Quite a few changes here.

[wiringPi.git] / examples / delayTest.c

diff --git a/examples/delayTest.c b/examples/delayTest.c
index 8c955224ecb08ef78c61edb57182492ee892b93d..4c8b6ca40495b362be10241364bef35f186c9d98 100644 (file)
--- a/examples/delayTest.c
+++ b/examples/delayTest.c
@@ -1,32 +1,50 @@
+/*
+ * delayTest.c:
+ *     Just a little test program I'm using to experiment with
+ *     various timings and latency, etc.
+ *
+ * Copyright (c) 2012-2013 Gordon Henderson. <projects@drogon.net>
+ ***********************************************************************
+ * This file is part of wiringPi:
+ *     https://projects.drogon.net/raspberry-pi/wiringpi/
+ *
+ *    wiringPi is free software: you can redistribute it and/or modify
+ *    it under the terms of the GNU Lesser General Public License as published by
+ *    the Free Software Foundation, either version 3 of the License, or
+ *    (at your option) any later version.
+ *
+ *    wiringPi is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU Lesser General Public License for more details.
+ *
+ *    You should have received a copy of the GNU Lesser General Public License
+ *    along with wiringPi.  If not, see <http://www.gnu.org/licenses/>.
+ ***********************************************************************
+ */
 
 #include <stdio.h>
 #include <unistd.h>
 #include <wiringPi.h>
 
-#include <time.h>
-#include <sys/types.h>
 #include <sys/time.h>
 
 #define        CYCLES  1000
-#define        DELAY   99
 
 int main()
 {
   int x ;
   struct timeval t1, t2 ;
-  long long    t ;
-  unsigned int max, min ;
-
-  unsigned int values [CYCLES] ;
-
-  max = 0 ;
-  min = 1000000 ;
+  int t ;
+  int max, min ;
+  int del ;
+  int underRuns, overRuns, exactRuns, total ;
+  int descheds ;
 
   if (wiringPiSetup () == -1)
     return 1 ;
 
-  piHiPri (10) ;
-  sleep (1) ;
+  piHiPri (10) ; sleep (1) ;
 
 // Baseline test
 
@@ -34,35 +52,56 @@ int main()
   gettimeofday (&t2, NULL) ;
 
   t = t2.tv_usec - t1.tv_usec ;
-  printf ("Baseline test: %lld\n", t);
+  printf ("Baseline test: %d\n", t);
 
-  for (x = 0 ; x < CYCLES ; ++x)
+  for (del = 1 ; del < 200 ; ++del)
   {
-    gettimeofday (&t1, NULL) ;
-    delayMicroseconds (DELAY) ;
-    gettimeofday (&t2, NULL) ;
-      
-    t = t2.tv_usec - t1.tv_usec ;
-    if (t > max) max = t ;
-    if (t < min) min = t ;
-    values [x] = t ;
-  }
+    underRuns = overRuns = exactRuns = total = 0 ;
+    descheds = 0 ;
+    max = del ;
+    min = del ;
 
-  printf ("Done: Max: %d, min: %d\n", max, min) ;
+    for (x = 0 ; x < CYCLES ; ++x)
+    {
+      for (;;)                         // Repeat this if we get a delay over 999uS
+      {                                        // -> High probability Linux has deschedulled us
+       gettimeofday (&t1, NULL) ;
+         delayMicroseconds (del) ;
+       gettimeofday (&t2, NULL) ;
 
-  for (x = 0 ; x < CYCLES ; ++x)
-  {
-    printf ("%4d", values [x]) ;
-    if (values [x] > DELAY)
-      printf (".") ;
-    else if (values [x] < DELAY)
-      printf ("-") ;
-    else
-      printf (" ") ;
-    if (((x + 1) % 20) == 0)
-      printf ("\n") ;
+       if (t2.tv_usec < t1.tv_usec)    // Counter wrapped
+         t = (1000000 + t2.tv_usec) - t1.tv_usec;
+       else
+         t = t2.tv_usec - t1.tv_usec ;
+       if (t > 999)
+       {
+         ++descheds ;
+         continue ;
+       }
+       else
+         break ;
+      }
+
+      if (t > max)
+      {
+        max = t ;
+       ++overRuns ;
+      }
+      else if (t < min)
+      {
+       min = t ;
+       ++underRuns ;
+      }
+      else
+       ++exactRuns ;
+
+      total += t ;
+    }
+    printf ("Delay: %3d. Min: %3d, Max: %3d, Unders: %3d, Overs: %3d, Exacts: %3d, Average: %3d,  Descheds: %2d\n",
+       del, min, max, underRuns, overRuns, exactRuns, total / CYCLES,  descheds) ;
+    fflush (stdout) ;
+    delay (1) ;
   }
-  printf ("\n") ;
 
   return 0 ;
 }