src/video_output/chrono.h

   1 /*****************************************************************************
   2  * chrono.h: vout chrono
   3  *****************************************************************************
   4  * Copyright (C) 2009-2010 Laurent Aimar
   5  * $Id$
   6  *
   7  * Authors: Laurent Aimar <fenrir _AT_ videolan _DOT_ org>
   8  *
   9  * This program is free software; you can redistribute it and/or modify it
  10  * under the terms of the GNU Lesser General Public License as published by
  11  * the Free Software Foundation; either version 2.1 of the License, or
  12  * (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  17  * GNU Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public License
  20  * along with this program; if not, write to the Free Software Foundation,
  21  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  22  *****************************************************************************/
  23
  24 #ifndef LIBVLC_VOUT_CHRONO_H
  25 #define LIBVLC_VOUT_CHRONO_H
  26
  27 #include <assert.h>
  28
  29 typedef struct {
  30     int     shift;
  31     vlc_tick_t avg;
  32     vlc_tick_t avg_initial;
  33
  34     int     shift_var;
  35     vlc_tick_t var;
  36
  37     vlc_tick_t start;
  38 } vout_chrono_t;
  39
  40 static inline void vout_chrono_Init(vout_chrono_t *chrono, int shift, vlc_tick_t avg_initial)
  41 {
  42     chrono->shift       = shift;
  43     chrono->avg_initial =
  44     chrono->avg         = avg_initial;
  45
  46     chrono->shift_var   = shift+1;
  47     chrono->var         = avg_initial / 2;
  48
  49     chrono->start = VLC_TICK_INVALID;
  50 }
  51 static inline void vout_chrono_Clean(vout_chrono_t *chrono)
  52 {
  53     VLC_UNUSED(chrono);
  54 }
  55 static inline void vout_chrono_Start(vout_chrono_t *chrono)
  56 {
  57     chrono->start = vlc_tick_now();
  58 }
  59 static inline vlc_tick_t vout_chrono_GetHigh(vout_chrono_t *chrono)
  60 {
  61     return chrono->avg + 2 * chrono->var;
  62 }
  63 static inline vlc_tick_t vout_chrono_GetLow(vout_chrono_t *chrono)
  64 {
  65     return __MAX(chrono->avg - 2 * chrono->var, 0);
  66 }
  67
  68 static inline void vout_chrono_Stop(vout_chrono_t *chrono)
  69 {
  70     assert(chrono->start != VLC_TICK_INVALID);
  71
  72     /* */
  73     const vlc_tick_t duration = vlc_tick_now() - chrono->start;
  74     const vlc_tick_t var = llabs( duration - chrono->avg );
  75
  76     /* Update average only if the current point is 'valid' */
  77     if( duration < vout_chrono_GetHigh( chrono ) )
  78         chrono->avg = (((1 << chrono->shift) - 1) * chrono->avg + duration) >> chrono->shift;
  79     /* Always update the variance */
  80     chrono->var = (((1 << chrono->shift_var) - 1) * chrono->var + var) >> chrono->shift_var;
  81
  82     /* For assert */
  83     chrono->start = VLC_TICK_INVALID;
  84 }
  85 static inline void vout_chrono_Reset(vout_chrono_t *chrono)
  86 {
  87     vout_chrono_t ch = *chrono;
  88     vout_chrono_Clean(chrono);
  89     vout_chrono_Init(chrono, ch.shift, ch.avg_initial);
  90 }
  91
  92 #endif