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102 lines
2.5 KiB
102 lines
2.5 KiB
/* |
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* delayTest.c: |
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* Just a little test program I'm using to experiment with |
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* various timings and latency, etc. |
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* |
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* Copyright (c) 2012-2013 Gordon Henderson. <projects@drogon.net> |
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*********************************************************************** |
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* This file is part of wiringPi: |
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* https://projects.drogon.net/raspberry-pi/wiringpi/ |
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* |
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* wiringPi is free software: you can redistribute it and/or modify |
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* it under the terms of the GNU Lesser 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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* |
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* wiringPi 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 Lesser General Public License for more details. |
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* |
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* You should have received a copy of the GNU Lesser General Public License |
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* along with wiringPi. If not, see <http://www.gnu.org/licenses/>. |
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*********************************************************************** |
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*/ |
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#include <stdio.h> |
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#include <unistd.h> |
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#include <sys/time.h> |
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#define CYCLES 1000 |
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int main() |
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{ |
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int x ; |
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struct timeval t1, t2, t3 ; |
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int t ; |
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int max, min ; |
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int del ; |
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int underRuns, overRuns, exactRuns, bogusRuns, total ; |
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int descheds ; |
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// Baseline test |
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gettimeofday (&t1, NULL) ; |
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gettimeofday (&t2, NULL) ; |
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t = t2.tv_usec - t1.tv_usec ; |
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printf ("Baseline test: %d\n", t); |
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for (del = 1 ; del < 200 ; ++del) |
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{ |
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underRuns = overRuns = exactRuns = total = 0 ; |
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descheds = 0 ; |
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max = 0 ; |
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min = 999 ; |
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for (x = 0 ; x < CYCLES ; ++x) |
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{ |
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for (;;) // Repeat this if we get a delay over 999uS |
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{ // -> High probability Linux has deschedulled us |
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gettimeofday (&t1, NULL) ; |
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usleep (del) ; |
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// delayMicroseconds (del) ; |
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gettimeofday (&t2, NULL) ; |
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timersub (&t2, &t1, &t3) ; |
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t = t3.tv_usec ; |
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if (t > 999) |
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{ |
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++descheds ; |
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continue ; |
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} |
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else |
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break ; |
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} |
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if (t == del) |
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++exactRuns ; |
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else if (t < del) |
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++underRuns ; |
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else if (t > del) |
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++overRuns ; |
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if (t > max) |
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max = t ; |
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else if (t < min) |
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min = t ; |
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total += t ; |
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} |
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printf ("Delay: %3d. Min: %3d, Max: %3d, Unders: %3d, Overs: %3d, Exacts: %3d, Average: %3d, Descheds: %2d\n", |
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del, min, max, underRuns, overRuns, exactRuns, total / CYCLES, descheds) ; |
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fflush (stdout) ; |
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usleep (1000) ; |
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} |
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return 0 ; |
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}
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