X-Git-Url: https://git.lttng.org/?a=blobdiff_plain;f=ltt%2Fbranches%2Fpoly%2Fltt%2Ftime.h;h=6622decea9f9f9a7c4dd70689cb7b3f414321787;hb=0a2cbfbed386cdcc594561824a2e3d0596ade446;hp=a257018275262b2dd2da7b87a5fc1e1598492a02;hpb=887208b719ee99e75c44a9366671cf17c83186d0;p=lttv.git

diff --git a/ltt/branches/poly/ltt/time.h b/ltt/branches/poly/ltt/time.h
index a2570182..6622dece 100644
--- a/ltt/branches/poly/ltt/time.h
+++ b/ltt/branches/poly/ltt/time.h
@@ -20,7 +20,8 @@
 #define LTT_TIME_H
 
 #include <glib.h>
-
+#include <ltt/compiler.h>
+#include <math.h>
 
 typedef struct _LttTime {
   unsigned long tv_sec;
@@ -29,7 +30,21 @@ typedef struct _LttTime {
 
 
 #define NANOSECONDS_PER_SECOND 1000000000
-#define SHIFT_CONST 1.07374182400631629848
+
+/* We give the DIV and MUL constants so we can always multiply, for a
+ * division as well as a multiplication of NANOSECONDS_PER_SECOND */
+/* 2^30/1.07374182400631629848 = 1000000000.0 */ 
+#define DOUBLE_SHIFT_CONST_DIV 1.07374182400631629848
+#define DOUBLE_SHIFT 30
+
+/* 2^30*0.93132257461547851562 = 1000000000.0000000000 */ 
+#define DOUBLE_SHIFT_CONST_MUL 0.93132257461547851562
+
+
+/* 1953125 * 2^9 = NANOSECONDS_PER_SECOND */
+#define LTT_TIME_UINT_SHIFT_CONST 1953125
+#define LTT_TIME_UINT_SHIFT 9
+
 
 static const LttTime ltt_time_zero = { 0, 0 };
 
@@ -42,7 +57,11 @@ static inline LttTime ltt_time_sub(LttTime t1, LttTime t2)
   LttTime res;
   res.tv_sec  = t1.tv_sec  - t2.tv_sec;
   res.tv_nsec = t1.tv_nsec - t2.tv_nsec;
-  if(t1.tv_nsec < t2.tv_nsec) {
+  /* unlikely : given equal chance to be anywhere in t1.tv_nsec, and
+   * higher probability of low value for t2.tv_sec, we will habitually
+   * not wrap.
+   */
+  if(unlikely(t1.tv_nsec < t2.tv_nsec)) {
     res.tv_sec--;
     res.tv_nsec += NANOSECONDS_PER_SECOND;
   }
@@ -55,16 +74,17 @@ static inline LttTime ltt_time_add(LttTime t1, LttTime t2)
   LttTime res;
   res.tv_nsec = t1.tv_nsec + t2.tv_nsec;
   res.tv_sec = t1.tv_sec + t2.tv_sec;
-  if(res.tv_nsec >= NANOSECONDS_PER_SECOND) {
+  /* unlikely : given equal chance to be anywhere in t1.tv_nsec, and
+   * higher probability of low value for t2.tv_sec, we will habitually
+   * not wrap.
+   */
+  if(unlikely(res.tv_nsec >= NANOSECONDS_PER_SECOND)) {
     res.tv_sec++;
     res.tv_nsec -= NANOSECONDS_PER_SECOND;
   }
   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)
 {
@@ -96,7 +116,9 @@ static inline double ltt_time_to_double(LttTime t1)
   if(t1.tv_sec > MAX_TV_SEC_TO_DOUBLE)
     g_warning("Precision loss in conversion LttTime to double");
 #endif //EXTRA_CHECK
-  return ((double)t1.tv_sec * (double)NANOSECONDS_PER_SECOND) + (double)t1.tv_nsec;
+  return round(((double)((guint64)t1.tv_sec<<DOUBLE_SHIFT)
+                  * (double)DOUBLE_SHIFT_CONST_MUL)
+                  + (double)t1.tv_nsec);
 }
 
 
@@ -117,8 +139,9 @@ static inline LttTime ltt_time_from_double(double t1)
 #endif //EXTRA_CHECK
   LttTime res;
   //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));
+  res.tv_sec = (guint64)(t1 * DOUBLE_SHIFT_CONST_DIV) >> DOUBLE_SHIFT;
+  res.tv_nsec = (round(t1) - (((guint64)res.tv_sec<<LTT_TIME_UINT_SHIFT))
+                               * LTT_TIME_UINT_SHIFT_CONST);
   return res;
 }
 
@@ -187,14 +210,19 @@ static inline LttTime ltt_time_div(LttTime t1, double d)
 #endif //0
 }
 
+
 static inline guint64 ltt_time_to_uint64(LttTime t1)
 {
-  return (guint64)t1.tv_sec*NANOSECONDS_PER_SECOND
-            + (guint64)t1.tv_nsec;
+  return (guint64)((t1.tv_sec*LTT_TIME_UINT_SHIFT_CONST) >> LTT_TIME_UINT_SHIFT)
+                       + (guint64)t1.tv_nsec;
 }
 
 
 #define MAX_TV_SEC_TO_UINT64 0x3FFFFFFFFFFFFFFFULL
+
+/* The likely branch is with sec != 0, because most events in a bloc
+ * will be over 1s from the block start. (see tracefile.c)
+ */
 static inline LttTime ltt_time_from_uint64(guint64 t1)
 {
   /* We lose precision if tv_sec is > than (2^62)-1
@@ -202,11 +230,19 @@ static inline LttTime ltt_time_from_uint64(guint64 t1)
 #ifdef EXTRA_CHECK
   g_assert(t1 <= MAX_TV_SEC_TO_UINT64);
   if(t1 > MAX_TV_SEC_TO_UINT64)
-    g_warning("Conversion from non precise uint64 to LttTime");
+    g_warning("Conversion from uint64 to non precise LttTime");
 #endif //EXTRA_CHECK
   LttTime res;
-  res.tv_sec = t1/NANOSECONDS_PER_SECOND;
-  res.tv_nsec = (t1 - res.tv_sec*NANOSECONDS_PER_SECOND);
+  //if(unlikely(t1 >= NANOSECONDS_PER_SECOND)) {
+  if(likely(t1>>LTT_TIME_UINT_SHIFT >= LTT_TIME_UINT_SHIFT_CONST)) {
+    //res.tv_sec = t1/NANOSECONDS_PER_SECOND;
+    res.tv_sec = (t1>>LTT_TIME_UINT_SHIFT)
+                         /LTT_TIME_UINT_SHIFT_CONST; // acceleration
+    res.tv_nsec = (t1 - res.tv_sec*NANOSECONDS_PER_SECOND);
+  } else {
+    res.tv_sec = 0;
+    res.tv_nsec = (guint32)t1;
+  }
   return res;
 }