3 * Just a little test program I'm using to experiment with
4 * various timings and latency, etc.
6 * Copyright (c) 2012-2013 Gordon Henderson. <projects@drogon.net>
7 ***********************************************************************
8 * This file is part of wiringPi:
9 * https://projects.drogon.net/raspberry-pi/wiringpi/
11 * wiringPi is free software: you can redistribute it and/or modify
12 * it under the terms of the GNU Lesser General Public License as published by
13 * the Free Software Foundation, either version 3 of the License, or
14 * (at your option) any later version.
16 * wiringPi is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 * GNU Lesser General Public License for more details.
21 * You should have received a copy of the GNU Lesser General Public License
22 * along with wiringPi. If not, see <http://www.gnu.org/licenses/>.
23 ***********************************************************************
37 struct timeval t1, t2 ;
41 int underRuns, overRuns, exactRuns, total ;
44 if (wiringPiSetup () == -1)
47 piHiPri (10) ; sleep (1) ;
51 gettimeofday (&t1, NULL) ;
52 gettimeofday (&t2, NULL) ;
54 t = t2.tv_usec - t1.tv_usec ;
55 printf ("Baseline test: %d\n", t);
57 for (del = 1 ; del < 200 ; ++del)
59 underRuns = overRuns = exactRuns = total = 0 ;
64 for (x = 0 ; x < CYCLES ; ++x)
66 for (;;) // Repeat this if we get a delay over 999uS
67 { // -> High probability Linux has deschedulled us
68 gettimeofday (&t1, NULL) ;
69 delayMicroseconds (del) ;
70 gettimeofday (&t2, NULL) ;
72 if (t2.tv_usec < t1.tv_usec) // Counter wrapped
73 t = (1000000 + t2.tv_usec) - t1.tv_usec;
75 t = t2.tv_usec - t1.tv_usec ;
100 printf ("Delay: %3d. Min: %3d, Max: %3d, Unders: %3d, Overs: %3d, Exacts: %3d, Average: %3d, Descheds: %2d\n",
101 del, min, max, underRuns, overRuns, exactRuns, total / CYCLES, descheds) ;