106 lines
3.3 KiB
C
106 lines
3.3 KiB
C
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/*
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===========================================================================
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Doom 3 GPL Source Code
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Copyright (C) 1999-2011 id Software LLC, a ZeniMax Media company.
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This file is part of the Doom 3 GPL Source Code (?Doom 3 Source Code?).
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Doom 3 Source Code is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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Doom 3 Source Code is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with Doom 3 Source Code. If not, see <http://www.gnu.org/licenses/>.
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In addition, the Doom 3 Source Code is also subject to certain additional terms. You should have received a copy of these additional terms immediately following the terms and conditions of the GNU General Public License which accompanied the Doom 3 Source Code. If not, please request a copy in writing from id Software at the address below.
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If you have questions concerning this license or the applicable additional terms, you may contact in writing id Software LLC, c/o ZeniMax Media Inc., Suite 120, Rockville, Maryland 20850 USA.
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===========================================================================
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*/
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#include <stdio.h>
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#include <sys/time.h>
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#include <sched.h>
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#include <errno.h>
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/*
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================
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Sys_Milliseconds
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================
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*/
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/* base time in seconds, that's our origin
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timeval:tv_sec is an int:
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assuming this wraps every 0x7fffffff - ~68 years since the Epoch (1970) - we're safe till 2038
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using unsigned long data type to work right with Sys_XTimeToSysTime */
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unsigned long sys_timeBase = 0;
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/* current time in ms, using sys_timeBase as origin
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NOTE: sys_timeBase*1000 + curtime -> ms since the Epoch
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0x7fffffff ms - ~24 days
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or is it 48 days? the specs say int, but maybe it's casted from unsigned int?
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*/
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int Sys_Milliseconds(void)
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{
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int curtime;
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struct timeval tp;
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gettimeofday(&tp, NULL);
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if (!sys_timeBase) {
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sys_timeBase = tp.tv_sec;
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return tp.tv_usec / 1000;
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}
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curtime = (tp.tv_sec - sys_timeBase) * 1000 + tp.tv_usec / 1000;
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return curtime;
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}
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#define STAT_BUF 100
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int main(int argc, void *argv[]) {
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int start = 30; // start waiting with 30 ms
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int dec = 2; // decrement by 2 ms
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int min = 4; // min wait test
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int i, j, now, next;
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int stats[STAT_BUF];
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struct sched_param parm;
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Sys_Milliseconds(); // init
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// set schedule policy to see if that affects usleep
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// (root rights required for that)
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parm.sched_priority = 99;
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if ( sched_setscheduler(0, SCHED_RR, &parm) != 0 ) {
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printf("sched_setscheduler SCHED_RR failed: %s\n", strerror(errno) );
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} else {
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printf("sched_setscheduler SCHED_RR ok\n");
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}
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// now run the test
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for( i = start ; i >= min ; i -= dec ) {
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printf( "sleep %d ms", i );
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for( j = 0 ; j < STAT_BUF ; j++ ) {
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now = Sys_Milliseconds();
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usleep(i*1000);
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stats[j] = Sys_Milliseconds() - now;
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}
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for( j = 0; j < STAT_BUF; j++) {
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if ( ! (j & 0xf) ) {
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printf("\n");
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}
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printf( "%d ", stats[j] );
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}
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printf("\n");
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}
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return 0;
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}
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