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 typedef struct _TimeInterval {
  33   LttTime start_time;
  34   LttTime end_time;
  35 } TimeInterval;
  36
  37 #define NANOSECONDS_PER_SECOND 1000000000
  38
  39 /* We give the DIV and MUL constants so we can always multiply, for a
  40  * division as well as a multiplication of NANOSECONDS_PER_SECOND */
  41 /* 2^30/1.07374182400631629848 = 1000000000.0 */
  42 #define DOUBLE_SHIFT_CONST_DIV 1.07374182400631629848
  43 #define DOUBLE_SHIFT 30
  44
  45 /* 2^30*0.93132257461547851562 = 1000000000.0000000000 */
  46 #define DOUBLE_SHIFT_CONST_MUL 0.93132257461547851562
  47
  48
  49 /* 1953125 * 2^9 = NANOSECONDS_PER_SECOND */
  50 #define LTT_TIME_UINT_SHIFT_CONST 1953125
  51 #define LTT_TIME_UINT_SHIFT 9
  52
  53
  54 static const LttTime ltt_time_zero = { 0, 0 };
  55
  56 static const LttTime ltt_time_one = { 0, 1 };
  57
  58 static const LttTime ltt_time_infinite = { G_MAXUINT, NANOSECONDS_PER_SECOND };
  59
  60 static inline LttTime ltt_time_sub(LttTime t1, LttTime t2)
  61 {
  62   LttTime res;
  63   res.tv_sec  = t1.tv_sec  - t2.tv_sec;
  64   res.tv_nsec = t1.tv_nsec - t2.tv_nsec;
  65   /* unlikely : given equal chance to be anywhere in t1.tv_nsec, and
  66    * higher probability of low value for t2.tv_sec, we will habitually
  67    * not wrap.
  68    */
  69   if(unlikely(t1.tv_nsec < t2.tv_nsec)) {
  70     res.tv_sec--;
  71     res.tv_nsec += NANOSECONDS_PER_SECOND;
  72   }
  73   return res;
  74 }
  75
  76
  77 static inline LttTime ltt_time_add(LttTime t1, LttTime t2)
  78 {
  79   LttTime res;
  80   res.tv_nsec = t1.tv_nsec + t2.tv_nsec;
  81   res.tv_sec = t1.tv_sec + t2.tv_sec;
  82   /* unlikely : given equal chance to be anywhere in t1.tv_nsec, and
  83    * higher probability of low value for t2.tv_sec, we will habitually
  84    * not wrap.
  85    */
  86   if(unlikely(res.tv_nsec >= NANOSECONDS_PER_SECOND)) {
  87     res.tv_sec++;
  88     res.tv_nsec -= NANOSECONDS_PER_SECOND;
  89   }
  90   return res;
  91 }
  92
  93 /* Fastest comparison : t1 > t2 */
  94 static inline int ltt_time_compare(LttTime t1, LttTime t2)
  95 {
  96   int ret=0;
  97   if(likely(t1.tv_sec > t2.tv_sec)) ret = 1;
  98   else if(unlikely(t1.tv_sec < t2.tv_sec)) ret = -1;
  99   else if(likely(t1.tv_nsec > t2.tv_nsec)) ret = 1;
 100   else if(unlikely(t1.tv_nsec < t2.tv_nsec)) ret = -1;
 101
 102   return ret;
 103 }
 104
 105 #define LTT_TIME_MIN(a,b) ((ltt_time_compare((a),(b)) < 0) ? (a) : (b))
 106 #define LTT_TIME_MAX(a,b) ((ltt_time_compare((a),(b)) > 0) ? (a) : (b))
 107
 108 #define MAX_TV_SEC_TO_DOUBLE 0x7FFFFF
 109 static inline double ltt_time_to_double(LttTime t1)
 110 {
 111   /* We lose precision if tv_sec is > than (2^23)-1
 112    *
 113    * Max values that fits in a double (53 bits precision on normalised
 114    * mantissa):
 115    * tv_nsec : NANOSECONDS_PER_SECONDS : 2^30
 116    *
 117    * So we have 53-30 = 23 bits left for tv_sec.
 118    * */
 119 #ifdef EXTRA_CHECK
 120   g_assert(t1.tv_sec <= MAX_TV_SEC_TO_DOUBLE);
 121   if(t1.tv_sec > MAX_TV_SEC_TO_DOUBLE)
 122     g_warning("Precision loss in conversion LttTime to double");
 123 #endif //EXTRA_CHECK
 124   return ((double)((guint64)t1.tv_sec<<DOUBLE_SHIFT)
 125                   * (double)DOUBLE_SHIFT_CONST_MUL)
 126                   + (double)t1.tv_nsec;
 127 }
 128
 129
 130 static inline LttTime ltt_time_from_double(double t1)
 131 {
 132   /* We lose precision if tv_sec is > than (2^23)-1
 133    *
 134    * Max values that fits in a double (53 bits precision on normalised
 135    * mantissa):
 136    * tv_nsec : NANOSECONDS_PER_SECONDS : 2^30
 137    *
 138    * So we have 53-30 = 23 bits left for tv_sec.
 139    * */
 140 #ifdef EXTRA_CHECK
 141   g_assert(t1 <= MAX_TV_SEC_TO_DOUBLE);
 142   if(t1 > MAX_TV_SEC_TO_DOUBLE)
 143     g_warning("Conversion from non precise double to LttTime");
 144 #endif //EXTRA_CHECK
 145   LttTime res;
 146   //res.tv_sec = t1/(double)NANOSECONDS_PER_SECOND;
 147   res.tv_sec = (guint64)(t1 * DOUBLE_SHIFT_CONST_DIV) >> DOUBLE_SHIFT;
 148   res.tv_nsec = (t1 - (((guint64)res.tv_sec<<LTT_TIME_UINT_SHIFT))
 149                                * LTT_TIME_UINT_SHIFT_CONST);
 150   return res;
 151 }
 152
 153 /* Use ltt_time_to_double and ltt_time_from_double to check for lack
 154  * of precision.
 155  */
 156 static inline LttTime ltt_time_mul(LttTime t1, double d)
 157 {
 158   LttTime res;
 159
 160   double time_double = ltt_time_to_double(t1);
 161
 162   time_double = time_double * d;
 163
 164   res = ltt_time_from_double(time_double);
 165
 166   return res;
 167
 168 #if 0
 169   /* What is that ? (Mathieu) */
 170   if(f == 0.0){
 171     res.tv_sec = 0;
 172     res.tv_nsec = 0;
 173   }else{
 174   double d;
 175     d = 1.0/f;
 176     sec = t1.tv_sec / (double)d;
 177     res.tv_sec = sec;
 178     res.tv_nsec = t1.tv_nsec / (double)d + (sec - res.tv_sec) *
 179                   NANOSECONDS_PER_SECOND;
 180     res.tv_sec += res.tv_nsec / NANOSECONDS_PER_SECOND;
 181     res.tv_nsec %= NANOSECONDS_PER_SECOND;
 182   }
 183   return res;
 184 #endif //0
 185 }
 186
 187
 188 /* Use ltt_time_to_double and ltt_time_from_double to check for lack
 189  * of precision.
 190  */
 191 static inline LttTime ltt_time_div(LttTime t1, double d)
 192 {
 193   LttTime res;
 194
 195   double time_double = ltt_time_to_double(t1);
 196
 197   time_double = time_double / d;
 198
 199   res = ltt_time_from_double(time_double);
 200
 201   return res;
 202
 203
 204 #if 0
 205   double sec;
 206   LttTime res;
 207
 208   sec = t1.tv_sec / (double)f;
 209   res.tv_sec = sec;
 210   res.tv_nsec = t1.tv_nsec / (double)f + (sec - res.tv_sec) *
 211       NANOSECONDS_PER_SECOND;
 212   res.tv_sec += res.tv_nsec / NANOSECONDS_PER_SECOND;
 213   res.tv_nsec %= NANOSECONDS_PER_SECOND;
 214   return res;
 215 #endif //0
 216 }
 217
 218
 219 static inline guint64 ltt_time_to_uint64(LttTime t1)
 220 {
 221   return (((guint64)t1.tv_sec*LTT_TIME_UINT_SHIFT_CONST) << LTT_TIME_UINT_SHIFT)
 222                        + (guint64)t1.tv_nsec;
 223 }
 224
 225
 226 #define MAX_TV_SEC_TO_UINT64 0x3FFFFFFFFFFFFFFFULL
 227
 228 /* The likely branch is with sec != 0, because most events in a bloc
 229  * will be over 1s from the block start. (see tracefile.c)
 230  */
 231 static inline LttTime ltt_time_from_uint64(guint64 t1)
 232 {
 233   /* We lose precision if tv_sec is > than (2^62)-1
 234    * */
 235 #ifdef EXTRA_CHECK
 236   g_assert(t1 <= MAX_TV_SEC_TO_UINT64);
 237   if(t1 > MAX_TV_SEC_TO_UINT64)
 238     g_warning("Conversion from uint64 to non precise LttTime");
 239 #endif //EXTRA_CHECK
 240   LttTime res;
 241   //if(unlikely(t1 >= NANOSECONDS_PER_SECOND)) {
 242   if(likely(t1>>LTT_TIME_UINT_SHIFT >= LTT_TIME_UINT_SHIFT_CONST)) {
 243     //res.tv_sec = t1/NANOSECONDS_PER_SECOND;
 244     res.tv_sec = (t1>>LTT_TIME_UINT_SHIFT)
 245                          /LTT_TIME_UINT_SHIFT_CONST; // acceleration
 246     res.tv_nsec = (t1 - res.tv_sec*NANOSECONDS_PER_SECOND);
 247   } else {
 248     res.tv_sec = 0;
 249     res.tv_nsec = (guint32)t1;
 250   }
 251   return res;
 252 }
 253
 254 #endif // LTT_TIME_H