src/lib/time.c

   1 /************************************************************************
   2 * time.c
   3 * voxelands - 3d voxel world sandbox game
   4 * Copyright (C) Lisa 'darkrose' Milne 2016 <lisa@ltmnet.com>
   5 *
   6 * This program is free software: you can redistribute it and/or modify
   7 * it under the terms of the GNU General Public License as published by
   8 * the Free Software Foundation, either version 3 of the License, or
   9 * (at your option) any later version.
  10 *
  11 * This program is distributed in the hope that it will be useful, but
  12 * WITHOUT ANY WARRANTY; without even the implied warranty of
  13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  14 * See the GNU General Public License for more details.
  15 *
  16 * You should have received a copy of the GNU General Public License
  17 * along with this program.  If not, see <http://www.gnu.org/licenses/>
  18 ************************************************************************/
  19
  20 #include "common.h"
  21
  22 #include <time.h>
  23
  24 #ifndef WIN32
  25 #include <unistd.h>
  26 #include <errno.h>
  27 #include <sys/time.h>
  28 #else
  29 #include <windows.h>
  30 #endif
  31
  32 #ifndef WIN32
  33 static struct timeval start;
  34 #else
  35 static DWORD start;
  36 #define TIME_WRAP_VALUE (~(DWORD)0)
  37 #endif
  38
  39 /* initialise time */
  40 void time_init()
  41 {
  42 #ifndef WIN32
  43         gettimeofday(&start, NULL);
  44 #else
  45         timeBeginPeriod(1);
  46         start = timeGetTime();
  47 #endif
  48 }
  49
  50 /* get number of milliseconds since start */
  51 uint32_t time_ticks(void)
  52 {
  53 #ifndef WIN32
  54         uint32_t ticks;
  55         struct timeval now;
  56         gettimeofday(&now, NULL);
  57         ticks = (now.tv_sec-start.tv_sec)*1000+(now.tv_usec-start.tv_usec)/1000;
  58         return ticks;
  59 #else
  60         DWORD now = timeGetTime();
  61         DWORD ticks;
  62         if (now < start) {
  63                 ticks = (TIME_WRAP_VALUE-start) + now;
  64         }else{
  65                 ticks = (now - start);
  66         }
  67
  68         return ticks;
  69 #endif
  70 }
  71
  72 /* high resolution sleep() */
  73 void delay(uint32_t ms)
  74 {
  75 #ifndef WIN32
  76         struct timespec elapsed;
  77         struct timespec tv;
  78         int was_error;
  79
  80         /* Set the timeout interval */
  81         elapsed.tv_sec = ms/1000;
  82         elapsed.tv_nsec = (ms%1000)*1000000;
  83         do {
  84                 errno = 0;
  85
  86                 tv.tv_sec = elapsed.tv_sec;
  87                 tv.tv_nsec = elapsed.tv_nsec;
  88                 was_error = nanosleep(&tv, &elapsed);
  89         } while (was_error && (errno == EINTR));
  90 #else
  91         Sleep(ms);
  92 #endif
  93 }
  94
  95 /*
  96  * for animation timing
  97  * returns the seconds since last
  98  */
  99 float time_dtime(uint32_t last)
 100 {
 101         uint32_t now = time_ticks();
 102         uint32_t elapsed = now-last;
 103         return (float)elapsed/1000.0;
 104 }
 105
 106 /* essentially a frame capper */
 107 uint32_t interval_delay(uint32_t last, uint32_t hz)
 108 {
 109         if (last) {
 110                 uint32_t now = time_ticks();
 111                 uint32_t elapsed = now-last;
 112                 uint32_t timer = 1000/hz;
 113                 uint32_t idelay;
 114                 /*
 115                  * If elapsed is greater than timer, this could really mess up
 116                  * the frame rate due to a negative value rolling over to an
 117                  * insanely high positive value, so only delay if we have to.
 118                  */
 119                 if (timer > elapsed) {
 120                         idelay = timer-elapsed;
 121                         delay(idelay);
 122                 }
 123         }
 124         return time_ticks();
 125 }
 126
 127 /* get the frames per second */
 128 uint32_t calc_fps(uint32_t prev, uint32_t current)
 129 {
 130         uint32_t diff = (current-prev);
 131         if (diff) {
 132                 return 1000/diff;
 133         }else{
 134                 return 1000;
 135         }
 136 }