add linkly and unlikely optimisation to ltt_time_compare

[lttv.git] / ltt / branches / poly / ltt / time.h

diff --git a/ltt/branches/poly/ltt/time.h b/ltt/branches/poly/ltt/time.h
index db85c69c7dc6ccda5ef508502ba66afeacf90f83..a257018275262b2dd2da7b87a5fc1e1598492a02 100644 (file)
--- a/ltt/branches/poly/ltt/time.h
+++ b/ltt/branches/poly/ltt/time.h
@@ -29,6 +29,7 @@ typedef struct _LttTime {
 
 
 #define NANOSECONDS_PER_SECOND 1000000000
+#define SHIFT_CONST 1.07374182400631629848
 
 static const LttTime ltt_time_zero = { 0, 0 };
 
@@ -61,14 +62,19 @@ static inline LttTime ltt_time_add(LttTime t1, LttTime t2)
   return res;
 }
 
+#define likely(x) __builtin_expect(!!(x), 1)
+#define unlikely(x) __builtin_expect(!!(x), 0)
 
+/* Fastest comparison : t1 > t2 */
 static inline int ltt_time_compare(LttTime t1, LttTime t2)
 {
-  if(t1.tv_sec > t2.tv_sec) return 1;
-  if(t1.tv_sec < t2.tv_sec) return -1;
-  if(t1.tv_nsec > t2.tv_nsec) return 1;
-  if(t1.tv_nsec < t2.tv_nsec) return -1;
-  return 0;
+  int ret=0;
+  if(likely(t1.tv_sec > t2.tv_sec)) ret = 1;
+  else if(unlikely(t1.tv_sec < t2.tv_sec)) ret = -1;
+  else if(likely(t1.tv_nsec > t2.tv_nsec)) ret = 1;
+  else if(unlikely(t1.tv_nsec < t2.tv_nsec)) ret = -1;
+  
+  return ret;
 }
 
 #define LTT_TIME_MIN(a,b) ((ltt_time_compare((a),(b)) < 0) ? (a) : (b))
@@ -110,7 +116,8 @@ static inline LttTime ltt_time_from_double(double t1)
     g_warning("Conversion from non precise double to LttTime");
 #endif //EXTRA_CHECK
   LttTime res;
-  res.tv_sec = t1/(double)NANOSECONDS_PER_SECOND;
+  //res.tv_sec = t1/(double)NANOSECONDS_PER_SECOND;
+  res.tv_sec = (guint64)(t1 * SHIFT_CONST) >> 30;
   res.tv_nsec = (t1 - (res.tv_sec*NANOSECONDS_PER_SECOND));
   return res;
 }