src/video/avi/timer.cpp

   1 #include "video/avi/timer.hpp"
   2 #include "library/minmax.hpp"
   3
   4 timer::timer(uint32_t rate_n, uint32_t rate_d)
   5 {
   6         w = n = 0;
   7         set_step(rate_n, rate_d);
   8 }
   9
  10 void timer::rate(uint32_t rate_n, uint32_t rate_d)
  11 {
  12         double old_d = d;
  13         uint64_t old_d2 = d;
  14         set_step(rate_n, rate_d);
  15         //Adjust n.
  16         if(d == old_d2)
  17                 return;
  18         n = n * (d / old_d) + 0.5;
  19         w += (n / d);
  20         n %= d;
  21 }
  22
  23 // The highest value rate_n can safely have: 9,223,372,036,854,775,808
  24 // The highest value rate_d can safely have: 18,446,744,073
  25 void timer::set_step(uint32_t rate_n, uint32_t rate_d)
  26 {
  27         uint64_t maxnscl = 9223372036854775808ULL / rate_n;
  28         uint64_t maxdscl = 18446744073ULL / rate_d;
  29         uint64_t maxscl = min(maxnscl, maxdscl);
  30         uint64_t _rate_n = maxscl * rate_n;
  31         uint64_t _rate_d = maxscl * rate_d;
  32         d = _rate_n;
  33         sw = 1000000000ULL * _rate_d / _rate_n;
  34         sn = 1000000000ULL * _rate_d % _rate_n;
  35 }
  36
  37 uint64_t timer::read_next()
  38 {
  39         uint64_t tmp_w = w + sw;
  40         uint64_t tmp_n = n + sn;
  41         tmp_w += (tmp_n / d);
  42         tmp_n %= d;
  43         return tmp_w;
  44 }
  45
  46 void timer::reset()
  47 {
  48         w = n = 0;
  49 }