lttv/lttv/time.h

   1 /* This file is part of the Linux Trace Toolkit trace reading library
   2  * Copyright (C) 2003-2004 Michel Dagenais
   3  *               2005 Mathieu Desnoyers
   4  *
   5  * This library is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU Lesser General Public
   7  * License Version 2.1 as published by the Free Software Foundation.
   8  *
   9  * This library is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * Lesser General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Lesser General Public
  15  * License along with this library; if not, write to the
  16  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17  * Boston, MA 02111-1307, USA.
  18  */
  19
  20 #ifndef LTT_TIME_H
  21 #define LTT_TIME_H
  22
  23 #include <glib.h>
  24 #include <math.h>
  25 #include <lttv/compiler.h>
  26
  27 typedef struct _LttTime {
  28   unsigned long tv_sec;
  29   unsigned long tv_nsec;
  30 } LttTime;
  31
  32
  33 #define NANOSECONDS_PER_SECOND 1000000000
  34
  35 /* We give the DIV and MUL constants so we can always multiply, for a
  36  * division as well as a multiplication of NANOSECONDS_PER_SECOND */
  37 /* 2^30/1.07374182400631629848 = 1000000000.0 */
  38 #define DOUBLE_SHIFT_CONST_DIV 1.07374182400631629848
  39 #define DOUBLE_SHIFT 30
  40
  41 /* 2^30*0.93132257461547851562 = 1000000000.0000000000 */
  42 #define DOUBLE_SHIFT_CONST_MUL 0.93132257461547851562
  43
  44
  45 /* 1953125 * 2^9 = NANOSECONDS_PER_SECOND */
  46 #define LTT_TIME_UINT_SHIFT_CONST 1953125
  47 #define LTT_TIME_UINT_SHIFT 9
  48
  49
  50 static const LttTime ltt_time_zero = { 0, 0 };
  51
  52 static const LttTime ltt_time_one = { 0, 1 };
  53
  54 static const LttTime ltt_time_infinite = { G_MAXUINT, NANOSECONDS_PER_SECOND };
  55
  56 static inline LttTime ltt_time_sub(LttTime t1, LttTime t2)
  57 {
  58   LttTime res;
  59   res.tv_sec  = t1.tv_sec  - t2.tv_sec;
  60   res.tv_nsec = t1.tv_nsec - t2.tv_nsec;
  61   /* unlikely : given equal chance to be anywhere in t1.tv_nsec, and
  62    * higher probability of low value for t2.tv_sec, we will habitually
  63    * not wrap.
  64    */
  65   if(unlikely(t1.tv_nsec < t2.tv_nsec)) {
  66     res.tv_sec--;
  67     res.tv_nsec += NANOSECONDS_PER_SECOND;
  68   }
  69   return res;
  70 }
  71
  72
  73 static inline LttTime ltt_time_add(LttTime t1, LttTime t2)
  74 {
  75   LttTime res;
  76   res.tv_nsec = t1.tv_nsec + t2.tv_nsec;
  77   res.tv_sec = t1.tv_sec + t2.tv_sec;
  78   /* unlikely : given equal chance to be anywhere in t1.tv_nsec, and
  79    * higher probability of low value for t2.tv_sec, we will habitually
  80    * not wrap.
  81    */
  82   if(unlikely(res.tv_nsec >= NANOSECONDS_PER_SECOND)) {
  83     res.tv_sec++;
  84     res.tv_nsec -= NANOSECONDS_PER_SECOND;
  85   }
  86   return res;
  87 }
  88
  89 /* Fastest comparison : t1 > t2 */
  90 static inline int ltt_time_compare(LttTime t1, LttTime t2)
  91 {
  92   int ret=0;
  93   if(likely(t1.tv_sec > t2.tv_sec)) ret = 1;
  94   else if(unlikely(t1.tv_sec < t2.tv_sec)) ret = -1;
  95   else if(likely(t1.tv_nsec > t2.tv_nsec)) ret = 1;
  96   else if(unlikely(t1.tv_nsec < t2.tv_nsec)) ret = -1;
  97
  98   return ret;
  99 }
 100
 101 #define LTT_TIME_MIN(a,b) ((ltt_time_compare((a),(b)) < 0) ? (a) : (b))
 102 #define LTT_TIME_MAX(a,b) ((ltt_time_compare((a),(b)) > 0) ? (a) : (b))
 103
 104 #define MAX_TV_SEC_TO_DOUBLE 0x7FFFFF
 105 static inline double ltt_time_to_double(LttTime t1)
 106 {
 107   /* We lose precision if tv_sec is > than (2^23)-1
 108    *
 109    * Max values that fits in a double (53 bits precision on normalised
 110    * mantissa):
 111    * tv_nsec : NANOSECONDS_PER_SECONDS : 2^30
 112    *
 113    * So we have 53-30 = 23 bits left for tv_sec.
 114    * */
 115 #ifdef EXTRA_CHECK
 116   g_assert(t1.tv_sec <= MAX_TV_SEC_TO_DOUBLE);
 117   if(t1.tv_sec > MAX_TV_SEC_TO_DOUBLE)
 118     g_warning("Precision loss in conversion LttTime to double");
 119 #endif //EXTRA_CHECK
 120   return ((double)((guint64)t1.tv_sec<<DOUBLE_SHIFT)
 121                   * (double)DOUBLE_SHIFT_CONST_MUL)
 122                   + (double)t1.tv_nsec;
 123 }
 124
 125
 126 static inline LttTime ltt_time_from_double(double t1)
 127 {
 128   /* We lose precision if tv_sec is > than (2^23)-1
 129    *
 130    * Max values that fits in a double (53 bits precision on normalised
 131    * mantissa):
 132    * tv_nsec : NANOSECONDS_PER_SECONDS : 2^30
 133    *
 134    * So we have 53-30 = 23 bits left for tv_sec.
 135    * */
 136 #ifdef EXTRA_CHECK
 137   g_assert(t1 <= MAX_TV_SEC_TO_DOUBLE);
 138   if(t1 > MAX_TV_SEC_TO_DOUBLE)
 139     g_warning("Conversion from non precise double to LttTime");
 140 #endif //EXTRA_CHECK
 141   LttTime res;
 142   //res.tv_sec = t1/(double)NANOSECONDS_PER_SECOND;
 143   res.tv_sec = (guint64)(t1 * DOUBLE_SHIFT_CONST_DIV) >> DOUBLE_SHIFT;
 144   res.tv_nsec = (t1 - (((guint64)res.tv_sec<<LTT_TIME_UINT_SHIFT))
 145                                * LTT_TIME_UINT_SHIFT_CONST);
 146   return res;
 147 }
 148
 149 /* Use ltt_time_to_double and ltt_time_from_double to check for lack
 150  * of precision.
 151  */
 152 static inline LttTime ltt_time_mul(LttTime t1, double d)
 153 {
 154   LttTime res;
 155
 156   double time_double = ltt_time_to_double(t1);
 157
 158   time_double = time_double * d;
 159
 160   res = ltt_time_from_double(time_double);
 161
 162   return res;
 163
 164 #if 0
 165   /* What is that ? (Mathieu) */
 166   if(f == 0.0){
 167     res.tv_sec = 0;
 168     res.tv_nsec = 0;
 169   }else{
 170   double d;
 171     d = 1.0/f;
 172     sec = t1.tv_sec / (double)d;
 173     res.tv_sec = sec;
 174     res.tv_nsec = t1.tv_nsec / (double)d + (sec - res.tv_sec) *
 175                   NANOSECONDS_PER_SECOND;
 176     res.tv_sec += res.tv_nsec / NANOSECONDS_PER_SECOND;
 177     res.tv_nsec %= NANOSECONDS_PER_SECOND;
 178   }
 179   return res;
 180 #endif //0
 181 }
 182
 183
 184 /* Use ltt_time_to_double and ltt_time_from_double to check for lack
 185  * of precision.
 186  */
 187 static inline LttTime ltt_time_div(LttTime t1, double d)
 188 {
 189   LttTime res;
 190
 191   double time_double = ltt_time_to_double(t1);
 192
 193   time_double = time_double / d;
 194
 195   res = ltt_time_from_double(time_double);
 196
 197   return res;
 198
 199
 200 #if 0
 201   double sec;
 202   LttTime res;
 203
 204   sec = t1.tv_sec / (double)f;
 205   res.tv_sec = sec;
 206   res.tv_nsec = t1.tv_nsec / (double)f + (sec - res.tv_sec) *
 207       NANOSECONDS_PER_SECOND;
 208   res.tv_sec += res.tv_nsec / NANOSECONDS_PER_SECOND;
 209   res.tv_nsec %= NANOSECONDS_PER_SECOND;
 210   return res;
 211 #endif //0
 212 }
 213
 214
 215 static inline guint64 ltt_time_to_uint64(LttTime t1)
 216 {
 217   return (((guint64)t1.tv_sec*LTT_TIME_UINT_SHIFT_CONST) << LTT_TIME_UINT_SHIFT)
 218                        + (guint64)t1.tv_nsec;
 219 }
 220
 221
 222 #define MAX_TV_SEC_TO_UINT64 0x3FFFFFFFFFFFFFFFULL
 223
 224 /* The likely branch is with sec != 0, because most events in a bloc
 225  * will be over 1s from the block start. (see tracefile.c)
 226  */
 227 static inline LttTime ltt_time_from_uint64(guint64 t1)
 228 {
 229   /* We lose precision if tv_sec is > than (2^62)-1
 230    * */
 231 #ifdef EXTRA_CHECK
 232   g_assert(t1 <= MAX_TV_SEC_TO_UINT64);
 233   if(t1 > MAX_TV_SEC_TO_UINT64)
 234     g_warning("Conversion from uint64 to non precise LttTime");
 235 #endif //EXTRA_CHECK
 236   LttTime res;
 237   //if(unlikely(t1 >= NANOSECONDS_PER_SECOND)) {
 238   if(likely(t1>>LTT_TIME_UINT_SHIFT >= LTT_TIME_UINT_SHIFT_CONST)) {
 239     //res.tv_sec = t1/NANOSECONDS_PER_SECOND;
 240     res.tv_sec = (t1>>LTT_TIME_UINT_SHIFT)
 241                          /LTT_TIME_UINT_SHIFT_CONST; // acceleration
 242     res.tv_nsec = (t1 - res.tv_sec*NANOSECONDS_PER_SECOND);
 243   } else {
 244     res.tv_sec = 0;
 245     res.tv_nsec = (guint32)t1;
 246   }
 247   return res;
 248 }
 249
 250 #endif // LTT_TIME_H