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[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 642328e9001d9ac0c5ad08e5a98e4a16748e432d..14c15d1d237c1d7d184033636750a510a63e8e16 100644 (file)
--- a/ltt/branches/poly/ltt/time.h
+++ b/ltt/branches/poly/ltt/time.h
@@ -1,5 +1,6 @@
 /* This file is part of the Linux Trace Toolkit trace reading library
  * Copyright (C) 2003-2004 Michel Dagenais
+ *               2005 Mathieu Desnoyers
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
@@ -20,7 +21,8 @@
 #define LTT_TIME_H
 
 #include <glib.h>
-
+#include <ltt/compiler.h>
+#include <math.h>
 
 typedef struct _LttTime {
   unsigned long tv_sec;
@@ -30,6 +32,21 @@ typedef struct _LttTime {
 
 #define NANOSECONDS_PER_SECOND 1000000000
 
+/* 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 };
 
 static const LttTime ltt_time_one = { 0, 1 };
@@ -41,7 +58,11 @@ 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;
   }
@@ -54,21 +75,27 @@ 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;
 }
 
-
+/* 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))
@@ -90,7 +117,9 @@ 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 * NANOSECONDS_PER_SECOND) + (double)t1.tv_nsec;
+  return ((double)((guint64)t1.tv_sec<<DOUBLE_SHIFT)
+                  * (double)DOUBLE_SHIFT_CONST_MUL)
+                  + (double)t1.tv_nsec;
 }
 
 
@@ -110,8 +139,10 @@ 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_nsec = (t1 - (res.tv_sec*NANOSECONDS_PER_SECOND));
+  //res.tv_sec = t1/(double)NANOSECONDS_PER_SECOND;
+  res.tv_sec = (guint64)(t1 * DOUBLE_SHIFT_CONST_DIV) >> DOUBLE_SHIFT;
+  res.tv_nsec = (t1 - (((guint64)res.tv_sec<<LTT_TIME_UINT_SHIFT))
+                               * LTT_TIME_UINT_SHIFT_CONST);
   return res;
 }
 
@@ -180,14 +211,19 @@ 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
@@ -195,11 +231,19 @@ 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;
 }