initial cleanup and mapping

examples/delayTest.c

@@ -0,0 +1,107 @@
+/*
+ * 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 <sys/time.h>
+
+#define	CYCLES	1000
+
+int main()
+{
+  int x ;
+  struct timeval t1, t2 ;
+  int t ;
+  int max, min ;
+  int del ;
+  int underRuns, overRuns, exactRuns, total ;
+  int descheds ;
+
+  if (wiringPiSetup () == -1)
+    return 1 ;
+
+  piHiPri (10) ; sleep (1) ;
+
+// Baseline test
+
+  gettimeofday (&t1, NULL) ;
+  gettimeofday (&t2, NULL) ;
+
+  t = t2.tv_usec - t1.tv_usec ;
+  printf ("Baseline test: %d\n", t);
+
+  for (del = 1 ; del < 200 ; ++del)
+  {
+    underRuns = overRuns = exactRuns = total = 0 ;
+    descheds = 0 ;
+    max = del ;
+    min = del ;
+
+    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) ;
+
+	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) ;
+  }
+
+  return 0 ;
+}