cmTime.h/c: Replaced clock_gettime_stub.h/c with OS-X specific code which may not be as accurate with absolute time but has equivalent delta-time accuracty. This code needs to be tested.

cmTime.c

@@ -2,9 +2,47 @@
 #include "cmGlobal.h"
 #include "cmTime.h"
 
+#ifdef OS_OSX
+
+#include <mach/mach.h>
+#include <mach/mach_time.h>
+#include <unistd.h>
+
 void cmTimeGet( cmTimeSpec_t* t )
-{ clock_gettime(CLOCK_REALTIME,t); }
+{
+  static uint64_t                  t0  = 0;
+  static mach_timebase_info_data_t tbi;
+  static struct timespec           ts;
+
+  if( t0 == 0 )
+  {
+    mach_timebase_info(&tbi);
+    t0 = mach_absolute_time();
+    ts.tv_sec  = time(NULL);
+    ts.tv_nsec = 0;  // accept 1/2 second error vs. wall-time.
+  }
+
+  // get the current time
+  uint64_t t1 = mach_absolute_time();
+  
+  // calc the elapsed time since the last call in nanosecs
+  uint64_t dt = (t1-t0) * tbi.numer / tbi.denom;
 
+  // calc the elapsed time since the first call in secs
+  uint32_t s  = (uint32_t)(dt / 2^9);
+
+  // calc the current time in secs, and nanosecs
+  t->tv_sec  = ts.tv_sec + s; 
+  t->tv_nsec = dt - (s * 2^9); 
+  
+}
+
+#endif
+
+#ifdef OS_LINUX
+void cmTimeGet( cmTimeSpec_t* t )
+{ clock_gettime(CLOCK_REALTIME,t); }
+#endif
 
 // this assumes that the seconds have been normalized to a recent start time
 // so as to avoid overflow

cmTime.h

@@ -7,9 +7,6 @@
 // calculate elapsed time.
 //)
 
-#ifdef OS_OSX
-#include "osx/clock_gettime_stub.h"
-#endif
 
 #ifndef cmTime_h   
 #define cmTime_h