1 files changed, 31 insertions, 4 deletions

diff --git a/src/tsc.c b/src/tsc.c
index 64fe1b1..8038c0e 100644
--- a/src/tsc.c
+++ b/src/tsc.c
@@ -21,19 +21,46 @@
 #include "sandglass_impl.h"
 #include "sandglass.h"
 #include <time.h>
+#include <unistd.h>
 
 /* Gets the number of clock ticks per second */
 double
 sandglass_tsc_resolution()
 {
-  static long tsc = 0;
-  struct timespec ts = { .tv_sec = 0, .tv_nsec = 100000000 };
+  static long tsc = 0, grains1, grains2;
+
+  int monotonic;
+  struct timespec ts;
 
   if (tsc == 0) {
+    monotonic = sysconf(_SC_MONOTONIC_CLOCK) > 0;
+    if (monotonic) {
+      if (clock_gettime(CLOCK_MONOTONIC, &ts) != 0)
+        return 0.0/0.0;
+    } else {
+      if (clock_gettime(CLOCK_REALTIME, &ts) != 0)
+        return 0.0/0.0;
+    }
     tsc = sandglass_get_tsc();
-    while (nanosleep(&ts, &ts) != 0);
+    grains1 = sandglass_timespec_grains(&ts);
+    grains2 = grains1;
+
+    while (((grains2 >= grains1) ? grains2 - grains1
+                                 : 2000000000L + (grains2 - grains1))
+           < 10000000L)
+    {
+      if (monotonic) {
+        if (clock_gettime(CLOCK_MONOTONIC, &ts) != 0)
+          return 0.0/0.0;
+      } else {
+        if (clock_gettime(CLOCK_REALTIME, &ts) != 0)
+          return 0.0/0.0;
+      }
+      grains2 = sandglass_timespec_grains(&ts);
+    }
+
     tsc = sandglass_get_tsc() - tsc;
   }
 
-  return tsc*10.0;
+  return tsc*1.0e9/(grains2 - grains1);
 }