, &msCount, sizeof(msCount));
00100         return msCount;
00101     }
00102 }
00103 
00104 PRIntervalTime
00105 _PR_MD_INTERVAL_PER_SEC()
00106 {
00107     if (useHighResTimer) {
00108         return _os2_ticksPerSec;
00109     } else {
00110         return 1000;
00111     }
00112 }